Arctic Sea Ice : Forum

Cryosphere => Arctic sea ice => Topic started by: Neven on January 10, 2015, 12:21:28 AM

Title: 2015 sea ice area and extent data
Post by: Neven on January 10, 2015, 12:21:28 AM
This thread replaces the 2014 version (http://forum.arctic-sea-ice.net/index.php/topic,743.0.html).

Both CT SIA and IJIS SIE are going relatively low at the moment:

(https://lh6.googleusercontent.com/-gEPDVMMbd_g/VLBgI5cLfUI/AAAAAAAACA0/2GXnlTpVD8w/w868-h550-no/CTSIA20150107.png)

(https://lh5.googleusercontent.com/-cBr4LKrpiFU/VLBiMvj2TRI/AAAAAAAACCE/0UWr32dEl4w/s938/IJISSIE20150108.png)

Last post from the previous thread by Jim Pettit:

Quote

CT Area:
11,727,834 km2 (08 January [Day 0.0192])
9,493,824 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Up 30,917 km2 from previous day.
Up 236,345 km2 over past seven days (daily average: 33,764 km2).
Up 265,118 km2 for the month of January (daily average: 33,140 km2).
355,392 km2 below 2000s average for this date.
57,213 km2 below 2010s average for this date.
138,311 km2 below 2014 value for this date.
461,320 km2 below 2012 value for this date.
4th lowest January to-date average.
3rd lowest value for the date.
0 days this year (0% year-to-date) have recorded the lowest daily area.
0 days (0%) have recorded the second lowest.
2 days (25%) have recorded the third lowest.
2 days in total (25%) have been among the lowest three on record.

IJIS Extent:
12,582,981 km2 (08 January)
9,405,526 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Down 9,953 km2 from previous day.
Up 68,212 km2 over past seven days (daily average: 9,745 km2).
Up 101,619 km2 for the month of January (daily average: 12,702 km2).
634,021 km2 below 2000s average for this date.
140,998 km2 below 2010s average for this date.
10,214 km2 below 2014 value for this date.
437,247 km2 below 2012 value for this date.
4th lowest January to-date average.
2nd lowest value for the date.
0 days this year (0% year-to-date) have recorded the lowest daily extent.
2 days (25%) have recorded the second lowest.
3 days (37.5%) have recorded the third lowest.
5 days (62.5%) in total have been among the three lowest on record.

Have at it.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on January 10, 2015, 09:08:39 AM
In addition to the total Arctic figures I keep calculating daily sea ice area and extent for the regions. Source of the calculations are gridded sea ice concentration data as calculated by several institutions.

For NSIDC data my results can be found here:
https://sites.google.com/site/arctischepinguin/home/sea-ice-extent-area/data (https://sites.google.com/site/arctischepinguin/home/sea-ice-extent-area/data)

(data here should follow official NSIDC and Crysosphere Today figures closely)

For Jaxa-AMSR2:
https://sites.google.com/site/arctischepinguin/home/amsr2/data/Jaxa_AMSR2_L3_10km_Area_Extent-v0.0.txt (https://sites.google.com/site/arctischepinguin/home/amsr2/data/Jaxa_AMSR2_L3_10km_Area_Extent-v0.0.txt)

(data here are close but not an exact match for the Jaxa/IJIS numbers)

For Uni Hamburg AMSR2 ASI/3.125km data:
https://sites.google.com/site/arctischepinguin/home/amsr2/data/UH_AMSR2_3.125km_Area_Extent-v0.0.txt (https://sites.google.com/site/arctischepinguin/home/amsr2/data/UH_AMSR2_3.125km_Area_Extent-v0.0.txt)

(more datails can be found in the Home Brew thread (https://forum.arctic-sea-ice.net/index.php/topic,382.0.html))

Here are daily updated regional graphs based on the NSIDC sea ice concentration product:

(https://sites.google.com/site/arctischepinguin/home/sea-ice-extent-area/grf/nsidc-nt-regional-extent-overview.png)
LINK (https://sites.google.com/site/arctischepinguin/home/sea-ice-extent-area/grf/nsidc-nt-regional-extent-overview.png)

(https://sites.google.com/site/arctischepinguin/home/sea-ice-extent-area/grf/nsidc-nt-regional-area-overview.png)
LINK (https://sites.google.com/site/arctischepinguin/home/sea-ice-extent-area/grf/nsidc-nt-regional-area-overview.png)
Title: Re: 2015 sea ice area and extent data
Post by: Lord M Vader on January 10, 2015, 10:46:52 AM
Neven: just a note, the extent value of 12,582,981 km2 is incorrect. The value refers to the date for January 2014! The correct value is 12 572 767 km2.

//LMV
Title: Re: 2015 sea ice area and extent data
Post by: Jim Hunt on January 10, 2015, 12:06:12 PM
And the IJIS number for January 9th 2015 is the lowest on record for the date - 12,585,887 km2
Title: Re: 2015 sea ice area and extent data
Post by: Lord M Vader on January 10, 2015, 02:05:24 PM
Well, Jim Hunt, I'm not surprised given that the Pacific waters have been anomalously warm for a long time now. The North Atlantic waters are chewing up the sea ice in Barents Sea. Meaning that it will take more time for sea ice to form. This trend will continue with no light in the future..

It should be interesting to see whether we will have an all time low maximum in March..
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on January 10, 2015, 03:10:25 PM
IJIS extent is in first place for the first time since the second week of March, 2014:

IJIS Extent:
12,585,887 km2 (09 January) [corrected]
9,459,899 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Up 13,120 km2 from previous day.
Up 116,847 km2 over past seven days (daily average: 16,692 km2).
Up 114,739 km2 for the month of January (daily average: 12,749 km2).
668,148 km2 below 2000s average for this date.
174,240 km2 below 2010s average for this date.
51,467 km2 below 2014 value for this date.
534,542 km2 below 2012 value for this date.
4th lowest January to-date average.
Lowest value for the date.
1 day this year (11.11% year-to-date) has recorded the lowest daily extent.
2 days (22.22%) have recorded the second lowest.
3 days (33.33%) have recorded the third lowest.
6 days (66.67%) in total have been among the three lowest on record.
Title: Re: 2015 sea ice area and extent data
Post by: crandles on January 10, 2015, 03:42:23 PM
Neven: just a note, the extent value of 12,582,981 km2 is incorrect. The value refers to the date for January 2014! The correct value is 12 572 767 km2.

//LMV

Maybe this should have been addressed to Jim Pettit whose automated procedure still picks up 2014 data

9 Jan 2014 12637354
9 Jan 2015 12585887
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on January 10, 2015, 03:55:20 PM
Neven: just a note, the extent value of 12,582,981 km2 is incorrect. The value refers to the date for January 2014! The correct value is 12 572 767 km2.

//LMV

Maybe this should have been addressed to Jim Pettit whose automated procedure still picks up 2014 data

9 Jan 2014 12637354
9 Jan 2015 12585887

There was a single reference in my algorithms still pointing to the 2014 data, which has been fixed. However, I should note that all the other calculations in my updates--daily, weekly, and monthly changes, along with ranks, etc.--were and still are being performed properly, and based on the correct reference.

Ah, January. I do love you so... :\
Title: Re: 2015 sea ice area and extent data
Post by: crandles on January 10, 2015, 03:56:57 PM
Very good, thank you Jim.  :)
Title: Re: 2015 sea ice area and extent data
Post by: Lord M Vader on January 10, 2015, 04:09:11 PM
January is a really good month, right!! :)
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on January 11, 2015, 02:39:52 PM

CT Area:
11,717,905 km2 (10 January [Day 0.0247])
9,483,896 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Up 46,864 km2 from previous day.
Up 177,199 km2 over past seven days (daily average: 25,314 km2).
Up 255,189 km2 for the month of January (daily average: 25,519 km2).
465,750 km2 below 2000s average for this date.
101,533 km2 below 2010s average for this date.
30,814 km2 below 2014 value for this date.
613,404 km2 below 2012 value for this date.
4th lowest January to-date average.
3rd lowest value for the date.
0 days this year (0% year-to-date) have recorded the lowest daily area.
0 days (0%) have recorded the second lowest.
4 days (40%) have recorded the third lowest.
4 days in total (40%) have been among the lowest three on record.

IJIS Extent:
12,614,229 km2 (10 January)
9,436,774 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Up 28,342 km2 from previous day.
Up 122,256 km2 over past seven days (daily average: 17,465 km2).
Up 143,081 km2 for the month of January (daily average: 14,308 km2).
674,887 km2 below 2000s average for this date.
204,854 km2 below 2010s average for this date.
132,676 km2 below 2014 value for this date.
563,542 km2 below 2012 value for this date.
3rd lowest January to-date average.
2nd lowest value for the date.
1 days this year (10% year-to-date) has recorded the lowest daily extent.
3 days (30%) have recorded the second lowest.
3 days (30%) have recorded the third lowest.
7 days (70%) in total have been among the three lowest on record.

Title: Re: 2015 sea ice area and extent data
Post by: BornFromTheVoid on January 11, 2015, 05:03:51 PM
Update for the week to January 10th

The current 5 day mean is on 13,171,300km2 while the 1 day extent is at 13,231,900km2.

The daily anomaly (compared to 81-10) is at -923,350km2, an increase from -710,630km2 last week. The anomaly compared to the 07, 11 and 12 average is at -159,920km2, an increase from -6,010km2 last week. We're currently 2nd lowest on record, compared to 4th last week.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FtwVnHj0.jpg&hash=def82143d4b820296f7d0d03b26b7a29)

The average daily change over the last 7 days was +19.1k/day, compared to the long term average of +49.5k/day, and the 07, 11 and 12 average of +41.1k/day.

The average long term change over the next week is +38.2k/day, with the 07, 11, and 12 average being +27.8k/day.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FSsrkGYL.jpg&hash=9f201a0c37fac8bf5cdec77569687bff)

The increase so far this January is the smallest on record. To achieve the largest recorded monthly increase, a daily gain of over 74.1k/day is required, while the smallest requires a gain of less than 27.7k/day and an average requires +42.6k/day.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FTSLEHiC.jpg&hash=129f4ba3fc97ed031131dd2556f81ae3)
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on January 13, 2015, 02:18:58 PM

CT Area:
11,738,707 km2 (12 January [Day 0.0302])
9,504,697 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Up 28,053 km2 from previous day.
Up 80,944 km2 over past seven days (daily average: 11,563 km2).
Up 275,991 km2 for the month of January (daily average: 22,999 km2).
482,712 km2 below 2000s average for this date.
120,867 km2 below 2010s average for this date.
121,422 km2 below 2014 value for this date.
581,909 km2 below 2012 value for this date.
3rd lowest January to-date average.
3rd lowest value for the date.
0 days this year (0% year-to-date) have recorded the lowest daily area.
1 day (8.33%) has recorded the second lowest.
5 days (41.67%) have recorded the third lowest.
6 days in total (50%) have been among the lowest three on record.

IJIS Extent:
12,797,534 km2 (12 January)
9,620,079 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Up 105,824 km2 from previous day.
Up 213,606 km2 over past seven days (daily average: 30,515 km2).
Up 326,386 km2 for the month of January (daily average: 27,199 km2).
560,042 km2 below 2000s average for this date.
163,896 km2 below 2010s average for this date.
99,748 km2 below 2014 value for this date.
518,942 km2 below 2012 value for this date.
2nd lowest January to-date average.
3rd lowest value for the date.
1 days this year (8.33% year-to-date) has recorded the lowest daily extent.
4 days (33.33%) have recorded the second lowest.
4 days (33.33%) have recorded the third lowest.
9 days (75%) in total have been among the three lowest on record.
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on January 19, 2015, 01:01:35 PM
IJIS Extent:
13,210,842 km2 (18 January)
10,033,387 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Up 51,857 km2 from previous day.
Up 519,132 km2 over past seven days (daily average: 74,162 km2).
Up 739,694 km2 for the month of January (daily average: 41,094 km2).
415,841 km2 below 2000s average for this date.
42,370 km2 above 2010s average for this date.
50,961 km2 above 2014 value for this date.
115,299 km2 above 2012 value for this date.
2nd lowest January to-date average.
5th lowest value for the date.
1 day this year (5.56% year-to-date) has recorded the lowest daily extent.
4 days (22.22%) have recorded the second lowest.
5 days (27.78%) have recorded the third lowest.
10 days (55.56%) in total have been among the three lowest on record.
Title: Re: 2015 sea ice area and extent data
Post by: BornFromTheVoid on January 19, 2015, 02:03:25 PM
Update for the week to January 17th

The current 5 day mean is on 13,594,000km2 while the 1 day extent is at 13,713,800km2.

The daily anomaly (compared to 81-10) is at -767,750km2, a decrease from -923,350km2 last week. The anomaly compared to the 07, 11 and 12 average is at +68,160km2, a decrease from -159,920km2 last week. We're currently 5th lowest on record, compared to 2nd last week.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FkorCiEv.jpg&hash=0c770c773a704d443f603d19cd34e852)


The average daily change over the last 7 days was +60.4k/day, compared to the long term average of +38.2k/day, and the 07, 11 and 12 average of +27.8k/day.

The average long term change over the next week is +38.9k/day, with the 07, 11, and 12 average being +39.4k/day.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2Ft655PZl.jpg&hash=cda79b1824110423731e046ddd165d1f)


The increase so far this January is the 8th smallest on record. To achieve the largest recorded monthly increase, a daily gain of over 80.9k/day is required, while the smallest requires a gain of less than 11.3k/day and an average requires +39.8k/day.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FoKG5OEv.jpg&hash=26f632fe8f6aefc92c77edd27969b95c)
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on January 24, 2015, 02:27:31 PM

CT Area:
12,486,433 km2 (23 January [Day 0.0603])
10,252,424 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Up 32,208 km2 from previous day.
Up 305,633 km2 over past seven days (daily average: 43,662 km2).
Up 1,023,717 km2 for the month of January (daily average: 44,509 km2).
248,969 km2 below 2000s average for this date.
213,815 km2 above 2010s average for this date.
99,296 km2 above 2014 value for this date.
202,494 km2 above 2012 value for this date.
5th lowest January to-date average.
9th lowest value for the date.
0 days this year (0% year-to-date) have recorded the lowest daily area.
1 day (4.35%) has recorded the second lowest.
5 days (21.74%) have recorded the third lowest.
6 days in total (26.09%) have been among the lowest three on record.

IJIS Extent:
13,387,581 km2 (23 January)
10,210,126 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Up 58,324 km2 from previous day.
Up 248,162 km2 over past seven days (daily average: 35,452 km2).
Up 916,433 km2 for the month of January (daily average: 39,845 km2).
409,098 km2 below 2000s average for this date.
42,120 km2 above 2010s average for this date.
32,657 km2 below 2014 value for this date.
16,227 km2 below 2012 value for this date.
3rd lowest January to-date average.
5th lowest value for the date.
1 days this year (4.35% year-to-date) has recorded the lowest daily extent.
4 days (17.39%) have recorded the second lowest.
5 days (21.74%) have recorded the third lowest.
10 days (43.48%) in total have been among the three lowest on record.
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on January 28, 2015, 12:58:36 PM

CT Area:
12,700,735 km2 (27 January [Day 0.0713])
10,466,726 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Up 74,357 km2 from previous day.
Up 266,775 km2 over past seven days (daily average: 38,111 km2).
Up 1,238,019 km2 for the month of January (daily average: 45,853 km2).
122,505 km2 below 2000s average for this date.
303,928 km2 above 2010s average for this date.
182,716 km2 above 2014 value for this date.
304,209 km2 above 2012 value for this date.
Sixth lowest January to-date average.
9th lowest value for the date.
0 days this year (0% year-to-date) have recorded the lowest daily area.
1 day (3.7%) has recorded the second lowest.
5 days (18.52%) have recorded the third lowest.
6 days in total (22.22%) have been among the lowest three on record.

IJIS Extent:
13,329,480 km2 (27 January)
10,152,025 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Down 1,341 km2 from previous day.
Up 106,457 km2 over past seven days (daily average: 15,208 km2).
Up 858,332 km2 for the month of January (daily average: 31,790 km2).
609,960 km2 below 2000s average for this date.
138,294 km2 below 2010s average for this date.
213,019 km2 below 2014 value for this date.
125,579 km2 below 2012 value for this date.
3rd lowest January to-date average.
2nd lowest value for the date.
1 day this year (3.7% year-to-date) have recorded the lowest daily extent.
5 days (18.52%) has recorded the second lowest.
7 days (25.93%) have recorded the third lowest.
13 days (48.15%) in total have been among the three lowest on record.
Title: Re: 2015 sea ice area and extent data
Post by: BornFromTheVoid on February 01, 2015, 05:32:58 PM
Apologies for the delay. A broken finger and a lack of time means this will be a double update, for last weekend and this.

Update for the week to January 24th


The current 5 day mean is on 13,812,600km2 while the 1 day extent is at 13,890,700km2.

The daily anomaly (compared to 81-10) is at -821,270km2, an increase from -767,750km2 last week. The anomaly compared to the 07, 11 and 12 average is at +10,650km2, a decrease from +68,160km2 last week. We're currently 5th lowest on record, the same as last week.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FeQEQobc.png&hash=7aa27a1b79a3269b7b129c2a0e09c327)


The average daily change over the last 7 days was +31.2k/day, compared to the long term average of +38.9k/day, and the 07, 11 and 12 average of +39.4k/day.

The average long term change over the next week is +34.0k/day, with the 07, 11, and 12 average being +32.9k/day.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FMGU56Nd.png&hash=9c2bcf17a7ecbe4c831a24b926ae20a8)

The increase so far this January is the 9th smallest on record. To achieve the largest recorded monthly increase, a daily gain of over 130.6k/day is required, while the smallest requires a loss of at least 8.6k/day and an average requires an increase of +60.8k/day.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2F7NOnhX5.png&hash=6f6a2d3bd8d12c449de2e4fa2bbcbfa6)
Title: Re: 2015 sea ice area and extent data
Post by: BornFromTheVoid on February 01, 2015, 06:19:13 PM
Update for the week to January 31st


The current 5 day mean is on 13,991,700km2 while the 1 day extent is at 14,124,860km2.


The daily anomaly (compared to 81-10) is at -880,120km2, an increase from -821,270km2 last week. The anomaly compared to the 07, 11 and 12 average is at -40,490km2, a decrease from +10,650km2 last week. We're currently 4th lowest on record, down from 5th last week.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FB4BtN0S.png&hash=b34896128de0719972cbd4f644149bc5)


The average daily change over the last 7 days was +25.6k/day, compared to the long term average of +34.0k/day, and the 07, 11 and 12 average of +32.9k/day.

The average long term change over the next week is +28.0k/day, with the 07, 11, and 12 average being +18.3k/day.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FCeaNXGA.png&hash=1a19e9aedb2d48e122a0017dc48e0950)


The increase in January was the 10th smallest on record.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FqmnHDcu.png&hash=ca260c9c2ad686d794b6f69601b7c786)

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2F9aL2CF0.png&hash=8fc7fa18f12829269536565c2bdece2d)
Title: Re: 2015 sea ice area and extent data
Post by: BornFromTheVoid on February 08, 2015, 05:25:53 PM
Update for the week to February 7th

The current 5 day mean is on 14,226,500km2 while the 1 day extent is at 14,222,990km2.

The daily anomaly (compared to 81-10) is at -841,310km2, a decrease from -880,120km2 last week. The anomaly compared to the 07, 11 and 12 average is at +66,220km2, an increase from -40,490km2 last week. We're currently 6th lowest on record, up from 4th last week.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FJWr8Z1z.png&hash=134d5b7e3be8e0733cac39c04e7a9847)

The average daily change over the last 7 days was +33.5k/day, compared to the long term average of +28.0k/day, and the 07, 11 and 12 average of +18.3k/day.
The average long term change over the next week is +18.9k/day, with the 07, 11, and 12 average being +32.8k/day.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2Fcb3XGS5.png&hash=339ca1985451a37501c2e699db86ca3b)

The increase so far this February is the 12th largest on record. To achieve the largest recorded monthly increase, a daily gain of over 30.2k/day is required, while the smallest requires a loss of at least 6.1k/day and an average requires an increase of +15.6k/day.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2F1XCMsf2.png&hash=e966b3d91f8fc63d687856fabc2d894c)
Title: Re: 2015 sea ice area and extent data
Post by: BornFromTheVoid on February 16, 2015, 11:53:05 AM
Update for the week to February 14th

The current 5 day mean is on 14,392,900km2 while the 1 day extent is at 14,426,260km2.

The daily anomaly (compared to 81-10) is at -807,680km2, a decrease from -841,310km2 last week. The anomaly compared to the 07, 11 and 12 average is at +3,280km2, an decrease from +66,220km2 last week. We're currently 5th lowest on record, up from 6th last week.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FxapPDEK.png&hash=bdd42f2b471f9533a96ca1f31f8c7fa8)

The average daily change over the last 7 days was +23.8k/day, compared to the long term average of +18.9k/day, and the 07, 11 and 12 average of +32.8k/day.
The average long term change over the next week is +20.9k/day, with the 07, 11, and 12 average being +22.8k/day.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FyhyVGzB.png&hash=e6c891dee9a522b44321f3810c733b1c)

The increase so far this February is the 14th largest on record. To achieve the largest recorded monthly increase, a daily gain of over 33.1k/day is required, while the smallest requires a loss of at least 20.1k/day and an average requires an increase of +11.7k/day.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FsJe8qYD.png&hash=db0af8534698c94fa5069f533dfb5ba1)
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on February 17, 2015, 02:58:55 PM
IJIS Extent:
13,883,835 km2 (16 February)
10,706,380 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Down 58,225 km2 from previous day.
Up 100,003 km2 over past seven days (daily average: 14,286 km2).
Up 337,383 km2 for the month of February (daily average: 21,086 km2).
558,544 km2 below 2000s average for this date.
127,469 km2 below 2010s average for this date.
88,528 km2 above 2014 value for this date.
178,655 km2 below 2012 value for this date.
Sixth lowest February to-date average.
Third lowest value for the date.
1 day this year (2.13% year-to-date) has recorded the lowest daily extent.
7 days (14.89%) have recorded the second lowest.
13 days (27.66%) have recorded the third lowest.
21 days (44.68%) in total have been among the three lowest on record.


CT Area:
13,233,112 km2 (16 February [Day 0.126])
10,999,103 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Up 82,176 km2 from previous day.
Up 490,897 km2 over past seven days (daily average: 70,128 km2).
Up 520,046 km2 for the month of February (daily average: 32,503 km2).
196,879 km2 below 2000s average for this date.
194,175 km2 above 2010s average for this date.
459,896 km2 above 2014 value for this date.
320,777 km2 above 2012 value for this date.
8th lowest February to-date average.
8th lowest value for the date.
0 days this year (0% year-to-date) have recorded the lowest daily area.
1 day (2.13%) has recorded the second lowest.
5 days (10.64%) have recorded the third lowest.
6 days in total (12.77%) have been among the lowest three on record.
Title: Re: 2015 sea ice area and extent data
Post by: viddaloo on February 17, 2015, 08:26:38 PM
Up 337,383 km2 for the month of February (daily average: 21,086 km2).
This makes us 4th lowest so far in February.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fd22d7v2y1t140g.cloudfront.net%2Fm_13618418_PubkYZec7p6b.png&hash=f723e889c6ae33d47a3b2e0e8909c7f3)
Title: Re: 2015 sea ice area and extent data
Post by: Jim Hunt on February 18, 2015, 05:26:11 PM
Since Jim P doesn't seem to have popped in yet, it seems both IJIS and NSIDC show February 17th as their lowest ever values for the date in the respective recorded histories:

http://GreatWhiteCon.info/2015/02/shock-news-ijis-arctic-sea-ice-extent-lowest-ever/#comment-196444 (http://GreatWhiteCon.info/2015/02/shock-news-ijis-arctic-sea-ice-extent-lowest-ever/#comment-196444)

Whether CT area follows suit we won't find out for another couple of days, but it has a long way to fall in order to do so.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on February 18, 2015, 05:52:07 PM
Whether CT area follows suit we won't find out for another couple of days, but it has a long way to fall in order to do so.

From area calculated from NSIDC sea ice concentration I expect the following changes of  CT-area:

Thu: -114k
Fri: -154k

Will that do?
Title: Re: 2015 sea ice area and extent data
Post by: Jim Hunt on February 18, 2015, 08:57:34 PM
Will that do?

Thanks Wipneus, but not quite (if my spreadsheet is to be believed). That would take us down to 12.965 versus an all time minimum of 12.835?

However if this continues for another day or two?
Title: Re: 2015 sea ice area and extent data
Post by: DavidR on February 18, 2015, 10:23:17 PM
Will that do?

Thanks Wipneus, but not quite (if my spreadsheet is to be believed). That would take us down to 12.965 versus an all time minimum of 12.835?

However if this continues for another day or two?
Based on Jim Pettits' last figures we are missing Wednesdays' figures from this calculation.  If the Wednesday CT drop was significant we might get a lot closer to that 12.835 figure.
These massive fluctuations have to be more to  do with wind than melt  though.   

As an afterthought, I  wonder what  effect having all this ice rushing about has on ice formation. I  suspect that the ice is not thickening or consolidating while it is being thrown about in the recent storms.
Title: Re: 2015 sea ice area and extent data
Post by: jdallen on February 19, 2015, 04:19:10 AM
Will that do?

Thanks Wipneus, but not quite (if my spreadsheet is to be believed). That would take us down to 12.965 versus an all time minimum of 12.835?

However if this continues for another day or two?
Based on Jim Pettits' last figures we are missing Wednesdays' figures from this calculation.  If the Wednesday CT drop was significant we might get a lot closer to that 12.835 figure.
These massive fluctuations have to be more to  do with wind than melt  though.   

As an afterthought, I  wonder what  effect having all this ice rushing about has on ice formation. I  suspect that the ice is not thickening or consolidating while it is being thrown about in the recent storms.

Wind can mean melt (or at least, no thickening), even in winter, via Ekman pumping drawing heat to the surface from deeper water.

It has seemed pretty clear to me that there is a lot of melt happening at the margins of the pack as it gets shoved into the Barents and the upwelling near Svalbard.  That water is 2-3C at minimum, and would make short work of very thick ice, unless that ice was supported by very low  SST's.

The perturbation from wind I think will become increasingly important in how well the ice survives.  More wind, more surf, less ice, with almost certainty.

While the new low doesn't strike me as significant in and of itself, I think the scale of the drop is very telling.  For the ice to be in such poor condition that we could see that large a multi-day *drop* is unsettling.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on February 19, 2015, 07:13:44 AM

Based on Jim Pettits' last figures we are missing Wednesdays' figures from this calculation. 

Yes I did not realize CT was late. It still has not updated. These are the figures:

Wed: +43k
Thu: -114k
Fri: -154k

Attached the actual CT figures compared to my calculations

Title: Re: 2015 sea ice area and extent data
Post by: Jim Hunt on February 19, 2015, 08:32:18 AM
IJIS extent for February 18th shows a slight increase at 13,774,725 km², but remains the lowest reading for the date.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on February 20, 2015, 07:19:41 AM
From area calculated from NSIDC sea ice concentration I expect the following changes of  CT-area:

Fri: -154k
Sat: -19k
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on February 20, 2015, 01:52:49 PM
IJIS Extent:
13,789,853 km2 (19 February)
10,612,398 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Up 15,128 km2 from previous day.
Down 99,460 km2 over past seven days (daily average: -14,209 km2).
Up 243,401 km2 for the month of February (daily average: 12,811 km2).
707,712 km2 below 2000s average for this date.
231,145 km2 below 2010s average for this date.
145,229 km2 below 2014 value for this date.
343,682 km2 below 2012 value for this date.
5th lowest February to-date average.
2nd lowest value for the date.
3 days this year (6% year-to-date) have recorded the lowest daily extent.
8 days (16%) have recorded the second lowest.
13 days (26%) have recorded the third lowest.
24 days (48%) in total have been among the three lowest on record.


CT Area:
13,011,439 km2 (19 February [Day 0.1343])
10,777,430 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Down 149,235 km2 from previous day. (NOTE: third largest one-day February SIA decrease on record; largest two-day February SIA decrease on record)
Up 122,015 km2 over past seven days (daily average: 17,431 km2).
Up 298,373 km2 for the month of February (daily average: 15,704 km2).
527,528 km2 below 2000s average for this date.
95,805 km2 below 2010s average for this date.
178,301 km2 above 2014 value for this date.
25,034 km2 above 2012 value for this date.
8th lowest February to-date average.
5th lowest value for the date.
0 days this year (0% year-to-date) have recorded the lowest daily area.
1 day (2%) has recorded the second lowest.
5 days (10%) have recorded the third lowest.
6 days in total (12%) have been among the lowest three on record.

Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on February 20, 2015, 06:33:07 PM
From area calculated from NSIDC sea ice concentration I expect the following changes of  CT-area:

Sat: -19k
Sun: +29k

That was all for the moment.
Title: Re: 2015 sea ice area and extent data
Post by: Neven on February 21, 2015, 06:04:29 PM
From area calculated from NSIDC sea ice concentration I expect the following changes of  CT-area:

Fri: -154k
Sat: -19k

That means CT SIA will probably go lowest as well.
Title: Re: 2015 sea ice area and extent data
Post by: Jim Hunt on February 21, 2015, 08:06:31 PM
That means CT SIA will probably go lowest as well.

Not according to my trusty spreadsheet? I get 13.02 versus a minimum of 12.86
Title: Re: 2015 sea ice area and extent data
Post by: crandles on February 21, 2015, 09:35:54 PM
We have dropped by 264k compared with 2 data days ago.

12 of 36 years show gains from last data day to max of less than 264k, so possibly a 1 in 3 chance we have passed the max.

OTOH recent years have shown late maximums and large late rises:
only 2 of last 10 years have shown rises of less than 264k, so maybe only 1 in 5 chance ... or if this trend is continuing even less chance than that.

or maybe such differences arise by chance. Difference is fairly small: projected max using 36 years = 13.41 versus 13.44 using last 10 years so just 30k difference. As the maximum further increase for 1988 is 835k a difference of 30k seems likely to arise by chance.


Projected maximum of 13.41 or 13.44 would make 2015 4th lowest maximum area on record.

2nd lowest to 6th lowest maximum area on record seems a likely range (only 2 of 36 years take us to higher than 6th lowest)
Title: Re: 2015 sea ice area and extent data
Post by: Neven on February 22, 2015, 11:49:14 AM
That means CT SIA will probably go lowest as well.

Not according to my trusty spreadsheet? I get 13.02 versus a minimum of 12.86

Indeed, I subtracted twice.
Title: Re: 2015 sea ice area and extent data
Post by: BornFromTheVoid on February 22, 2015, 04:27:52 PM
Update for the week to February 21st

The current 5 day mean is on 14,367,470km2 while the 1 day extent is at 14,483,980km2.

The daily anomaly (compared to 81-10) is at -979,110km2, an increase from -807,680km2 last week. The anomaly compared to the 07, 11 and 12 average is at -181,500km2, an decrease from +3,280km2 last week. We're currently 2nd lowest on record, down from 5th last week.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2F10XqNnz.png&hash=7c45b074ce007ac5db3730e5da19109a)

The average daily change over the last 7 days was -3.7k/day, compared to the long term average of +20.9k/day, and the 07, 11 and 12 average of +22.8k/day.
The average long term change over the next week is +14.1k/day, with the 07, 11, and 12 average being +12.6k/day.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FBCitdM4.png&hash=f550c2b73ffa5bb7452c2a0efa4eaa5f)

The increase so far this February is the 12th smallest on record. To achieve the largest recorded monthly increase, a daily gain of over +74.7k/day is required, while the smallest requires a loss of at least 39.4k/day and an average requires an increase of +28.8k/day.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2Fxv2fBkE.png&hash=d75830d2b818c32b5ae4cbff2a47f939)
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on February 22, 2015, 06:49:51 PM
We have dropped by 264k compared with 2 data days ago.

12 of 36 years show gains from last data day to max of less than 264k, so possibly a 1 in 3 chance we have passed the max.

OTOH recent years have shown late maximums and large late rises:
only 2 of last 10 years have shown rises of less than 264k, so maybe only 1 in 5 chance ... or if this trend is continuing even less chance than that.

or maybe such differences arise by chance. Difference is fairly small: projected max using 36 years = 13.41 versus 13.44 using last 10 years so just 30k difference. As the maximum further increase for 1988 is 835k a difference of 30k seems likely to arise by chance.


Projected maximum of 13.41 or 13.44 would make 2015 4th lowest maximum area on record.

2nd lowest to 6th lowest maximum area on record seems a likely range (only 2 of 36 years take us to higher than 6th lowest)
My own prediction: SIA is five to six weeks from maximum, which will end up somewhere between 13.3 and 13.6 million km2 (Keep in mind that 2012 saw nearly 700k km2 of ice form after this date). Having said that, however, I agree that there remains a not-insignificant chance that this year's maximum has indeed already been reached.
Title: Re: 2015 sea ice area and extent data
Post by: Gray-Wolf on February 22, 2015, 08:34:37 PM
Surely any gains from this point in are transient 'ice factory' type ice and of no consequence through the coming melt season?

What is important are the changes to the ice types that stand a chance of surviving the melt season and where those ice types are in the run up to melt?

We saw Fram fire back up into a more normal pattern of drainage from the basin in December so we lost much of the ice that survived the past two melt seasons from in front of Fram  , and to the NE of Svalbard also.

We also saw Nares decondition the ice in Lincoln allowing rotation more freely in the Beaufort (under correct forcings)

so it is not what is happening that is most important than what we have seen happen surely?

Title: Re: 2015 sea ice area and extent data
Post by: Jim Hunt on February 22, 2015, 09:28:54 PM
What is important are the changes to the ice types that stand a chance of surviving the melt season and where those ice types are in the run up to melt?

What do you make of the current ASCAT then?

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fmanati.star.nesdis.noaa.gov%2Fascat_images%2Fice_image%2Fmsfa-NHe-a-2015051.sir.gif&hash=a9c5caba95305c8dd0962feea352223b)

The Pole itself looks vulnerable this year?
Title: Re: 2015 sea ice area and extent data
Post by: viddaloo on February 22, 2015, 09:36:02 PM
What do you make of the current ASCAT then?

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fmanati.star.nesdis.noaa.gov%2Fascat_images%2Fice_image%2Fmsfa-NHe-a-2015051.sir.gif&hash=a9c5caba95305c8dd0962feea352223b)
The ASCAT looks like something from a car. I suggest all new cars be delivered with mandatory ASCATs on their wheels that show the polar region at the time of purchase. People can then compare their 'progress' as they move to a new car, with updated ASCATs.
Title: Re: 2015 sea ice area and extent data
Post by: Jim Hunt on February 23, 2015, 10:33:09 AM
The ASCAT looks like something from a car. I suggest all new cars be delivered with mandatory ASCATs on their wheels that show the polar region at the time of purchase.

Is that your (tongue in cheek?) way of saying you don't understand what you're looking at?
Title: Re: 2015 sea ice area and extent data
Post by: viddaloo on February 23, 2015, 11:40:18 AM
Not at all. I'm sorry if I mix sciences and blend in some social science now and then. Seeing that driving a car is still legal in most countries, having ASCATs on the wheels as a mandatory arrangement might make drivers think twice before using their cars. In other news driving cars and flying planes is destroying this planet. Same planet as in the 'hard' sciences, BTW.
Title: Re: 2015 sea ice area and extent data
Post by: Jim Hunt on February 23, 2015, 12:11:21 PM
ASCAT images look rather like turbine blades also?
Title: Re: 2015 sea ice area and extent data
Post by: crandles on February 24, 2015, 01:44:12 AM
To try and reduce noise in day of maximum, I tried using a 31 day centred average. Cryosphere today area numbers. Still leaves noisy data, but anyway: The day of maximum looks strangely early in the period 1986 to 1998 and then no trend this century.

(https://farm9.staticflickr.com/8671/16421779507_9a21bd0384_z.jpg) (https://flic.kr/p/r28UVr)31centeredaveragemaximumday (https://flic.kr/p/r28UVr) by crandles2011 (https://www.flickr.com/people/67566729@N07/), on Flickr

Just random noise or is there likely to be an underlying cause, and if so what?
Title: Re: 2015 sea ice area and extent data
Post by: OSweetMrMath on February 24, 2015, 07:39:58 AM
To try and reduce noise in day of maximum, I tried using a 31 day centred average. Cryosphere today area numbers. Still leaves noisy data, but anyway: The day of maximum looks strangely early in the period 1986 to 1998 and then no trend this century.

Just random noise or is there likely to be an underlying cause, and if so what?

What you are trying to do is find the maximum of a function in the presence of noise, when the function is essentially flat at the maximum. This is a hard problem. Still, I have some thoughts.

Since you didn't say otherwise, I assume you are using an unweighted average. This is still sensitive to the noise at the ends of the averaging window. You may get better results with a weighted average. Depending on what software you are using, you should check for kernel smoothers or binomial smoothers or Gaussian smoothers, or possibly other terms. You may be able to smooth the data better, but with a smaller effective averaging window.

These smoothers all assume the noise is uncorrelated, which is probably not the case. There are statistical tools which perform smoothing with autocorrelated noise, so if you want to go that far you could probably find an R package which will do all the work for you, for example.

Even then, the variance is likely to be large, making year to year comparisons difficult. If you're really motivated, you could do a bootstrap estimate of the variance, but it's probably a lot of effort with little point.

Looking at the graph as is, there's no visual evidence of a trend, but you could do a test for a change point in 1998. Again, depending on what software you are using, you may be able to directly do a statistical test of whether the mean maximum day for years up to 1998 is different than the mean maximum day after 1998.

On the other hand, if there has been a change in the maximum day, I would expect it to be a smooth trend rather than a jump at a change point. Even if the change point test is statistically significant, I'm not sure it would be physically meaningful.
Title: Re: 2015 sea ice area and extent data
Post by: viddaloo on February 24, 2015, 09:59:28 AM
My 2 lepta.

As is, the 2007 IJIS extent maximum was the earliest on record at Feb 24th. When filtered weekly the max date adjusts to Feb 23rd. The rest of the 2004–2014 field when filtered is spread out rather narrowly from Mar 4th to Mar 18th, and centered around Mar 9–10th. Could 2015 be an even earlier outlier than 2007 with a Feb 15th extent maximum? Too early to tell, of course. But if we were to max out like 2007 on Feb 23rd, we would need daily delta gains of on average 33467 km² for the next 5 days. (If we were to max out like #2, 2009, on Mar 4th, we would need daily delta gains of on average 11952 km² for the next 14 days.

Is there at all any advantage to turning early for achieving brilliant melt during melt season? Hard to tell. We have not enough data, and 2012 that went lowest turned late (March 7th or 18th filtered), but lost 11.532 M km² during melt season, while earlybird 2007 lost 'only' 10.144 M km². At this point I'd say there's no connection between starting early and melting much.

and

A good melt in the earliest 3rd of melt season, with bountiful early melt ponds, is of importance for the final melt amount. The amount of melt ponds, however, isn't directly measured by sea ice extent. I believe an early numerical max extent date is mainly a random feature, becoming a little less random using a weekly filter, but ultimately doesn't say much about whether or not there will be a good melt in the earliest 3rd of melt season, and therefore neither says much about final melt amount.

If you want to quantify this, March melt is generally lousy, with an average loss of 181 000 km². April has an average loss of 1 122 000 km², and the first 3rd of May a monthly equivalent of on average 1 529 000 km². Some of the best melt seasons have sported huge extent *increases* during March, like 2010 which put on almost half a million km². So March is generally undecided and indecisive for final melt (while a good melt in the earliest 3rd of melt season IS decisive).

PS: When talking about the earliest 3rd of the melt season, I'm in effect operating with three 70–day periods, the first of these going from Mar 1 to May 9.
Title: Re: 2015 sea ice area and extent data
Post by: crandles on February 24, 2015, 12:42:27 PM
Thanks for the replies.  :D

I agree a trend would seem more likely than a step change. Perhaps there could be a trend with 81, 84 and 85 being unusually high by chance. But if it doesn't look like a trend then correlation with something might be a better possibility than a step change?

I wondered if there might be a correlation with PDO or some other ocean oscillation. Doesn't look too promising even though PDO did change from warm phase to cool around 1998.

There could be relations with PDO for pacific side and other indices for the atlantic side. Also not impossible to imagine a changing relation with PDO depending on level of ice on the Pacific side.

I am just using google sheets and searching for smoothers terms mentioned didn't find anything. I am sure you are right that there are better ways of finding a smoothed max and I probably should be able to do better with more effort. That ought to be done before I get too carried away with looking for PDO and other correlations. Whether the effort is worth it or not does seem rather questionable.

Anyway thanks for the comments.
Title: Re: 2015 sea ice area and extent data
Post by: crandles on February 24, 2015, 04:13:42 PM
Tried what I guess would be a binomial smoothing 15 day weighted average. I suspect this is too short a period for what I want as there were several instances of double peaks often up to two weeks or more apart. Anyway the days are not as interesting looking to me:


If I can get interesting or not interesting depending on the processing then I suspect I have probably already done too much processing of the data.


Title: Re: 2015 sea ice area and extent data
Post by: DavidR on February 24, 2015, 09:26:40 PM
Thanks for the replies.  :D

I agree a trend would seem more likely than a step change. Perhaps there could be a trend with 81, 84 and 85 being unusually high by chance. But if it doesn't look like a trend then correlation with something might be a better possibility than a step change?

The earlier maximums at the start of the period don't surprise me as, from a trend perspective, it's sea temperature and insolation that will stop expansion. The greater ice extent at the start of the period require it to be further south and thus exposed to  insolation, and consequent  sea warming, earlier.
Title: Re: 2015 sea ice area and extent data
Post by: epiphyte on February 24, 2015, 10:00:22 PM

Just random noise or is there likely to be an underlying cause, and if so what?

Crandles, I sent you a PM - but I've got a hunch it's the moon. I looked at a couple of years and, and at first sight both the periodicity of the peaks and the timing of the nearest spring tide w.r.t the peaks for each year seem roughly right?

Title: Re: 2015 sea ice area and extent data
Post by: crandles on February 25, 2015, 01:11:08 AM
I doubt I have been very precise with this so don't take it as gospel, but what I got for dates of 15 day binomial weighted average peak days was as follows:

No days after new/full moon, Frequency
0   1
1   1
2   2
3   8
4   1
5   2
6   3
7   4
8   1
9   4
10   5
11   0
12   2
13   2
   
____36

If the frequencies of 4 and 5 were next to the 8 it would be more convincing.

3 to 10 days later have 28 of 36 of the occurrences, which seems a high proportion for 8/14ths of the time but I think I did a bit of cherry picking in choosing that 3 to 10 days later period. 20.5 would be average and by choosing which period you are bound to be able to get a few more, so I doubt there is statistical significance there.

Maybe the 8 is more significant but I think more accuracy might be required. If 2 or 3 actually belonged to 2 or 4 days later rather than 3 then the distribution would look pretty flat.

Thus I am doubting there is much if any significance, but that doesn't prove there is no effect.

Maybe someone has a suitable test of significance to hand rather than relying on my judgement?
Title: Re: 2015 sea ice area and extent data
Post by: Peter Ellis on February 25, 2015, 10:25:14 AM
Is there a correlation between the day of the maximum and the magnitude of the maximum?

You could argue it either way - a longer freezing season might imply a later maximum (because it's a cold year, so stuff goes on freezing for longer), or it could imply an earlier maximum (a high maximum means more ice at lower latitudes, so melt will start sooner once the sun comes up).

Would be interesting to know if either of those is supported by the data.

You'll need to detrend the data for both the date of the maximum and the magnitude of the maximum, otherwise you may get a spurious correlation if both are changing over time for unrelated reasons.
Title: Re: 2015 sea ice area and extent data
Post by: crandles on February 26, 2015, 01:37:09 PM
Used 31 day average for magnitude and day of peak. Detrended, I got correlation of -0.108

Put the calculation here if you are interested or want to do more (like test for significance?):

https://docs.google.com/spreadsheets/d/1nY_gMHOpITIIw0OMo_nqZxvR0KufUw1oZlL8YD5T7m4/edit?usp=sharing

FWIW

The day trendline increases from day 64.4 to 71.6

I think the negative correlation is what I would expect. If the magnitude of the maximum is low then the ice is at high latitude and you have to wait longer for the sun to get high enough at the edge of the pack.

The alternative given "a longer freezing season might imply a later maximum" perhaps isn't quite what you meant, maybe 'a strong freezing season' might imply ... ?

If that is what you meant, strength of freezing season is mainly well before the peak and why should weather continue to be unusual in that direction rather than reverting to the mean?
Title: Re: 2015 sea ice area and extent data
Post by: Peter Ellis on February 26, 2015, 02:36:24 PM
Yeah, I meant a stronger freezing season.  I agree with you that I'd personally expect the weak negative correlation, but thought it was sufficiently arguable that I should present both options.

If you want a slightly more mechanistic version of it, you could say "Cold/warm weather conditions near the ice margins in March are likely to both increase/decrease the overall maximum and also prolong/shorten the melting season. This means you expect longer freezing seasons to correlate positively with higher maxima."
Title: Re: 2015 sea ice area and extent data
Post by: crandles on February 26, 2015, 03:09:12 PM
Not sure I really like your

If you want a slightly more mechanistic version of it, you could say "Cold/warm weather conditions near the ice margins in March are likely to both increase/decrease the overall maximum and also prolong/shorten the melting season. This means you expect longer freezing seasons to correlate positively with higher maxima."

Cold weather certainly will mean a late maximum but IMHO that might have very little affect on the area at maximum. It may have a strong effect on (peak area - area on say 15 Feb) but that isn't all that important to the peak area. I don't know if there is some sophisticated analysis possible there - tease out the effect of cold weather causing a late peak, adjust for that and then show a strong negative correlation between detrended maximum and date of maximum as adjusted for weather?

Title: Re: 2015 sea ice area and extent data
Post by: Steven on February 26, 2015, 09:23:33 PM
Used 31 day average for magnitude and day of peak. Detrended, I got correlation of -0.108
...
I think the negative correlation is what I would expect.

The correlation seems to be very weak.  In fact, it turns out that the sign of the correlation coefficient depends on the fact that you used 31-day averages.

E.g., using 15-day (rather than 31-day) simple moving averages, the correlation between the day of the maximum and the magnitude of the maximum is weakly positive, +0.09, if both time series are detrended.

So depending on how the maximum is calculated, you can obtain a weak negative or a weak positive correlation.
Title: Re: 2015 sea ice area and extent data
Post by: jdallen on February 27, 2015, 12:27:32 AM
Used 31 day average for magnitude and day of peak. Detrended, I got correlation of -0.108
...
I think the negative correlation is what I would expect.

So depending on how the maximum is calculated, you can obtain a weak negative or a weak positive correlation.

Which by extension implies neither correlation, casual relationship, or underlying common cause; at least no simple one.
Title: Re: 2015 sea ice area and extent data
Post by: BornFromTheVoid on March 01, 2015, 05:47:32 PM
Update for the week to February 28th

The current 5 day mean is on 14,412,600km2 while the 1 day extent is at 14,354,900km2.
The daily anomaly (compared to 81-10) is at -1,023,690km2, an increase from -979,110km2 last week. The anomaly compared to the 07, 11 and 12 average is at -215,6500km2, an increase from -181,500km2 last week. We're currently 2nd lowest on record, the same as last week.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FecHlarj.png&hash=d15a13014e115714a3d46d13197a773b)

The average daily change over the last 7 days was +7.7k/day, compared to the long term average of +14.1k/day, and the 07, 11 and 12 average of +12.6k/day.
The average long term change over the next week is +0.4k/day, with the 07, 11, and 12 average being +20.6k/day.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FwLXMBFv.png&hash=57e25c924ecfd27cd662c3c73adf4a2f)


The increase this February was the 9th smallest on record.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FOPmYkMC.png&hash=a5a38bc372810f4410bc4b29d7bf9730)

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FATWmerf.png&hash=f80bd3edbc804471e8c357a28dcf0ae9)
Title: Re: 2015 sea ice area and extent data
Post by: DavidR on March 01, 2015, 09:51:18 PM
BFTV,
I  can't see any way you  can have the NSIDC extent increasing by a greater amount in 2015 than 2014. My  figures show a maximum increase in Feb of just  414 K in 2015 compared with 470 in 2014.  Measuring from 31 Jan to  28 Feb gives an even starker difference of 230 K vs 456 K. 

Are you using the 5 day  average? That  might explain it as 2015 rose very  rapidly in the last week of January.  OK That's it  417 K in 2014 vs 429 in 2015. 

2015 rose almost 200 K in the last 5 days of Jan compared to  virtually no rise in 2014. The reverse occurred at the end of the month with 2015 dropping 100K and 2014 rising 160.  Hence the variation.
Title: Re: 2015 sea ice area and extent data
Post by: BornFromTheVoid on March 01, 2015, 10:00:58 PM
Yup, I'm using the 5 day trailing average, David
Title: Re: 2015 sea ice area and extent data
Post by: DavidR on March 01, 2015, 10:40:38 PM
BFTV,
It would be great to  see the entire series for March from now to the maximum to  see how likely  we are to get back up to the record low maximum extent.  On my  figures the average rise from now won't get  us back to the current maximum for 2015.   
Title: Re: 2015 sea ice area and extent data
Post by: crandles on March 02, 2015, 12:53:48 PM
For Cryosphere Today area numbers

following path of previous 36 years:

17 fail to get higher than 13.274 reached 11 data days ago
5 rise further but stay below 13.317 so 22 years paths keep this year as 2nd lowest maximum on record
2 rise to between 13.317 and 13.358 to be 3rd lowest maximum on record
4 rise to between 13.358 and 13.460 to be 4th lowest maximum on record
0 rise to between 13.460 and 13.487 to be 5th lowest maximum on record
8 rise to between 13.487 and 13.700 to be 6th lowest maximum on record (current 6th is 13.708)

average increase of last 10 or 36 year puts us 4th lowest maximum on record

If just use last 10 years, 4 show no rise past 13.274 peak. So just under half of the paths whether you use 10 years or 36 years.
Title: Re: 2015 sea ice area and extent data
Post by: BornFromTheVoid on March 02, 2015, 02:09:25 PM
BFTV,
It would be great to  see the entire series for March from now to the maximum to  see how likely  we are to get back up to the record low maximum extent.  On my  figures the average rise from now won't get  us back to the current maximum for 2015.

Going from the last day of February, the biggest extent increase to the max was 498k, the 95th percentile is 388k, 81-10 average is 136k and several years hit their maximum in February.

With the 5 day average, 11 of the last 36 years would not beat the current max. That doesn't take into account that the 5 day average will probably drop for another few days at least. However given how much extra space we have, especially in the Bering sea and Okhotsk, and how only 1 in the last 10 years didn't hit their max in March, I'd still say there's a ~75% chance that we'll set a new max this month.
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on March 02, 2015, 02:24:48 PM
IJIS Extent:
13,827,443 km2 (01 March)
10,649,988 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Up 9,126 km2 from previous day.
Down 73,242 km2 over past seven days (daily average: -10,463 km2).
Up 9,126 km2 for the month of March (daily average: 9,126 km2).
820,649 km2 below 2000s average for this date.
362,354 km2 below 2010s average for this date.
219,490 km2 below 2014 value for this date.
700,351 km2 below 2012 value for this date.
Lowest March to-date average.
Lowest value for the date.
6 days this year (10% year-to-date) have recorded the lowest daily extent.
11 days (18.33%) have recorded the second lowest.
17 days (28.33%) have recorded the third lowest.
34 days (56.67%) in total have been among the three lowest on record.


CT Area:
13,087,684 km2 (01 March [Day 0.1616])
10,853,674 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Up 8,573 km2 from previous day.
Up 61,159 km2 over past seven days (daily average: 8,737 km2).
Up 8,573 km2 for the month of March (daily average: 8,573 km2).
552,195 km2 below 2000s average for this date.
132,852 km2 below 2010s average for this date.
39,822 km2 above 2014 value for this date.
143,094 km2 below 2012 value for this date.
4th lowest March to-date average.
4th lowest value for the date.
0 days this year (0% year-to-date) have recorded the lowest daily area.
1 day (1.67%) has recorded the second lowest.
5 days (8.33%) have recorded the third lowest.
6 days in total (10%) have been among the lowest three on record.

Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on March 02, 2015, 02:33:43 PM
BFTV,
It would be great to  see the entire series for March from now to the maximum to  see how likely  we are to get back up to the record low maximum extent.  On my  figures the average rise from now won't get  us back to the current maximum for 2015.

I maintain a couple of graphics showing just this information. One for IJIS extent:

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FnYJVBZ6.png&hash=e58ff73846c1c93b44eebb09f79117ca)

...and one for CT area:

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FIL8JwK3.png&hash=19284d337af40da383a661cb97f584e4)

A quick eyeball shows that, based solely on past years' performances, neither area nor extent may have yet maxed out, though it appears more likely with each passing day...
Title: Re: 2015 sea ice area and extent data
Post by: crandles on March 02, 2015, 04:43:38 PM
BFTV,
It would be great to  see the entire series for March from now to the maximum to  see how likely  we are to get back up to the record low maximum extent.  On my  figures the average rise from now won't get  us back to the current maximum for 2015.

If you want it in numbers,

16 of last 27 years do not go above prev max this year of 14.539
23 of 27 do not go above record minimum max of 14.671

This is a lot better odds for NSIDC extent numbers having already peaked than for CT area numbers despite their similarity - NSIDC 185k below previous peak this year vs CT area 187k below previous peak this year. You would think that 187k on smaller area numbers would be more significant, but perhaps extra variability means it isn't more significant.
Title: Re: 2015 sea ice area and extent data
Post by: Siffy on March 02, 2015, 04:50:39 PM
Forgive me if i'm being silly but isn't comparing to how the last x number of years ran from this point on kind of naive or futile? Weather patterns were different in those years in the run up towards their maximums and in that regards using those figures doesn't actually give you a good idea of what's likely to happen later?

I realize I'm probably preaching to the choir here so to speak but as long as the current weather patterns hold isn't it highly probable the maximum has already been reached?
Title: Re: 2015 sea ice area and extent data
Post by: crandles on March 02, 2015, 05:46:48 PM
Suggesting it will follow year X is a bit silly, it won't follow any year precisely. However if you compare to 36, this may well give a reasonable representation of the range of what is possible. This just assumes that what happens now is pretty much random due to weather.

I have wondered if we could do better though. If you did it from a point where the area/extent had fallen rapidly or risen rapidly in the past few days, it might be sensible to find years where that had also happened and only use those years. i.e. there could well be some autocorrelation rather than just random fluctuations. Either way you end up with probability distribution which cannot be falsified and would take a lot of data to show one such pdf was better than another pdf.

Title: Re: 2015 sea ice area and extent data
Post by: BornFromTheVoid on March 02, 2015, 05:47:33 PM
Siffy,

Yeah, comparing with another individual year isn't of much use. But to get an idea of the range of likely outcomes, it's ok I think. Weather patterns rarely hold for all that long anyway, and several other years have seen long plateaus and drops into the start of March, so our situation this year isn't entirely unique.

EDIT: Trying a simple way to perhaps improve the method, if you correlate the February extent with each other, then just use all the years that had a value of over 0.9 then you get an average increase of 157k to the maximum, while the top 5 correlated years gives 102k.
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on March 02, 2015, 06:29:34 PM
Forgive me if i'm being silly but isn't comparing to how the last x number of years ran from this point on kind of naive or futile? Weather patterns were different in those years in the run up towards their maximums and in that regards using those figures doesn't actually give you a good idea of what's likely to happen later?

I realize I'm probably preaching to the choir here so to speak but as long as the current weather patterns hold isn't it highly probable the maximum has already been reached?

I agree with crandles and BFTV that past performances are not a reliable indicator of future trends, as each year is indeed a different beast. However, as they also both noted, looking back at the entire dataset can give a rough idea of what's likely to occur--or, more to the point, what's not. So, you know, not silly. But YMMV.
Title: Re: 2015 sea ice area and extent data
Post by: viddaloo on March 02, 2015, 06:30:09 PM
Not that it's very important to 'predict' whether we'll max out later or not, but here's my take (related to IJIS extent):

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fd22d7v2y1t140g.cloudfront.net%2Fm_13648181_SwEJv2frwUdC.png&hash=432dd56c97197398e944b65ab37b694f)

This is the change in extent for 12 days ahead for 2008—2014. Assuming we're 'safe' if we get to day 13, or March 14th. Red line is 114617 km2, if we gain more, we have a new max extent. After yesterday, only two years — 2010 and 2014 — crossed the line. I'd therefore say there's a 5 in 7 chance that February 15th was the maximum extent this year. 2 in 7 say it comes later.
Title: Re: 2015 sea ice area and extent data
Post by: DavidR on March 02, 2015, 10:23:41 PM
For Cryosphere Today area numbers

following path of previous 36 years:

17 fail to get higher than 13.274 reached 11 data days ago
5 rise further but stay below 13.317 so 22 years paths keep this year as 2nd lowest maximum on record
2 rise to between 13.317 and 13.358 to be 3rd lowest maximum on record
4 rise to between 13.358 and 13.460 to be 4th lowest maximum on record
0 rise to between 13.460 and 13.487 to be 5th lowest maximum on record
8 rise to between 13.487 and 13.700 to be 6th lowest maximum on record (current 6th is 13.708)

average increase of last 10 or 36 year puts us 4th lowest maximum on record

If just use last 10 years, 4 show no rise past 13.274 peak. So just under half of the paths whether you use 10 years or 36 years.

These,and other figures quoted here suggest about a 25% chance of a significant rise putting the minimum extent /area  well above the record low. Well at least outside the lowest three.  This probability doesn't seem to have changed over the past 36 years, despite the high rises in area in 3 of the past 5 years.

I've been predicting a low minimum for a while because of the warmth of the Northern Pacific ocean and I  think I'll stick with that  prediction.
Title: Re: 2015 sea ice area and extent data
Post by: wili on March 03, 2015, 01:39:49 AM
rs has a new post on this topic: https://robertscribbler.wordpress.com/2015/03/02/arctic-sea-ice-flirts-with-new-record-lows-dragging-global-coverage-inexorably-down/

Arctic Sea Ice Flirts With New Record Lows Dragging Global Coverage Inexorably Down
Title: Re: 2015 sea ice area and extent data
Post by: viddaloo on March 03, 2015, 04:21:18 PM
Yesterday's drop raises the (red) bar somewhat (we now need a bigger gain to beat Feb 15), and it looks like after today, 2010 will be the only year to have such a big gain between now and March 13. With a 7–year sample (not cherry–picked, because it is the 7 latest years, and thus all post–2007 event years, which seems relevant) we will then probably be left with a 1 in 7 chance of reaching a later extent maximum than Feb 15. Barring of course a surprise gain today. Climate Reanalyzer looks very eager to melt Arctic ice for the next week or two, upping the odds of a 2010 gain. I'm thinking century drop before Tuesday 10th.
Title: Re: 2015 sea ice area and extent data
Post by: deep octopus on March 03, 2015, 04:35:07 PM
Century rise followed by (almost) century drop on NSIDC extent: 14.36605 millions km2 makes this a daily record low.
Title: Re: 2015 sea ice area and extent data
Post by: viddaloo on March 04, 2015, 05:36:20 AM
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fd22d7v2y1t140g.cloudfront.net%2Fm_13648181_SwEJv2frwUdC.png&hash=432dd56c97197398e944b65ab37b694f)

This is the change in extent for 12 days ahead for 2008—2014. Assuming we're 'safe' if we get to day 13, or March 14th. Red line is 114617 km2, if we gain more, we have a new max extent. After yesterday, only two years — 2010 and 2014 — crossed the line. I'd therefore say there's a 5 in 7 chance that February 15th was the maximum extent this year. 2 in 7 say it comes later.
Wow! Just two days later, not only did 2014 dip below the red line, even 2010 did:

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fd22d7v2y1t140g.cloudfront.net%2Fm_13651057_wrWsLEa5M7F6.png&hash=e05b2860a060ee1c88ae728a6da5eae4)

In my simplistic estimate model this means 0 of 7 chances of a higher IJIS max than Feb 15.

There are no years post–2007 that sport the amount of refreeze necessary from March 4 to 13, to take us higher than 13.94 million.
Title: Re: 2015 sea ice area and extent data
Post by: DavidR on March 04, 2015, 08:48:56 AM
Wow! Just two days later, not only did 2014 dip below the red line, even 2010 did:

In my simplistic estimate model this means 0 of 7 chances of a higher IJIS max than Feb 15.

There are no years post–2007 that sport the amount of refreeze necessary from March 4 to 13, to take us higher than 13.94 million.
NSIDC shows an extent increase after March 13th of 230 K km^2 in 2010. Rapid increases are quite common in March when bad weather hits. So I don't think we can be confident of this years maximum for a couple of weeks yet.

It would be interesting to know if anyone has plotted the distribution of the dates of maximums over all the data sets, and if so if any of the measures show a predominance of early or late maximums. My dataset (post 2007) suggests the CT Area has a tendency to late maximums and more frequent  rapid rises in March. But that's only 8  years.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on March 04, 2015, 08:59:12 AM
By PM i got the following question:

Quote
: Wipneus  March 01, 2015, 08:00:03
Jaxa AMSR2 data for 20150227 is similar, with Baffin dropping at the same rate as the Bering region. [...] Total Extent -112.4

I'm puzzled by this figure, as the official IJIS numbers do not indicate a century drop here.

What am I missing? Are you excluding lakes or other areas that I am not aware of?

First,  I calculate regional extent and area data from a number of satellite derived sea ice concentration data sets. I do this because:
- regional data is hard to get;
- area data is not provided;
- calculation details differ, e.g. is lake ice included?

Now the question why century yes/no, while they both use Jaxa data. Since in this time of the season concentrating on the largest peak is a study in noise, whether weather related or any uncertainty in the chain of measuring and analysis. Comparing my Jaxa data with the Jaxa/IJIS/IARC extent I can think of the following differences.

- there is no IJIS or IARC in my calculations. I do not know all the what's and the how's of what eaxctly they do;
- For the totals, I only include at this moment the 14 well known regions. Since the IJIS/IARC extent data are consistently well above mine, I guess they include all of the ice. It is not sufficient though, even including all the ice my calculations are still a bit below.
- timing: correlating changes in both measurements show that my calculations lag those of the IJIS/Jaxa numbers. A difference of 12 hours would explain my observations.
- Averaging, they seem to suggest that a 2 day averaging period is used (3 days for the Windsat era). There is no averaging in my calculations;
- the data source:  I am using Level 3 data from Jaxa, that is already processed to some degree. Level 2 data would be an option. I have no idea what the IJIS/IARC calculations use.
- homogenization: IJIS/IARC offer continuous data since 2002 even with different sensors. Some compensation for the differences is likely to make them comparable. Details are unknown.

I publish the data as soon as it is calculated, locations are summarized in this post. (https://forum.arctic-sea-ice.net/index.php/topic,1112.msg43110.html#msg43110)

For Jaxa, I use L3 sea ice concentration available here (http://gcom-w1.jaxa.jp/index.html), free registration required.



 
Title: Re: 2015 sea ice area and extent data
Post by: viddaloo on March 04, 2015, 09:01:49 AM
NSIDC shows an extent increase after March 13th of 230 K km^2 in 2010. Rapid increases are quite common in March when bad weather hits. So I don't think we can be confident of this years maximum for a couple of weeks yet.

DavidR, we're already 2% down or 204K since the max, plus you must remember that 2010 is an extreme outlier year. But even if 2010's refreeze path was to be chosen this year after March 13th, we will be low enough on March 13th to not go above Feb 15 and 13.94.
Title: Re: 2015 sea ice area and extent data
Post by: DavidR on March 04, 2015, 09:20:15 AM
DavidR, we're already 2% down or 204K since the max, plus you must remember that 2010 is an extreme outlier year. But even if 2010's refreeze path was to be chosen this year after March 13th, we will be low enough on March 13th to not go above Feb 15 and 13.94.
viddaloo,
in NSIDC records 3 of the past 8 years show extent gains of around 300 K km^2 after March 2nd so I don't think 2010 is that extreme an outlier. It just depends when the icy blast comes, if indeed it  does.

I  have to  say I don't expect it to, and have predicted a near record low maximum for about a month.
http://forum.arctic-sea-ice.net/index.php?action=post;topic=997.msg44884;quote=44884 (http://forum.arctic-sea-ice.net/index.php?action=post;topic=997.msg44884;quote=44884)
Title: Re: 2015 sea ice area and extent data
Post by: viddaloo on March 04, 2015, 09:38:36 AM
I see. But you'd now have to look at March 4th or after. Every day counts at this time of year, particularly when 2015 has a major drop on March 3rd, and half of that on the 2nd.

My point being: Even 300k as a potential gain before March 13th will hardly be a match for 2015, as we're already this low and at least a week ahead will be extremely mild in the Arctic. We'll go lower than 300k below Feb 15th, therefore the ~11th to 13th gain would have to be gigantic.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on March 04, 2015, 09:54:55 AM
Next questions:

Quote
with a lot of focus these days on record lows, amid huge differences in the estimates between NSIDC and IJIS, that both claim to measure >= 15% ice concentration, maybe you could just briefly point out why they differ, too? I know I would be curious to read that!


Let me talk about Jaxa instead of IJIS. IJIS and IARC seem to have been removed from all the graphs and website.

- NSIDC is using SMMR, SSM/I and SSMIS instruments on several instruments. Jaxa has used since 2002 the AMSR-E, Windsat and AMSR2 data.;
- NSIDC data is a single data set, explicitly homogenized for climatic purposes. I have serious doubts about Jaxa's homogenization;
- NSIDC uses the "Nasa Team" algorithm. Jaxa the "bootstrap" algorithm;
- NSIDC uses a 25km grid. Jaxa probably used a 12.5 km grid, an since AMSR2 10km;

Most of the differences in extent are probably explained by the last point: extent increases with a courser grid and gives more false ice due to the land spillover effect. The effect on area is much smaller, NSIDC area is mostly below that of Jaxa.

Quote
And if you will: Why should anyone use NSIDC rather than IJIS, or the other way around?

I don't doubt Jaxa ( I am not sure if calling it IJIS is still appropriate) is currently the most accurate available. The uncertainties start to get bigger before 2013. So for comparison with previous years (anything except 2013 and 2014) NSIDC should be used. Especially when searching for records I would add.


BTW I notice now the claim for 15% cut-off is explicitly for AMSR-E. Thus opening the possibility that another threshold is used, I can remember some suggestion that the AMSR2 is accurate enough to lower the limit to 8%. Interesting research subject.
Title: Re: 2015 sea ice area and extent data
Post by: Neven on March 04, 2015, 10:23:55 AM
(https://lh4.googleusercontent.com/-mk6saeS2svM/VPbOjsaLN7I/AAAAAAAACF4/0UgcRQsQMQs/s800/IJISSIE20150303.png)

Very interesting developments. I wonder two things: What will PIOMAS do with all this, and when will it bounce up again, and by how much? OK, that's three things.
Title: Re: 2015 sea ice area and extent data
Post by: lanevn on March 04, 2015, 11:41:57 AM
Very interesting developments. I wonder two things: What will PIOMAS do with all this, and when will it bounce up again, and by how much? OK, that's three things.

I think NSIDC will help to PIOMAS - their vision is slighty different from ijis )
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on March 04, 2015, 01:41:53 PM
IJIS Extent:
13,738,251 km2 (03 March)
Down 203,809 km2 (1.46%) from 2015 maximum-to-date of 13,942,060 km2 on 15 February.
If extent were to follow the same path from today forward that it did in 2004, 2010, or 2014, we'd see a new 2015 maximum. Only 2010 and 2014 saw enough extent increase from today onward to break the 14 million mark.
10,560,796 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Down 59,898 km2 from previous day.
Down 174,601 km2 over past seven days (daily average: -24,943 km2).
Down 80,066 km2 for the month of March (daily average: -26,689 km2).
927,010 km2 below 2000s average for this date.
483,821 km2 below 2010s average for this date.
388,642 km2 below 2014 value for this date.
957,696 km2 below 2012 value for this date.
Lowest March to-date average.
Lowest value for the date.
8 days this year (12.9% year-to-date) have recorded the lowest daily extent.
11 days (17.74%) have recorded the second lowest.
17 days (27.42%) have recorded the third lowest.
36 days (58.06%) in total have been among the three lowest on record.


CT Area:
13,144,496 km2 (03 March [Day 0.1671])
Down 130,059 km2 (0.98%) from 2015 maximum-to-date of 13,274,555 km2 on 17 February [Day 0.1288].
10,910,487 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Up 7,473 km2 from previous day.
Up 13,650 km2 over past seven days (daily average: 1,950 km2).
Up 65,385 km2 for the month of March (daily average: 21,795 km2).
559,098 km2 below 2000s average for this date.
122,193 km2 below 2010s average for this date.
229,893 km2 above 2014 value for this date.
315,543 km2 below 2012 value for this date.
4th lowest March to-date average.
4th lowest value for the date.
0 days this year (0% year-to-date) have recorded the lowest daily area.
1 day (1.61%) has recorded the second lowest.
5 days (8.06%) have recorded the third lowest.
6 days in total (9.68%) have been among the lowest three on record.

Title: Re: 2015 sea ice area and extent data
Post by: OldLeatherneck on March 04, 2015, 09:19:17 PM
While I seldom have , or take, the time to comment on this Forum, I'm still avidly following events in the Arctic on a daily basis.  While only a fool would take the current IJIS/JXA Extent to make any prediction about what the final minimum will be in September, it is time to make some reasonable predictions about the 2015 Maximum Extent.

In order for 2015 to not have the lowest IJIS/JAXA Extent on record, it would have to gain another 389,478 Km2.  In my humble opinion, I do not see anyway that will happen in the next 10-15 days.

In order for  the 2015 IJIS/JAXA Maximum Extent to exceed 14M Km2 would require a gain of another 261,749 Km2.. I find this to be highly improbable considering the  state of the ice and the near-term predictions of other commenters.

In order for  the 2015 IJIS/JAXA Maximum Extent to occur later than February 15th, it would have to gain more than 203,809 Km2.  While not impossible to happen this time of year, I  consider this unlikely.

If the 2015 IJIS/JAXA Maximum Extent turns out to be the  13,942,060 Km2, not only will it be the lowest on record, it will be first time below 14M Km2, and the earliest to have ever occurred.  The denialists will have trouble explaining this away, although I trust them to say someting irrelevant or blatantly false.

What does this mean for the remainder of March.  The lowest IJIS/JAXA Extrent ever measured in March was 13,569,042 Km2. on march 30th, 2006.  For 2015 to have a lower Extent than that this month only requires a loss of an additional loss of 169,209 Km2.  Average Extent loss from this date through March 31st for years 2003-2014 was 238,420 Km2.  The only years that did not achieve that were 2010, 2011 (w/gains) and 2012 with a loss of only 165 Km2.  The fact that those were 3 of the  past 5 years may or may not be relevant.....I do not know.


       
            
Title: Re: 2015 sea ice area and extent data
Post by: Buddy on March 04, 2015, 10:47:13 PM
One thing I would be curious to see....and someone may have already done it.....is to chart the number of days between (a) the date of the winter maximum, and (b) the date of the following minimum.

Over time.....I assume that number has decreased.  And going forward over coming years and decades....I assume that number will SHRINK further.   Certainly the last 15 - 20 years would be fascinating.
Title: Re: 2015 sea ice area and extent data
Post by: DavidR on March 05, 2015, 02:10:56 AM
One thing I would be curious to see....and someone may have already done it.....is to chart the number of days between (a) the date of the winter maximum, and (b) the date of the following minimum.

Over time.....I assume that number has decreased.  And going forward over coming years and decades....I assume that number will SHRINK further.   Certainly the last 15 - 20 years would be fascinating.

You  can see the range here.
https://sites.google.com/site/pettitclimategraphs/sea-ice-area#asiammdpdsb
There doesn't appear to be any significant trend, winter and summer aren't really shifting much.

If this years maximum date stays at 17th Feb it  will be the earliest maximum in the record.
Title: Re: 2015 sea ice area and extent data
Post by: OldLeatherneck on March 05, 2015, 12:10:13 PM
This almost qualifies for "Shocking News".  I compared the Extent value on March 4th, this year (2015) to March 31st of previous years. Only 2006 had a lower March 31st Extent than March 4th of this year!!

It seems that we are about 4 weeks ahead of schedule.

  Date           Year          EXTENT
March 31st       2006       13,575,600
March 4th   2015    13,688,997
March 31st       2007       13,714,811
March 31st       2005       13,838,113
March 31st       2014       13,877,174
March 31st       2011       13,968,366
March 31st       2013       14,222,135
March 31st       2009       14,234,871
March 31st       2004       14,271,527
March 31st       2008       14,370,732
March 31st       2012       14,530,807
March 31st       2003       14,687,712
March 31st       2010       14,688,540

Title: Re: 2015 sea ice area and extent data
Post by: Buddy on March 05, 2015, 12:22:05 PM
That is rather startling.  And the next week will be VERY WARM over a large chunk of the Arctic.  This is really setting up as an "ugly year" for the Arctic.  Amazing what warming oceans can do.

I said 3 years ago that the Arctic would "melt out" except for a few hundred mile strip along the Canadian Archipelago....by September of 2016.....and I have little doubt that will indeed happen.

Too much warming water attacking the ice from all sides......
 
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on March 05, 2015, 01:35:41 PM
Keeping in mind that springtime performance is in no way a reliable indicator of the summer minimum, it's still startling to see that, as of today, extent is more than one million square kilometers lower than it was on this same date in 2012. That's nearly the size of California and Texas combined:

04 March 2012: 14,699,717 km2
04 March 2015: 13,688,997 km2

It's important to remember that even 2014 experienced a number of record daily lows in February and March, and that most of the daily record lows for April and May are still held by 2006. 2012--the Arctic sea ice's annus horribilis--didn't move into record territory for good until June, so any predictions made now should be taken with a huge grain of salt.

But, still; a million km2. Yikes...
Title: Re: 2015 sea ice area and extent data
Post by: richie3846 on March 05, 2015, 01:46:25 PM
I've been 'lurking' on this board for a couple years now - this is my first post as I don't normally have much to add to the in-depth scientific knowledge some of the posters have. I suppose you could call me a layman.

Buddy, I am on your side with this one.  I reckon we are looking at virtually ice free over the next 1-2 years. I try not to get bogged down with the details on this board, but take a 'macro' view instead. Some readers of the board may be interested in taking a look at:

http://www.ncdc.noaa.gov/sotc/global/2014/13 (http://www.ncdc.noaa.gov/sotc/global/2014/13)

What is of particular interest is the fact that the oceans last year were the warmest on record. I know weather conditions can sometimes go against the general trends, but the chances of recording the smallest maximum must surely be greatly amplified by the warm seas. I think we may have 'perfect storm' conditions for ice melt now, because of the warm seas and the possibility of El Nino making an appearance at some point this year. Of course weather conditions could still be favourable for ice retention, but there is a lot of heat already locked away, especially, it seems, in the northern hemisphere.

I wonder if there is any direct correlation between the global annual sea temperature and the minimum/maximum sea ice levels?
Title: Re: 2015 sea ice area and extent data
Post by: Buddy on March 05, 2015, 02:28:53 PM
We humans really are pathetic sometimes.  We fail to see the most obvious things that are right in front of our face....if we would just look (and that certainly includes me).

The next few weeks will certainly be interesting.....as we chart the 2015 ice extent.  I expect it to continue to drop....and run parallel, but significantly below the other "low years".  It IS a "future event"....and while none of us know EXACTLY WHEN.....we all know WHERE we are headed.

2015 could very well end up between 1 mill and 2 mill km2.  Do we know that for sure?  Certainly not.  Do we KNOW that as CO2 levels continue to rise, that the temp of the planet continues to rise.....and that the ice sheets will continue to melt.  WE CERTAINLY DO.

The day is coming closer and closer that people that have been lying like Joe Bastardi, Anthony Watts, Sean Hannity, FOX News, and LONG LIST of politicians........are going to have to come up with some answers for their behavior.  The "dark side" of me is going to relish that.



Title: Re: 2015 sea ice area and extent data
Post by: Meirion on March 05, 2015, 05:03:07 PM
In terms of the minimum this is the only graph that matters in the short term IMHO. The number of days over 271 Kelvin North of 80 North gives pretty good prediction. Last two years despite high temps in winter short cold high Arctic summer led to increases in ice volume despite fragile state of Arctic. I think we've had a couple of freak years weather wise and if we're above 271 much earlier than day 150 this year it will be interesting. If 2015 is repeat of 2013 & 2014 the possibility of an unknown negative feedback loop becomes stronger.


http://ocean.dmi.dk/arctic/meant80n.uk.php (http://ocean.dmi.dk/arctic/meant80n.uk.php)

Title: Re: 2015 sea ice area and extent data
Post by: viddaloo on March 05, 2015, 05:15:04 PM
If 2015 is repeat of 2013 & 2014 the possibility of an unknown negative feedback loop becomes stronger.

That 'unknown' negative feedback would be increase in wildfires caused by a warming sub–arctic taiga area, again causing more 'fog' or smoke over sea ice, IMnsHO.
Title: Re: 2015 sea ice area and extent data
Post by: wili on March 05, 2015, 05:32:41 PM
Wouldn't any such smoky shading be a fairly short-term negative but longer-term positive feedback, as soot drops on the ice and changes albedo? (Not to mention the yet-longer-term effect of the GHGs released.)
Title: Re: 2015 sea ice area and extent data
Post by: viddaloo on March 05, 2015, 05:38:51 PM
I'm certainly no expert, but I believe soot etc falls out of the sky locally near the fire before wildfire smoke travels thousands of miles to the CAB and stays airborn longer than the larger soot particles? Regarding short–term, you only need to shade the worst insolation period, the 10–15 weeks around Summer Solstice, to have a huge effect. And wildfires burn naturally in that same 'short–term' period, exactly around Solstice. Could very well be a negative feedback, IMO. Question is if it will be sufficient to save us.
Title: Re: 2015 sea ice area and extent data
Post by: crandles on March 05, 2015, 06:13:18 PM
NSIDC extent 14.33513 lower than 23 of the last 24 days.

following movements in extent of last 27 years,

21 of last 27 years do not go above prev max this year of 14.539
26 of 27 do not go above record minimum max of 14.671
Title: Re: 2015 sea ice area and extent data
Post by: Bob Wallace on March 05, 2015, 07:01:12 PM
Throw into the mix of accelerating forces the condition of the ice.

We no longer have massively thick sheet of solid ice but more "slush".  Those smaller pieces are going to be more easily transported out where they will quickly melt.

I'm betting 2015 will be the 'Year of the Big Flush'.  All we need is some wind to make it happen.
Title: Re: 2015 sea ice area and extent data
Post by: jdallen on March 05, 2015, 07:21:51 PM
Meirion - temp in this case is an effect not a cause.  The key is insolation. heat in the atmosphere actually transfers very little energy to the ice, and exposed sea water would tend to keep temperatures down, in part due to evaporation.

Again, the threat this summer and my concern is tied to *many* factors, current temperatures being just one.
Title: Re: 2015 sea ice area and extent data
Post by: jdallen on March 05, 2015, 07:35:25 PM
Keeping in mind that springtime performance is in no way a reliable indicator of the summer minimum, it's still startling to see that, as of today, extent is more than one million square kilometers lower than it was on this same date in 2012. That's nearly the size of California and Texas combined:

04 March 2012: 14,699,717 km2
04 March 2015: 13,688,997 km2

It's important to remember that even 2014 experienced a number of record daily lows in February and March, and that most of the daily record lows for April and May are still held by 2006. 2012--the Arctic sea ice's annus horribilis--didn't move into record territory for good until June, so any predictions made now should be taken with a huge grain of salt.

But, still; a million km2. Yikes...
I get your skepticism based on the behavior of 2006 and 2012.  I'll point out that (1) the ice is much different and (2) the amount of heat generally in the arctic has continued  rise.  Weather and feedbacks will undoubtedly come more into play in spring, as paradoxically, the same moisture retaining heat now will start to buffer incoming heat.  But yah, yikes! 1 million KM2 lower will make protection of the remaining extent much harder, much earlier.  More open water will make up for some of the recent lack of melt ponds.

Personally, I think it's going to be a crazy season.
Title: Re: 2015 sea ice area and extent data
Post by: viddaloo on March 05, 2015, 07:47:16 PM
Soot from wildfires landing on snow–free tundra will be *below* the new snow that falls in autumn, and thus won't contribute to increased melting. On the contrary, the smoke will save thousands of cubic kilometers of sea ice from midsummer melt, in turn causing higher albedo in the CAB.
Title: Re: 2015 sea ice area and extent data
Post by: LRC1962 on March 05, 2015, 10:28:24 PM
Soot from wildfires landing on snow–free tundra will be *below* the new snow that falls in autumn, and thus won't contribute to increased melting. On the contrary, the smoke will save thousands of cubic kilometers of sea ice from midsummer melt, in turn causing higher albedo in the CAB.
I have lived in a snow country most of my life, Canada, Although I have not made a study of it, I have never witnessed that behavior myself. One part is that of increased albedo with new snow. It seems you are presuming no new fires. Fire season all over the Arctic region is  getting longer and starting earlier. More fires more soot. Also the soot coming from China is getting more and more dense and can easily be seen from space stretching farther and farther from China. I suspect you will find some of landing on that fresh snow and mixed in it as it falls, making it dirty snow. As for the fresh snow not getting impacted by a lower layer of soot? If any melt occurs all I have seen is that very quickly the lower dirty snow gets mixed in with the new snow very quickly.
Another issue that is getting into play more and more is that you have very little ice left that is saline free. 10 years ago old MYI would have been. Now most ice that is labeled MYI is in fact ridged ice that has been compacted together all of which has a fair amount of saline in it still.
Any study I have seen about saline ice is that air, water and particulates travel freely up and down its depth until the salt has been pressed out of it, and that does not happen until 3+ yr old ice. As I stated before, we have very little of true MYI left.
Jason Box is seeing the same thing on the Greenland ice sheets. old soot is getting added to new soot and that is why the sheets are getting darker and darker.
Title: Re: 2015 sea ice area and extent data
Post by: DavidR on March 05, 2015, 10:31:28 PM
Since 2007 the increase to date from Feb 1st looks like this: (1000 km^2)
   Max: 1221
   Ave:   675
   Min:    455
   2015: 121

We need rises above 265 to not be at record lows for the next three days and above 190 to not be at record lows for the next six.

The one positive thing in this gloomy outlook is that although the ice may  not have been extending it may  have been consolidating, so the melt  may be slowed. However with the winds and warmth we have seen over the past month even that may not have occurred.  Certainly the thickness estimates are looking appalling low.

I expect the PIOMAS figures for February  will give us a good indicator of where we are going.

Title: Re: 2015 sea ice area and extent data
Post by: viddaloo on March 05, 2015, 10:57:37 PM
As for the fresh snow not getting impacted by a lower layer of soot? If any melt occurs all I have seen is that very quickly the lower dirty snow gets mixed in with the new snow very quickly.

Seriously, if you get a meter or two of snow on top of some ash and soot that is on the bare tundra ground underneath all that snow, that is not going to affect the albedo or melting of that snow. The meters of snow melt from the top down, not the other way around. When melt gets down to the soot there is no more snow to melt. That's why I say soot on the bare tundra does not increase snow melt. The soot is under the snow and the sun does not know about it until it's too late to melt already melted snow.
Title: Re: 2015 sea ice area and extent data
Post by: LRC1962 on March 05, 2015, 11:21:04 PM
Sorry about missing the point of you talking about tundra. Point of fact there is virtually no more year round snow left in the tundra anywhere. Granted this year there was quite a bit of snow fall but I can not see it sticking around for long as the ground is no longer frozen until you get deeper down. The soot I was thinking about was on the ice itself. Another point is that in isolated spots you may get meters of snow on a bad snow winter, but for the most part you measure tundra snow by the cm. reason is the wind may blow the snow around so much you can not see but accumulations in an Arctic blizzard normally are in the 2-4 cm range. Only in the lower latitudes such as the US-Canadian border do you get blizzards that bring in accumulations of 60cm+.
Title: Re: 2015 sea ice area and extent data
Post by: viddaloo on March 05, 2015, 11:31:13 PM
Yup, I sort of figured there had to be some major misunderstanding there! :D

Pardon me, I'm from the West of Norway. I've just been a week literally digging our cottage out of 3 or 4 meters of snow. Not foot or feed or yards or inches. Meters. The landscape is 'alpine tundra' but the precipitation is just absurdly high.

I do admit I'm uncertain about the particle size and flight ability of 'soot', 'black carbon' and the like. But I'm pretty sure smoke stays longer in the air than bigger particles. And I know frost fog forms more easily around smoke particles, so that may be key to slow summer melt in the Arctic.
Title: Re: 2015 sea ice area and extent data
Post by: OldLeatherneck on March 06, 2015, 12:00:42 AM
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi1269.photobucket.com%2Falbums%2Fjj597%2FOldLeatherNeck%2Fca7866f3-b3ea-4040-8fa1-53fb1db1ecd1_zpssphrl4ts.jpg&hash=5ab0a1a3a36b498ca9a551fea517fe1c)

Just to have some fun, I thought I'd run some projections, thru April based prior years data.  I used all years from 2003 - 2014, looking at gains/losses for 4 time frames; the first 15 days of March, the last 16 days of March, the first 15 days of April and the last 15 days of April.  What somewhat surprised me was that during  the first half of March there was an average daily gain of almost 1,900 Km2 followed in the second half of March with an average daily loss of almost 6,900 Km2.  I was equally surprised to see how linear the average daily losses were in April with the first half losing just over 38,000 Km2 during the first half and just over 39,000 during the second half of the month.

Using the average gain/loss for each of the 4 time frames I plotted 3 projected scenarios; 1 using 10% less than the average, 1 using the average and 1 using 10% more than the average for each day.  To plot the extreme MIN and MAX scenarios, for each time frame, I selected data from the year having the Best Case and the year having the Worst Case data. For Example:

1.  For the first half of March, 2013 had an average daily gain of only 1,601 Km2 and 2014 had an average daily loss of 24,216 Km2.
2. For the last half  of April, 2007 had an average daily loss of 23,872 Km2 and 2012 had an average daily loss of 60,507 Km2.

What I am most concerned about right now is what will happen in the next 10-12 days.  In reading comments on this and other threads, it appears that this ice is thinner this year, the Arctic temps will remain high for the next week and there may be a cyclone on the way.  This it makes it unlikely that there will be in net Extent gain between now and the middle of March. If it turns out that there are significant Extent losses in the next few weeks almost any scenario will keep 2015 in close contention with 2007, 2011 and 2015.

We may be entering uncharted waters (without the ice!!)
Title: Re: 2015 sea ice area and extent data
Post by: viddaloo on March 06, 2015, 12:53:28 AM
We may be entering uncharted waters (without the ice!!)

Not if we can all just agree to use NSIDC extent and forget about JAXA:

- NSIDC uses a 25km grid. Jaxa probably used a 12.5 km grid, an since AMSR2 10km;

Most of the differences in extent are probably explained by the last point: extent increases with a courser grid and gives more false ice due to the land spillover effect.

Through our choice of the NSIDC metrics we can artificially add about 0.7 million km2 of 'ghost ice' or only–in–a–computer ice. Where is this seemingly bountiful and free extra ice? Only on computer hard–drives. But if we all *believe* that ice to be real, our common faith energy may just make it so.
Title: Re: 2015 sea ice area and extent data
Post by: jdallen on March 06, 2015, 01:40:11 AM

Just to have some fun, I thought I'd run some projections, thru April based prior years data.

<snippage>

1.  For the first half of March, 2013 had an average daily gain of only 1,601 Km2 and 2014 had an average daily loss of 24,216 Km2.
2. For the last half  of April, 2007 had an average daily loss of 23,872 Km2 and 2012 had an average daily loss of 60,507 Km2.

What I am most concerned about right now is what will happen in the next 10-12 days. 

<snippage>

We may be entering uncharted waters (without the ice!!)

Interesting modeling, Old Leatherneck.

In a word, YES.

Much less the last few years, I don't think there's been weather and ice conditions like this in the Arctic for centuries, probably hundreds of millennia.

We are definitely in uncharted waters.
Title: Re: 2015 sea ice area and extent data
Post by: OldLeatherneck on March 06, 2015, 11:55:48 AM
JAXA Extent March 5th - 13,664,797 Km2 - Down 24,200 Km2

Down 153,520 Km2 in the first 5 days of March for an average loss of   30,704 Km2 per day.

The typical March has Extent undulating up and down, with the first half of the month slightly gaining Extent and the last half  of the month beginning to trend downwards. 
Title: Re: 2015 sea ice area and extent data
Post by: OldLeatherneck on March 06, 2015, 01:26:17 PM
Average JAXA Extent (2003-2014)
12-Apr      13,760,053
13-Apr      13,714,346
14-Apr    13,679,265      5 March 2015   13,664,797
15-Apr      13,638,698
16-Apr      13,593,635


It would appear that we are about 5 weeks ahead of where we should be!!
Title: Re: 2015 sea ice area and extent data
Post by: Jim Hunt on March 06, 2015, 01:58:33 PM
It would appear that we are about 5 weeks ahead of where we should be!!

Don't forget that I was ultimately forced to eat lots of crow stew around this time last year!

http://forum.arctic-sea-ice.net/index.php/topic,778.msg21702.html#msg21702 (http://forum.arctic-sea-ice.net/index.php/topic,778.msg21702.html#msg21702)
Title: Re: 2015 sea ice area and extent data
Post by: Shared Humanity on March 06, 2015, 02:11:45 PM
In terms of the minimum this is the only graph that matters in the short term IMHO. The number of days over 271 Kelvin North of 80 North gives pretty good prediction. Last two years despite high temps in winter short cold high Arctic summer led to increases in ice volume despite fragile state of Arctic. I think we've had a couple of freak years weather wise and if we're above 271 much earlier than day 150 this year it will be interesting. If 2015 is repeat of 2013 & 2014 the possibility of an unknown negative feedback loop becomes stronger.


http://ocean.dmi.dk/arctic/meant80n.uk.php (http://ocean.dmi.dk/arctic/meant80n.uk.php)

I would not be surprised if this pattern of warmer Arctic winters and cooler Arctic summers persist and I think that both are related to the same shifts in climate we are seeing. We are having more and more frequent incursions of mid latitude systems into the polar north. In the winter this brings warmth and moisture. In the summer, we are seeing dramatically increasing moisture and cloud cover which reduces the impact of the sun on ice  melt.
Title: Re: 2015 sea ice area and extent data
Post by: viddaloo on March 06, 2015, 02:25:18 PM
Average JAXA Extent (2003-2014)
12-Apr      13,760,053
13-Apr      13,714,346
14-Apr    13,679,265      5 March 2015   13,664,797
15-Apr      13,638,698
16-Apr      13,593,635

It would appear that we are about 5 weeks ahead of where we should be!!

That truly is amazing, OldLeatherneck. Also, if you look more narrowly at the present champion 2012, we appear to be about 7 ½ weeks ahead (Apr 25 – 13560700 km2).
Title: Re: 2015 sea ice area and extent data
Post by: Siffy on March 06, 2015, 03:42:32 PM
It would appear that we are about 5 weeks ahead of where we should be!!

Don't forget that I was ultimately forced to eat lots of crow stew around this time last year!

http://forum.arctic-sea-ice.net/index.php/topic,778.msg21702.html#msg21702 (http://forum.arctic-sea-ice.net/index.php/topic,778.msg21702.html#msg21702)

Well, I won't say it's impossible but I find it highly unlikely we will see a large enough upswing later to see a new maximum emerge.
Title: Re: 2015 sea ice area and extent data
Post by: oren on March 06, 2015, 04:04:26 PM
The story goes beyond just the total extent number. Looking at the different regions, most of the missing extent is in Bering and Okhotsk, basically the Pacific is too warm for proper ice formation. This is a significant change from previous years, as far as I can tell by layman methods. What effect will this have on the rest of the ice pack?
As the Pacific area melts earlier in the season, this could simply mean less melt later, resulting in a normal melt year.
On the other hand, large quantities of warm water entering through Bering Strait could cause havoc for the rest of the pack, especially in the ESS which is a swing area between high melt and low melt years.
Any thoughts?
Title: Re: 2015 sea ice area and extent data
Post by: deep octopus on March 06, 2015, 04:15:41 PM
Nearly 110,000 km2 loss on NSIDC extent overnight. Although we have seen this story before (as with last year) of a slow March start and a sudden surge to a new maximum later in the month, with each passing day, the chance for the Arctic to finish its freeze season in the best of conditions possible is escaping. From the AMSR2 graphics, the largest change I'm noticing this month is the retreat of ice in Barents, whereas Bering and Okhotsk are generally holding their ground for now. However, I think those fringe Pacific regions will not matter as much, as what little ice exists there will be the among the first to vanish anyway come April and May, particularly under a warm PDO regime where I suspect losses on the Pacific side will be more advanced, all things being equal, with the advection of warm water. Early losses in Barents is what I would find more disturbing. Seeing what the next few weeks bring us... We're already well below 2011 on NSIDC.
Title: Re: 2015 sea ice area and extent data
Post by: OldLeatherneck on March 06, 2015, 04:37:15 PM
It would appear that we are about 5 weeks ahead of where we should be!!

Don't forget that I was ultimately forced to eat lots of crow stew around this time last year!

http://forum.arctic-sea-ice.net/index.php/topic,778.msg21702.html#msg21702 (http://forum.arctic-sea-ice.net/index.php/topic,778.msg21702.html#msg21702)

Jim,

I've eaten a lot of decaying crows in my lifetime.  However, knowing how fickle the Arctic can be I will only produce projections that go out 6-8 weeks in advance and I will not claim them to be robust scientific models,,,,just a toy I'll play with from time to time.
Title: Re: 2015 sea ice area and extent data
Post by: crandles on March 06, 2015, 05:00:08 PM
Of last 27 years only one, 1997 gains enough to get NSIDC extent above 14.539 reached on 22 Feb. Following that year's movements would reach 14.58 still 90k below record low maximum of 14.67
Title: Re: 2015 sea ice area and extent data
Post by: jdallen on March 06, 2015, 05:49:14 PM
Of last 27 years only one, 1997 gains enough to get NSIDC extent above 14.539 reached on 22 Feb. Following that year's movements would reach 14.58 still 90k below record low maximum of 14.67
The probability of us reaching 14, much less the old record, is decreasing rapidly. Meanwhile, the weather looks increasingly unfavorable.

Five weeks ahead sounds about right.  The key is timing; we are running into increasing insolation with that running start, which has the potential to massively increase heat uptake in the region regardless of cloud cover. Keep in mind we are looking at nearly a million KM2 where the albedo has been cut from about .85 down to about .15; that's a rather large shift in energy budget, even on the periphery.  Even with and utterly favorable year with only about 10 million KM2 of melt (in line with 13/14), we are still looking at a minimum well under last year, and possibly under 4 million KM2 extent at minimum.

To stay above that would require a two sigma shift in weather behavior against trend.  I don't see how that can happen. We could pray for another Pinatubo, I suppose....

Even an average year (~10.5 million km2 melt) takes us close to 2012 territory.

The clear danger is, we stand to be in "normal" minimum territory next summer by the middle of August, with five weeks of insolation left to drive the ice down further. I find the potential for that quite alarming.

Yes, we have all eaten crow, but again, I think last time, we were just looking at the ice, not the timing, nor the heat budget.  Things are rather different now.

That's what I think the five week running start portends....
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on March 07, 2015, 01:35:33 PM
IJIS Extent:
13,660,208 km2 (06 March)
Down 281,852 km2 (2.02%) from 2015 maximum-to-date of 13,942,060 km2 on 15 February.
10,482,753 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Down 4,589 km2 from previous day.
Down 175,350 km2 over past seven days (daily average: -25,050 km2).
Down 158,109 km2 for the month of March (daily average: -26,352 km2).
1,008,374 km2 below 2000s average for this date.
602,359 km2 below 2010s average for this date.
594,932 km2 below 2014 value for this date.
1,004,739 km2 below 2012 value for this date.
Lowest March to-date average.
Lowest value for the date.
11 days this year (16.92% year-to-date) have recorded the lowest daily extent.
11 days (16.92%) have recorded the second lowest.
17 days (26.15%) have recorded the third lowest.
39 days (60%) in total have been among the three lowest on record.


CT Area:
13,028,595 km2 (06 March [Day 0.1753])
Down 245,960 km2 (1.85%) from 2015 maximum-to-date of 13,274,555 km2 on 17 February [Day 0.1288].
10,794,586 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Down 62,573 km2 from previous day.
Down 63,911 km2 over past seven days (daily average: -9,130 km2).
Down 50,516 km2 for the month of March (daily average: -8,419 km2).
685,771 km2 below 2000s average for this date.
288,603 km2 below 2010s average for this date.
16,443 km2 above 2014 value for this date.
651,877 km2 below 2012 value for this date.
4th lowest March to-date average.
4th lowest value for the date.
0 days this year (0% year-to-date) have recorded the lowest daily area.
1 day (1.54%) has recorded the second lowest.
5 days (7.69%) have recorded the third lowest.
6 days in total (9.23%) have been among the lowest three on record.

Title: Re: 2015 sea ice area and extent data
Post by: crandles on March 07, 2015, 03:09:56 PM

That's what I think the five week running start portends....

A five week running start as of now taking us just past day 100 where temperatures are 15C below freezing

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Focean.dmi.dk%2Farctic%2Fplots%2FmeanTarchive%2FmeanT_2015.png&hash=0d8b9fb4dbdb5645028d5aadebcb05c2)

is nowhere near the same as a 5 week running start as at day 140
Title: Re: 2015 sea ice area and extent data
Post by: Revillo on March 07, 2015, 04:13:25 PM
Forgive me if I'm way off the mark, but I haven't seen this trend explicitly mentioned and I'm wondering if others think it holds any weight.

It would seem that there is a tight relationship between el niño events and arc sea ice extent response. The first year following an el niño, we tend to see very low winter maximums (2006, 2011), followed by a significant but unexceptional melt season. Two years after, we see an increase in maximum (2007, 2012) followed by a summer blowout with catastrophic melting. I'm guessing this would be due to predictable circulation of ocean currents transporting warm water from the Pacific into the Arctic.

While 2014 was not officially an el niño year, there was an enormous swath of positive temp anomalies throughout the Pacific that could very well lead to the same results with regards to the Arctic, and so I believe 2015 can be compared to the 2006 / 2011 seasons, and therefore I do not predict a  major blowout to come until next summer. 

Interestingly, the PDO activity happening now looks like a different beast than other recent el niños in that, while not exceptionally pronounced, is steadier and longer lasting. Others have suggested a phase change has occurred in the PDO towards sustained release of heat for the next decade or two.
If the heat keeps up, we could see seasons both with record low maximums and minimums starting as early as next year and continuing for quite some time...
Title: Re: 2015 sea ice area and extent data
Post by: seaicesailor on March 07, 2015, 04:22:32 PM
Interesting. I wouldnt call 2011 melt season unexceptional though.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on March 07, 2015, 05:34:30 PM
I was asked about my estimated CT area changes for the next few days. Here we go:

From area calculated from NSIDC sea ice concentration I expect the following changes of  CT-area:

Sun: -13k
Mon: +18k

Title: Re: 2015 sea ice area and extent data
Post by: viddaloo on March 07, 2015, 05:43:54 PM
Interesting. I wouldnt call 2011 melt season unexceptional though.

I may have to eat crow–tartar because of this early call:

2011 of course is tough competition — the toughest, in fact, in terms of average extent drop during the year — so it's really no surprise 2015 cannot keep up the fight.

but in any case, the gist of it was that 2011 loses more km² in annual average extent during the year than any other in the IJIS time series. 2011 was quite exceptional in that sense, and lost a lot of ice all through the year, preparing the ground for the 2012 record(s).

(I can hear crows now.)
Title: Re: 2015 sea ice area and extent data
Post by: crandles on March 07, 2015, 05:46:02 PM
I was asked about my estimated CT area changes for the next few days. Here we go:

From area calculated from NSIDC sea ice concentration I expect the following changes of  CT-area:

Sun: -13k
Mon: +18k

With those two taking us to 13.034, 27 out of 36 years movements fail to reach a new maximum above 13.275
Title: Re: 2015 sea ice area and extent data
Post by: jdallen on March 07, 2015, 06:19:04 PM

That's what I think the five week running start portends....

A five week running start as of now taking us just past day 100 where temperatures are 15C below freezing

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Focean.dmi.dk%2Farctic%2Fplots%2FmeanTarchive%2FmeanT_2015.png&hash=0d8b9fb4dbdb5645028d5aadebcb05c2)

is nowhere near the same as a 5 week running start as at day 140
That's north of 80, yes? But yes, and I do not expect it to start melt *now*. Most of the extent loss is south of that, and unlike the CAB, is now starting to see sunlight. 

However, I *am* worried the five week lead now WILL translate into a five week running start at day 140.

As I see it, the problem now isn't one of melt starting early, but one of ice failing to freeze late.

I hope that clarifies my concern.
Title: Re: 2015 sea ice area and extent data
Post by: jdallen on March 07, 2015, 06:50:29 PM
Interesting. I wouldnt call 2011 melt season unexceptional though.
Quite so; there was some debate that 2011 actually passed 2007 iirc.  That was proven not true, but definitely a serious melt.
Title: Re: 2015 sea ice area and extent data
Post by: OldLeatherneck on March 07, 2015, 08:31:16 PM
How safe is the current 1M Km2lead over 2012??

Not as safe as many of us may think. I just posted the following on Neven's ASIB.  I'll have further comments following the quote.

Quote
"March MAX Madness"

I can appreciate Neven's reticence in calling the IJIS Extent maximum for 2015. Although many of us, me included, have gotten excited over being 1M Km2 below 2012 at this time, the big question remains as to whether that lead can be maintained until the end of April when insolation becomes a serious player.

While developing my homemade model of sea ice extent decline I've had a chance to seriously look at the detailed IJIS/JAXA data in past years performance. March is one month filled with surprises, with significant up/down fluctuations. This makes predicting the ice extent at the end of April about as foolish as predicting where a hurricane will strike the Atlantic coast the minute a tropical system leave the coast of Africa. Three recent years, 2010, 2012 and 2014 all had extent gains greater than 300K Km2 during the first half of March. In the the last half of March only 2010 had a net gain (139K Km2).

The next week or so will be very interesting to watch!!!

The one nice thing about being retired is that if at any point I am forced to eat crow stew, it won't affect my paycheck. I'll still dabble with projections and occasional prognostication, but I'll save that for the Forum discussions.

Here's my rationale for urging caution at this time.  I spent the most of my career designing experiments, conducting tests, collecting the data, reducing the data, analyzing the data, publishing and at times presenting the results.  To give you some indication of my age, I spent over a dozen years doing these things when all data was collected and plotted using a pencil and a piece of paper.  Imagine how thrilled I was when had access to a Compaq 286 desktop computer and the earliest versions of Lotus 1-2-3.  Now with our access to high speed computers and gigabytes of data automatically processed, we've somehow forgotten to look at what is happening to the raw data. I've had to learn, over the years, not to let my intuitive beforehand knowledge bias how I conduct a test and consequently present the results.

Now getting back the subject at hand.  How safe is the current IJIS Extent 1M Km2 over 2012.  It entirely dependent on what happens during the final weeks of March.  My simplistic  model still shows one scenario that allows 2015's  extent to approach 14M Km2 in late March followed by a gentle decline till ending April above 2012.  The problem with my modelling approach doesn't work well for months like March when the extent can rapidly fluctuate up or down in 100k increments.  If the extent can stay essentially flat-lined for the next two weeks there is a reasonable chance that extent will still be below 2012 at the end of April, however, may not be 1M lower.

Another thing to remember in  the competition to close any year below is how consistently dramatic the monthly losses were during 2012.  After big losses in early March and slightly below average losses in the  last half of march and the first half of April, 2012 went on a rampage.  I'm using semi-monthly bins of data to look at net gains/losses.  From the last half of April through the first half of September, 2012 had record losses 5 times by significant amounts and generally maintained above average losses during most of the other periods.

For the fans of American football, here are my analogies:

1.  A 1M lead in early March is the equivalent of getting a touchdown on the kick-off.....doesn't imply that you will win the game.
2.  A 1M lead in late April is the equivalent of a 2 touchdown lead in the  middle of the 2nd quarter.  You'd be crazy to get too comfrotable about winning.
3.  A 1M lead in mid June is the equivalent of a 3 touchdown lead at the beginning of the 2nd half.  It's getting more possible that you will win....however, it's not so sure that you can get a  second mortgage on your home just to place a large wager on the outcome!!

Title: Re: 2015 sea ice area and extent data
Post by: jdallen on March 07, 2015, 09:00:45 PM
How safe is the current 1M Km2lead over 2012??

Not as safe as many of us may think. I just posted the following on Neven's ASIB.

<snippage>

For the fans of American football, here are my analogies:

1.  A 1M lead in early March is the equivalent of getting a touchdown on the kick-off...
2.  A 1M lead in late April is the equivalent of a 2 touchdown lead ...
3.  A 1M lead in mid June is the equivalent of a 3 touchdown lead ...

Nice Analogy, OLN, and good leavening to our thinking.  I tinkered up numbers, and put together a graph with potential extent based on the current extent, modified by the average 2006-2014 day over day decline.  If born out, it would suggest about a 12-14 day lead in extent loss, once we get to day 140.

For additional contemplation, I found a little insolation calculator (specifically for determining possible utility for PV applications, but works..) and captured raw available KWH/day at specific latitudes over the season. 

The calculator is here: http://pveducation.org/pvcdrom/properties-of-sunlight/calculation-of-solar-insolation (http://pveducation.org/pvcdrom/properties-of-sunlight/calculation-of-solar-insolation)

Images below.

The two week shift could massively increase the energy picked up by the system, by way of reduced albedo.  Now, this will be mostly outside of the central basin - South of 80 - but in normal years, that extra ice would provide a buffer for conditions further north.  We may not have that this year, and by extension, much different and possibly much more unfavorable weather - e.g. more rainfall rather than snowfall over the pack.

More open water also means more heat in that water later in the season when the ice is mobile.  I'd look for anything exported to get more promptly reduced as a result.

[Edit: Michael Hauber correctly points out most of the additional open extent is in the Bering and Okhotsk; that reduces the potential effect on the central basin.  It would be far more worrisome were it on the Atlantic side - where 2015 still lags behind 2012.]
Title: Re: 2015 sea ice area and extent data
Post by: viddaloo on March 07, 2015, 09:58:13 PM
From the last half of April through the first half of September, 2012 had record losses 5 times by significant amounts and generally maintained above average losses during most of the other periods.

For real, 2012 had a total number of 40 'centuries', ie >100,000 km²/day losses. One of them a 'double century', so you could arguably say it had 41. The interesting thing is that 2007 had 27 centuries, which is 2nd highest, and so for these two years, at least, there is a 100% inverse correlation between A) high number of centuries and B) low September minimum.

The other 'forgotten' 2015 fact when people are now virtually queuing up to say a million short is healthy for the pack, is that we had a century loss on Feb 17. Compared to 2007 & 2012 this is one century versus their zero. And although it says nothing about how many we'll have by the end of March, April etc, it is statistically a 'good' sign (if going low is good): 2007 had no century before June, and 2012 had its first on March 8th. If we can keep up with 2012 for the next couple of weeks, it will be very interesting to see, for instance whether a 2015 century number between 27 (2007) and 40 (2012) will land 2015 2nd lowest in September, or at least among the bottom 3.
Title: Re: 2015 sea ice area and extent data
Post by: andy_t_roo on March 07, 2015, 11:18:38 PM
The interesting thing is that 2007 had 27 centuries, which is 2nd highest, and so for these two years, at least, there is a 100% inverse correlation between A) high number of centuries and B) low September minimum.
100% (inverse) correlation implies that all of the change in one of the values predicts all of the change in the other. While correlated, the relationship between count of century drops and overall magnitude of minimum isn't close to '100% inverse'.

Do you know how well this relationship works if extended to the top 10 years in rank?
Title: Re: 2015 sea ice area and extent data
Post by: Jim Hunt on March 08, 2015, 12:02:59 AM
From area calculated from NSIDC sea ice concentration I expect the following changes of  CT-area:

Sun: -13k
Mon: +18k

Which according to my spreadsheet means that CT area will join the ranks of metrics reading lowest for the date since records began.
Title: Re: 2015 sea ice area and extent data
Post by: viddaloo on March 08, 2015, 12:13:10 AM
Code: [Select]
Chart for most centuries:
#1: 2012 (40)
#2: 2007 (27)

Code: [Select]
Chart for lowest yearly minimum:
#1: 2012 (3177455 km²)
#2: 2007 (4065739 km²)

Get it? If you want to split hairs, try finding 3rd and 4th etc years that either fit or don't fit with this 'rule'.

My guess is that if we can get eg:
Code: [Select]
Chart for most centuries:
#1: 2012 (40)
#2: 2015 (32)
#3: 2007 (27)

then we'll also see:

Code: [Select]
Chart for lowest yearly minimum:
#1: 2012 (3177455 km²)
#2: 2015 (something km²)
#3: 2007 (4065739 km²)
Title: Re: 2015 sea ice area and extent data
Post by: OldLeatherneck on March 08, 2015, 01:47:21 PM
Those Pesky, Pesky Details in the Data

While we keep chattering about how unlikely the Feb 15th Max to be exceeded later this month, I decided to look for the Peak Gains between March 7th and March 31st.  When the largest gain in recent history was a gain of over 240K in 2014, I decided to look the details. Last year march 8th & 9th had massive losses which was then followed by a more massive gain of over 432K, peaking on March 20th.

The  remainder of March is bound to have some ups and downs.  If 2015 is going to have a repeat performance of last year, it needs to start soon because after the equinox gains are fewer and much smaller.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi1269.photobucket.com%2Falbums%2Fjj597%2FOldLeatherNeck%2FArctic%2520Ice%2520Ext%25207-31%2520March%25207-31%2520Extreme%2520Gain%2520Plot_zpsmk9px6fr.jpg&hash=9270f17afd99245a153c424aa722b22e)

For the record, here are the only recent years that had gains over 100K between March 7th and March 31st:

Year       Peak Date   Max  Gain
2014       20-Mar           244,288   NOTE: march 9-20 Gain was over 432K
2003       21-Mar           193,833
2013       14-Mar           165,935
2006       10-Mar           138,986
2007       10-Mar           130,667
2004       10-Mar           101,243
Title: Re: 2015 sea ice area and extent data
Post by: Jim Hunt on March 08, 2015, 02:33:24 PM
I went surfing (http://greatwhitecon.info/2015/03/arctic-basin-big-wave-surfing-contest-equipment-evaluation-1/) again yesterday. In not unrelated news this morning:

Arctic Sea Ice Area Lowest Ever (For the Date!) (http://greatwhitecon.info/2015/03/arctic-sea-ice-area-lowest-ever/)
Title: Re: 2015 sea ice area and extent data
Post by: DavidR on March 08, 2015, 03:16:11 PM
I went surfing (http://greatwhitecon.info/2015/03/arctic-basin-big-wave-surfing-contest-equipment-evaluation-1/) again yesterday. In not unrelated news this morning:

Arctic Sea Ice Area Lowest Ever (For the Date!) (http://greatwhitecon.info/2015/03/arctic-sea-ice-area-lowest-ever/)
Not an iceberg in sight! 
Title: Re: 2015 sea ice area and extent data
Post by: Jim Hunt on March 08, 2015, 03:37:58 PM
I went surfing (http://greatwhitecon.info/2015/03/arctic-basin-big-wave-surfing-contest-equipment-evaluation-1/) again yesterday. In not unrelated news this morning:

Arctic Sea Ice Area Lowest Ever (For the Date!) (http://greatwhitecon.info/2015/03/arctic-sea-ice-area-lowest-ever/)
Not an iceberg in sight!

Consequently I was "Toasty in Tiki"!

https://twitter.com/jim_hunt/status/574529991616131072 (https://twitter.com/jim_hunt/status/574529991616131072)

In not unrelated news, Wipneus' earlier prediction has indeed come to pass:

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fgreatwhitecon.info%2Fwp-content%2Fuploads%2F2015%2F03%2FCTArea-2015-Day65.jpg&hash=32d554929639825847f51cada8141115)
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on March 08, 2015, 04:26:59 PM
From area calculated from NSIDC sea ice concentration I expect the following changes of  CT-area:

Sun: -13k
Mon: +18k

Which according to my spreadsheet means that CT area will join the ranks of metrics reading lowest for the date since records began.

Indeed:


CT Area:
13,008,040 km2 (07 March [Day 0.1781])
Down 266,515 km2 (2.01%) from 2015 maximum-to-date of 13,274,555 km2 on 17 February [Day 0.1288].
10,774,031 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Down 20,555 km2 from previous day.
Down 71,071 km2 over past seven days (daily average: -10,153 km2).
Down 71,071 km2 for the month of March (daily average: -10,153 km2).
710,697 km2 below 2000s average for this date.
346,627 km2 below 2010s average for this date.
49,641 km2 below 2014 value for this date.
657,078 km2 below 2012 value for this date.
4th lowest March to-date average.
Lowest value for the date.
1 day this year (1.52% year-to-date) has recorded the lowest daily area.
1 day (1.52%) has recorded the second lowest.
5 days (7.58%) have recorded the third lowest.
7 days in total (10.61%) have been among the lowest three on record.

Title: Re: 2015 sea ice area and extent data
Post by: BornFromTheVoid on March 08, 2015, 05:24:30 PM
Update for the week to March 7th

The current 5 day mean is on 14,315,200km2 while the 1 day extent is at 14,256,200km2.
The daily anomaly (compared to 81-10) is at -1,134,130km2, an increase from -1,023,690km2 last week. The anomaly compared to the 07, 11 and 12 average is at -487,120km2, an increase from -215,650km2 last week. We're currently lowest on record, up from 2nd lowest last week.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2Fo35wUFd.png&hash=c0c2131029eeecc4f6042d2b05d3ab4c)

The average daily change over the last 7 days was -15.3k/day, compared to the long term average of +0.4k/day, and the 07, 11 and 12 average of +20.6k/day.
The average long term change over the next week is +0.7k/day, with the 07, 11, and 12 average being -4.0k/day.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FmSbiboZ.png&hash=70324f2fc8a64f80cf74d11c14bdcf97)

The change so far this March is the 7th most negative on record. To achieve the largest recorded monthly increase, a daily gain of over +22.3k/day is required, while the largest loss requires a loss of at least 25.0k/day and an average requires a loss of -3.6k/day.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2F4ShBUlo.png&hash=02c647a9b6cd5dadfcfa9e863790e79d)
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on March 08, 2015, 05:54:33 PM
From area calculated from NSIDC sea ice concentration I expect the following changes of  CT-area:

Mon: +18k
Tue: -82k
Title: Re: 2015 sea ice area and extent data
Post by: crandles on March 08, 2015, 06:09:37 PM
From area calculated from NSIDC sea ice concentration I expect the following changes of  CT-area:

Mon: +18k
Tue: -82k

Taking us to in the region of 12.944 lower than last 24 or maybe only 23 days. 330k below peak so far.

31 of last 36 year's movements would not reach a new max.
Title: Re: 2015 sea ice area and extent data
Post by: crandles on March 09, 2015, 03:08:31 PM
NSIDC extent 14.18379 lower than all dates in Feb and March so far!

Of last 27 year's movements, only 1 year 2014 results in a new peak at 14.617 which is still a record low.

26/27 is more than 95% but recent years might be more representative, or maybe for such a low point we should look at movements from low points? Therefore not quite ready to say 95% sure we are past peak for NSIDC extent.

95% sure of a record low maximum? Yes I think I will go with that.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on March 09, 2015, 04:01:17 PM
From area calculated from NSIDC sea ice concentration I expect the following changes of  CT-area:

Tue: -82k
Wed: +7k
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on March 10, 2015, 11:59:53 AM
IJIS Extent:
13,629,197 km2 (09 March)
Down 312,863 km2 (2.24%) from 2015 maximum-to-date of 13,942,060 km2 on 15 February.
(NOTE: 2014 increased 432k km2 between this date and its maximum.)
10,451,742 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Down 20,672 km2 from previous day.
Down 168,952 km2 over past seven days (daily average: -24,136 km2).
Down 189,120 km2 for the month of March (daily average: -21,013 km2).
1,031,766 km2 below 2000s average for this date.
588,813 km2 below 2010s average for this date.
386,729 km2 below 2014 value for this date.
888,364 km2 below 2012 value for this date.
Lowest March to-date average.
Lowest value for the date.
14 days this year (20.59% year-to-date) have recorded the lowest daily extent.
11 days (16.18%) have recorded the second lowest.
17 days (25%) have recorded the third lowest.
42 days (61.76%) in total have been among the three lowest on record.


CT Area:
12,968,001 km2 (09 March [Day 0.1836])
Down 306,554 km2 (2.31%) from 2015 maximum-to-date of 13,274,555 km2 on 17 February [Day 0.1288].
(NOTE: 2014 increased 531k km2 between this date and its maximum.)
10,733,992 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Down 68,486 km2 from previous day.
Down 169,022 km2 over past seven days (daily average: -24,146 km2).
Down 111,110 km2 for the month of March (daily average: -12,346 km2).
745,241 km2 below 2000s average for this date.
377,680 km2 below 2010s average for this date.
11,345 km2 above 2014 value for this date.
641,418 km2 below 2012 value for this date.
4th lowest March to-date average.
2nd lowest value for the date.
2 days this year (2.94% year-to-date) have recorded the lowest daily area.
2 days (2.94%) have recorded the second lowest.
5 days (7.35%) have recorded the third lowest.
9 days in total (13.24%) have been among the lowest three on record.
Title: Re: 2015 sea ice area and extent data
Post by: iceman on March 10, 2015, 03:25:29 PM
  ....
26/27 is more than 95% but recent years might be more representative, or maybe for such a low point we should look at movements from low points? Therefore not quite ready to say 95% sure we are past peak for NSIDC extent.
  ....

Agreed that movements from low points (local minima) would have more predictive value.  I'd still place the odds of a later maximum at close to 50%.  That's not statistically based, though, just from eyeballing the forecasts for the coming week.
Title: Re: 2015 sea ice area and extent data
Post by: LRC1962 on March 10, 2015, 03:51:30 PM
Just because I like the cool graphics and do not know its dependability as far as its forcats are concerned.
http://earth.nullschool.net/#current/wind/surface/level/overlay=mean_sea_level_pressure/orthographic=230.93,90.22,651 (http://earth.nullschool.net/#current/wind/surface/level/overlay=mean_sea_level_pressure/orthographic=230.93,90.22,651)
The big low pressure system in the Barents fizzles out in a day or 2, but take a look at at the system south eastern Greenland and see what happens 3 days from now.
http://earth.nullschool.net/#current/wind/surface/level/overlay=mean_sea_level_pressure/orthographic=230.93,90.22,651 (http://earth.nullschool.net/#current/wind/surface/level/overlay=mean_sea_level_pressure/orthographic=230.93,90.22,651)
Doesn't last long but what kind of damage could that do to the faces of the glaciers in that area?
Title: Re: 2015 sea ice area and extent data
Post by: BornFromTheVoid on March 10, 2015, 04:11:53 PM
Latest NSIDC daily extent is the 3rd lowest value on record for March, and lowest for the date by 391k.

With the 5 day trailing average, we're lowest on record by 311k, and 1.24 million below the 81-10 average.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on March 10, 2015, 04:51:31 PM
From area calculated from NSIDC sea ice concentration I expect the following changes of  CT-area:

Wed: +0k (was +7k, NSIDC did update the whole data set since 2015-01-01)
Thu: +18k
Title: Re: 2015 sea ice area and extent data
Post by: crandles on March 10, 2015, 05:20:28 PM
From area calculated from NSIDC sea ice concentration I expect the following changes of  CT-area:

Wed: +0k (was +7k, NSIDC did update the whole data set since 2015-01-01)
Thu: +18k

Actually they have gone back to 1978!
Title: Re: 2015 sea ice area and extent data
Post by: deep octopus on March 10, 2015, 05:24:52 PM
From area calculated from NSIDC sea ice concentration I expect the following changes of  CT-area:

Wed: +0k (was +7k, NSIDC did update the whole data set since 2015-01-01)
Thu: +18k

Actually they have gone back to 1978!

And replaced five decimal places with three. Huh.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on March 10, 2015, 06:01:50 PM
The underlying sea ice concentration data was modified since 2008.

It is odd for NSIDC not to report such changes, last year the announced that the data for a single day in 1984 was changed (http://nsidc.org/the-drift/data-update/erroneous-sea-ice-concentration-data-updated/). Maybe it is work in progress though.
Title: Re: 2015 sea ice area and extent data
Post by: BornFromTheVoid on March 10, 2015, 06:11:09 PM
They did it 2 years ago too for the June data. I send them an email at the time, they said it was related to an updated land mask.
Title: Re: 2015 sea ice area and extent data
Post by: viddaloo on March 10, 2015, 06:43:48 PM
Reminds me of Winston's day–job in Orwell's most widely known novel.
Title: Re: 2015 sea ice area and extent data
Post by: jdallen on March 10, 2015, 07:00:56 PM
  ....
26/27 is more than 95% but recent years might be more representative, or maybe for such a low point we should look at movements from low points? Therefore not quite ready to say 95% sure we are past peak for NSIDC extent.
  ....

Agreed that movements from low points (local minima) would have more predictive value.  I'd still place the odds of a later maximum at close to 50%.  That's not statistically based, though, just from eyeballing the forecasts for the coming week.
I don't see it, Iceman.  I don't think the Arctic can dump the heat being shoved into it from the Atlantic side fast enough.  I don't think the cold snap in the Pacific side will be deep enough, especially with the water temps as high as they are.

The only thing that would give us a new maxima is weather that disperses the pack and reduces concentration.  Even then, it may not significantly increase area.  There's just too much d*mn heat, seems to me...
Title: Re: 2015 sea ice area and extent data
Post by: viddaloo on March 10, 2015, 07:14:05 PM
The only thing that would give us a new maxima is weather that disperses the pack and reduces concentration.  Even then, it may not significantly increase area.  There's just too much d*mn heat, seems to me...

Agree. I'm no expert, but there's a reason 2015 SIE has been down–down–down since Feb 15 and not going up for 22 days. This is no coincidence, and common sense tells me it has to do with heat. We had the record warm ocean and general surface year in 2014, remember? That's a lot of extra heat.
Title: Re: 2015 sea ice area and extent data
Post by: Buddy on March 10, 2015, 08:05:54 PM
What heat...::)

http://climatechangegraphs.blogspot.com/2013/02/sea-surface-temperature-anomaly.html (http://climatechangegraphs.blogspot.com/2013/02/sea-surface-temperature-anomaly.html)

Oh.....THAT heat....

Too much heat in oceans.....and ice will be attacked from all sides come later this spring and through the summer.

It is so hard for "us humans" to wrap our heads around what is...and will be happening now and over the coming months and years.  All of it will be "off the charts" stuff:  Continued melting of the Arctic......continued and serious melting of Greenland....and the continued melting of Antarctica.

Pretty wild stuff ahead of us.....and meanwhile we have to convince a group of "stooges" (OK...we'll call them politicians) that the earth is just BEGINNING to heat up.

Amazing...... Truly f*****g amazing:)

Title: Re: 2015 sea ice area and extent data
Post by: DavidR on March 10, 2015, 11:48:12 PM
The only thing that would give us a new maxima is weather that disperses the pack and reduces concentration.  Even then, it may not significantly increase area.  There's just too much d*mn heat, seems to me...

Agree. I'm no expert, but there's a reason 2015 SIE has been down–down–down since Feb 15 and not going up for 22 days. This is no coincidence, and common sense tells me it has to do with heat. We had the record warm ocean and general surface year in 2014, remember? That's a lot of extra heat.

SIE and SIA have been consistently drifting lower since mid February.  In 2014,  SIE and SIA were consistently moving up until the sudden drop in early  March followed by a return to the trend a week later. In my  view that makes a new Max this year much more unlikely than just  looking at the actual jumps that  occurred in 2014.

According to NSIDC March 9th had the previous highest "lowest extent for the day". On most measures its now downhill to the minimum. Half of the drops, in the last 8  years, taken from the maximum, have the ice second lowest extent on record. All the drops take the ice into the bottom 5.   On those figures Old Leatherneck is giving away money on the blog.

Title: Re: 2015 sea ice area and extent data
Post by: OldLeatherneck on March 11, 2015, 01:45:40 AM

<SNIP>
..........Half of the drops, in the last 8  years, taken from the maximum, have the ice second lowest extent on record. All the drops take the ice into the bottom 5.   On those figures Old Leatherneck is giving away money on the blog.

First of all, I wouldn't risk a thin dime on wagering the outcome of any thing the arctic.   Well, maybe a few pints of beer from time to time.  I was just having fun on the blog.  Although, I did indicate that intuitively I expect 2015, with reasonably good probability, to end up in the lowest 5 years on record.  Secondly, I won't be surprised if 2015 is in fierce competition with 2007, 2011 and 2012 when it comes to July/August and September.  But neither I, nor the the most brilliant meteorologists and climatologists in the world can say with  absolute certainty what the environmental conditions in the Arctic will be like, on a month-to-month basis from April through September.  All we know now is what the weather will probably be like for the next 7-10 days in various regions of the Arctic and the current state of of the ice in those same regions.

Let's wait on our levels of excitement until mid-May when insolation starts to peak for the year.  At that time a massive lead in both area and exent will open a great deal of open water for warming.

Meanwhile, the discussions are informative as well as fun........but can't be put in the bank.
Title: Re: 2015 sea ice area and extent data
Post by: iceman on March 11, 2015, 03:31:54 AM
The only thing that would give us a new maxima is weather that disperses the pack and reduces concentration.  Even then, it may not significantly increase area.  There's just too much d*mn heat, seems to me...

Agree. I'm no expert, but there's a reason 2015 SIE has been down–down–down since Feb 15 and not going up for 22 days. This is no coincidence, and common sense tells me it has to do with heat. We had the record warm ocean and general surface year in 2014, remember? That's a lot of extra heat.

SIE and SIA have been consistently drifting lower since mid February.  In 2014,  SIE and SIA were consistently moving up until the sudden drop in early  March followed by a return to the trend a week later. In my  view that makes a new Max this year much more unlikely than just  looking at the actual jumps that  occurred in 2014.
  ....

All sound reasoning, but land temperatures matter too.  The disfigured jet stream has been pouring arctic air onto northeastern North America for most of the winter.  A big reservoir of cold there, which easterly winds will carry over the Baffin/Newfoundland this week.  Will the coming surge of ice formation be enough to tip the balance toward a later maximum?  Check back on 17th March.
Title: Re: 2015 sea ice area and extent data
Post by: epiphyte on March 11, 2015, 06:58:15 AM

All sound reasoning, but land temperatures matter too.  The disfigured jet stream has been pouring arctic air onto northeastern North America for most of the winter.  A big reservoir of cold there, which easterly winds will carry over the Baffin/Newfoundland this week.  Will the coming surge of ice formation be enough to tip the balance toward a later maximum?  Check back on 17th March.

Well here in Minneapolis it's been consistently much colder than the east coast all winter - but the High/Low temps have gone from 12/-2F six days ago, to 67/37F today... so maybe the cold reservoir isn't as deep as all that!
Title: Re: 2015 sea ice area and extent data
Post by: LRC1962 on March 11, 2015, 10:28:33 AM

All sound reasoning, but land temperatures matter too.  The disfigured jet stream has been pouring arctic air onto northeastern North America for most of the winter.  A big reservoir of cold there, which easterly winds will carry over the Baffin/Newfoundland this week.  Will the coming surge of ice formation be enough to tip the balance toward a later maximum?  Check back on 17th March.
I would not call it a reservoir of cold. For one thing it is bringing the Arctic cold into closer contact with warm tropical air and the temps although cold by local present day standards is no where close to Arctic temps. Although that is not totally true as on several days the North Pole did register temps close to the temps seen in the Northern States.
Title: Re: 2015 sea ice area and extent data
Post by: Rick Aster on March 11, 2015, 06:47:12 PM
I don't think it's a very strong cold band in northeastern North America. If I'm reading the maps right, the cold air hasn't had much success in penetrating the unusually warm air over Hudson Bay.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on March 14, 2015, 06:06:21 PM
From area calculated from NSIDC sea ice concentration I expect the following changes of  CT-area:

(reporting day, change [k], estimated value [M])

Sat       12.994736
Sun -19.6 12.975136
Mon +99.9 13.075036

Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on March 15, 2015, 08:14:44 AM
An in-between update of the NSIDC data changed the number for expected CT area on Monday:

(reporting day, change [k], estimated value [M])
Sat       12.994736
Sun -19.6 12.975136
Mon +37.4 13.012536
Title: Re: 2015 sea ice area and extent data
Post by: BornFromTheVoid on March 15, 2015, 07:24:09 PM
Update for the week to March 14th

The current 5 day mean is on 14,325,800km2 while the 1 day extent is at 14,325,000km2.
The daily anomaly (compared to 81-10) is at -1,172,160km2, an increase from -1,134,130km2 last week. The anomaly compared to the 07, 11 and 12 average is at -462,720km2, a decrease from -487,120km2 last week. We're currently lowest on record, same as last week.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FYW5OgN8.png&hash=43976893f2781cf2f157e29a198d4216)

The average daily change over the last 7 days was +3.5k/day, compared to the long term average of +0.7k/day, and the 07, 11 and 12 average of -4.0k/day.
The average long term change over the next week is -14.1k/day, with the 07, 11, and 12 average being -6.9k/day.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FiHpj50k.png&hash=e23d96672109a0a2f4b602acb2a720be)

The change so far this March is the 7th most negative on record. To achieve the largest recorded monthly increase, a daily gain of over +34.6k/day is required, while the largest loss requires a loss of at least 35.5k/day and an average requires a loss of 3.9k/day.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2Fzc9Vn0Z.png&hash=27e3059c9fc0af25bc2cfb04e6addb6e)
Title: Re: 2015 sea ice area and extent data
Post by: OldLeatherneck on March 16, 2015, 01:05:01 PM
"To Bounce or Not, This is the Question"

Or a better question might be:

Will the current February 15th Maximum stand?  Currently we are 217K Km2 below that level.  Based purely on statistics of previous years gains/losses in the  last 16 days of  March, it would seem likely that the current maximum is safe.  2010 is the only recent year to have a net gain in extent during this period and that gain was only 139K Km2.  However, it can be reasonably assumed that there will be some more upward bumps in the  next few weeks.  It remains to be seen whether these bumps are short lived or a steady succession of massive daily gains.

The chart below is a model that I have developed, using only the statistical data from 2003 to 2014, with the months from March 1st to September 15th broken into 15 or 16 day periods.  I'm plotting 5 projected scenarios from the current date.  The two extreme high/low projections use the record high and low losses for each period respectively.  The remaining three projections use average loss plus 10%, average loss and average loss minus 10%.  The tables below show the data I am using for the remainder of March and the entire month of April.

In no case am I trying to make any absolute predictions as to what will happen in the near future, only what kind of performance relative to previous years historical performance is required to keep 2015's Extent within the range of the previous record years of 2007, 2011 and 2012.

Neither am I using any current weather predictions, nor am I factoring in the current state if the ice in any of the Arctic regions.  I'll let people far smarter and more experienced than I am do that.

At best, my model is a "GUESStimator" rather than a scientific predictor.  However, I have learned a great deal in the process of developing this tool.

March 16-31      
 AVG Loss    206,478   
 MAX Loss    452,018          2014
 MAX Gain   139,124        2010 Note: only year with net gain

April 1-15      
 AVG Loss       526,335   
 MAX Loss    1,080,605    2004
 MIN Loss        278,712     2006

April 16-30      
 AVG Loss      631,407   
 MAX Loss      891,819         2012
 MIN Loss      389,601          2007


(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi1269.photobucket.com%2Falbums%2Fjj597%2FOldLeatherNeck%2FArctic%2520sea%2520ice%2520extent%252015%2520March%25202015%2520Power%2520point_zpscjus4paw.jpg&hash=0c357cca426c48fb3cccb52f25148aa1)
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on March 16, 2015, 01:21:55 PM
IJIS Extent:
13,724,438 km2 (15 March)
Down 217,622 km2 (1.56%) from 2015 maximum-to-date of 13,942,060 km2 on 15 February.
10,546,983 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Up 38,151 km2 from previous day.
Up 74,569 km2 over past seven days (daily average: 10,653 km2).
Down 93,879 km2 for the month of March (daily average: -6,259 km2).
847,381 km2 below 2000s average for this date.
585,865 km2 below 2010s average for this date.
604,754 km2 below 2014 value for this date.
941,873 km2 below 2012 value for this date.
Lowest March to-date average.
Lowest value for the date.
20 days this year (27.03% year-to-date) have recorded the lowest daily extent.
11 days (14.86%) have recorded the second lowest.
17 days (22.97%) have recorded the third lowest.
48 days (64.86%) in total have been among the three lowest on record.


CT Area:
13,001,982 km2 (15 March [Day 0.2000])
Down 272,574 km2 (2.05%) from 2015 maximum-to-date of 13,274,555 km2 on 17 February [Day 0.1288].
10,767,972 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Up 26,192 km2 from previous day.
Down 34,506 km2 over past seven days (daily average: -4,929 km2).
Down 77,129 km2 for the month of March (daily average: -5,142 km2).
617,901 km2 below 2000s average for this date.
394,493 km2 below 2010s average for this date.
442,606 km2 below 2014 value for this date.
442,647 km2 below 2012 value for this date.
2nd lowest March to-date average.
Lowest value for the date.
4 days this year (5.41% year-to-date) have recorded the lowest daily area.
6 days (8.11%) have recorded the second lowest.
5 days (6.76%) have recorded the third lowest.
15 days in total (20.27%) have been among the lowest three on record.
Title: Re: 2015 sea ice area and extent data
Post by: Rubikscube on March 16, 2015, 03:45:50 PM
After a recent dip, the negative anomaly in the sea of Okhotsk is now below 0,5 million square km which means that the previous all time record anomaly in this region has been pulverized. It also appears that the winter max there is going to be lowest ever with a margin of more that 100 000 km^2.
Title: Re: 2015 sea ice area and extent data
Post by: crandles on March 16, 2015, 04:56:58 PM
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Farctic.atmos.uiuc.edu%2Fcryosphere%2FIMAGES%2Fregion.all.anom.region.14.jpg&hash=50c092a10fc2603f8ac06af9b30b7cd4)

2007 anomaly plausible? error?

The record low maximum does appear smashed. Anomaly less clear whether second or first. Either is by large margin.
Title: Re: 2015 sea ice area and extent data
Post by: BornFromTheVoid on March 16, 2015, 05:00:05 PM
Error, without a doubt.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on March 17, 2015, 04:32:22 PM
Weird things are going on in the NSIDC sea ice concentration data. Extent has increased now for two days (+63k and +50k) but area has dropped in no small way. This will be seen in the ct-area numbers tomorrow and the day after, estimated by me as follows:


Mon       13.001982
Tue +6.0 13.007982
Wed -50.9 12.957082
Thu -122.8 12.834282


Epi-center seems to be Hudson Bay region:

Regional Arctic Sea Ice Extent and Area calculated from NSIDC NASA Team concentration data
Date: 2015-03-16 12:00  Values in 1000 km^2  Anomalies are from the 1981-2010 mean values

Extent (value, one day change, anomaly):
   Central Arctic Basin       East Siberian Sea              Laptev Sea
  4456.6   +2.0    +1.7    935.7   +0.0    +0.0    733.9   +0.0    -0.0
               Kara Sea             Barents Sea           Greenland Sea
   899.7   +0.0    +0.9    484.2  -13.8  -351.4    597.6  +20.0  -186.7
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
  1556.2  +17.2  +169.4    287.7   +3.2   +71.5   1230.5   +0.0    -1.8
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
   747.0   +0.0    +0.0    527.6   +0.0    +0.0    602.9   +0.0    +0.0
             Bering Sea          Sea of Okhotsk                   Lakes
   609.8  +17.4  -146.5    579.0   -3.4  -481.4    306.4  -27.0   +76.8
          Other regions       Total (ex. lakes)
    87.7  -20.2  -157.0  14336.0  +22.4 -1081.3

Area (value, one day change, anomaly):
   Central Arctic Basin       East Siberian Sea              Laptev Sea
  4327.6  -37.1   -37.8    931.8   +0.1   +14.2    701.3   -7.9    -9.8
               Kara Sea             Barents Sea           Greenland Sea
   772.6  -31.9   -78.6    280.7  -24.1  -352.8    437.4  +30.0  -128.1
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
  1238.4  +35.7   +96.5    156.7  -12.1   +35.7   1057.0  -68.1  -106.8
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
   703.2   -3.9    -9.5    516.5   -0.8    +6.5    577.1   +3.0    -3.6
             Bering Sea          Sea of Okhotsk                   Lakes
   412.6  +20.4  -111.4    395.8   -4.1  -353.3    216.9  -13.5   +68.8
          Other regions       Total (ex. lakes)
    27.1  -11.1  -104.0  12535.7 -111.7 -1142.7


Title: Re: 2015 sea ice area and extent data
Post by: BornFromTheVoid on March 17, 2015, 04:44:24 PM
I wonder if that might be melt water on the ice, Wipneus? There was that warm spell that set record highs across much of the US, and some very positive anomalies across Hudson Bay in general the last few days.

Title: Re: 2015 sea ice area and extent data
Post by: jdallen on March 17, 2015, 05:00:56 PM
I wonder if that might be melt water on the ice, Wipneus? There was that warm spell that set record highs across much of the US, and some very positive anomalies across Hudson Bay in general the last few days.
Significant anomalies, but oddly, temps are still well below freezing.
Title: Re: 2015 sea ice area and extent data
Post by: LRC1962 on March 17, 2015, 05:09:50 PM
There was a small storm centred around Northern Hudson a few days ago. Could that have shaken things up enough to lower the area, but keep the extent up?
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on March 17, 2015, 06:38:57 PM
I forgot to add that neither Jaxa (bootstrap algorithm) or Uni Hamburg (ASI algorithm) show anything strange in the Hudson.

 The Jaxa thickness/melting maps show some melting in the Hudson.

So all this points at wet ice or wet snow cover, something we normally see at an Arctic scale in June.

Title: Re: 2015 sea ice area and extent data
Post by: Nightvid Cole on March 17, 2015, 07:28:19 PM
Ok, so Okhotsk looks like it won't gain ice. Bering probably won't either - the forecast for (for example) McGrath, AK shows high temps rising above freezing in the coming days which will begin the snowmelt, thus reducing the ice albedo. Baffin/Labrador/St. Lawrence ice covers are already overextended, so little growth expected there either. Where does that leave us? We must have a MASSIVE cold snap in Barents/Kara, REAL SOON, in order to have any chance at threatening the "mad max" on 2/15.
Title: Re: 2015 sea ice area and extent data
Post by: Lord M Vader on March 17, 2015, 08:09:14 PM
Your wish is coming true Mr cole! :P

A cold snap is on the way to Barents/Kara Sea during friday and seems to last for about up to 7 days. This should possibly be able to generate some new ice. If that will be enough to put Mad Max to an end, I don't know. OTOH, it seems like St. Lawrence and the southern part of Labrador Sea will be impacted by two strong cyclones. The question is how much damage they will do to the ice there.

Best, LMV
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on March 18, 2015, 12:04:14 PM
IJIS Extent:
13,720,322 km2 (17 March)
Down 221,738 km2 (1.59%) from 2015 maximum-to-date of 13,942,060 km2 on 15 February.
10,542,867 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Down 35,467 km2 from previous day.
Up 96,554 km2 over past seven days (daily average: 13,793 km2).
Down 97,995 km2 for the month of March (daily average: -5,764 km2).
815,562 km2 below 2000s average for this date.
610,406 km2 below 2010s average for this date.
698,872 km2 below 2014 value for this date.
960,614 km2 below 2012 value for this date.
Lowest March to-date average.
Lowest value for the date.
22 days this year (28.95% year-to-date) have recorded the lowest daily extent.
11 days (14.47%) have recorded the second lowest.
17 days (22.37%) have recorded the third lowest.
50 days (65.79%) in total have been among the three lowest on record.


CT Area:
12,971,601 km2 (17 March [Day 0.2054])
Down 302,955 km2 (2.28%) from 2015 maximum-to-date of 13,274,555 km2 on 17 February [Day 0.1288].
10,737,591 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Down 47,764 km2 from previous day.
Down 8,082 km2 over past seven days (daily average: -1,155 km2).
Down 107,511 km2 for the month of March (daily average: -6,324 km2).
650,471 km2 below 2000s average for this date.
401,583 km2 below 2010s average for this date.
430,720 km2 below 2014 value for this date.
589,372 km2 below 2012 value for this date.
2nd lowest March to-date average.
2nd lowest value for the date.
4 days this year (5.26% year-to-date) have recorded the lowest daily area.
7 days (9.21%) have recorded the second lowest.
6 days (7.89%) have recorded the third lowest.
17 days in total (22.37%) have been among the lowest three on record.
Title: Re: 2015 sea ice area and extent data
Post by: crandles on March 18, 2015, 03:38:25 PM
NSIDC extent

2015,    03,  16,     14.428
2015,    03,  17,     14.298   

- Century break

- 297k below max of 14.595 on 22 Feb

- Movements of last 27 years don't get back up to 14.595

Enough to call the max as 22nd Feb? hmm very cold in Barents is forecast but relatively warm in other critical areas. Very close to callable but I am still not quite going to do so yet.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on March 18, 2015, 04:26:13 PM
From area calculated from NSIDC sea ice concentration I expect the following changes of  CT-area:

Wed       12.971600
Thu -122.8 12.848800
Fri -90.2 12.758601


Feb max is 13.27456, more than half a million above this. The should be enough.
Title: Re: 2015 sea ice area and extent data
Post by: Siffy on March 18, 2015, 04:28:49 PM
From area calculated from NSIDC sea ice concentration I expect the following changes of  CT-area:

Wed       12.971600
Thu -122.8 12.848800
Fri -90.2 12.758601


Feb max is 13.27456, more than half a million above this. The should be enough.

Wow, where do those loses come from is it mostly the hudson?
Title: Re: 2015 sea ice area and extent data
Post by: jdallen on March 18, 2015, 04:43:22 PM
Dang!  Are we falling off a cliff?
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on March 18, 2015, 06:49:59 PM
Wow, where do those loses come from is it mostly the hudson?

Not today. Today it is Kara, Baffin Bay and for extent Barents, Okhotsk  and St. Lawrence regions.

Here is the regional summery for today:

Regional Arctic Sea Ice Extent and Area calculated from NSIDC NASA Team concentration data
Date: 2015-03-17 12:00  Values in 1000 km^2  Anomalies are from the 1981-2010 mean values

Extent (value, one day change, anomaly):
   Central Arctic Basin       East Siberian Sea              Laptev Sea
  4456.6   +0.0    +1.8    935.7   +0.0    +0.0    733.9   +0.0    -0.0
               Kara Sea             Barents Sea           Greenland Sea
   888.8  -10.8    -9.2    452.5  -31.7  -380.8    592.3   -6.0  -197.0
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
  1543.0  -15.1  +160.2    265.8  -21.8   +60.3   1230.5   +0.0    +0.0
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
   747.0   +0.0    +0.0    527.6   +0.0    +0.0    602.9   +0.0    +0.0
             Bering Sea          Sea of Okhotsk                   Lakes
   620.8  +10.5  -137.1    554.3  -24.7  -502.2    315.3   +8.8   +86.7
          Other regions       Total (ex. lakes)
   147.3  -28.7  -143.6  14299.0 -128.4 -1147.5

Area (value, one day change, anomaly):
   Central Arctic Basin       East Siberian Sea              Laptev Sea
  4326.9   -0.4   -39.3    930.3   -1.6   +13.4    691.4   -9.9   -19.9
               Kara Sea             Barents Sea           Greenland Sea
   739.4  -33.2  -112.8    273.4   -7.3  -358.8    440.6   +3.1  -128.8
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
  1210.3  -29.2   +71.4    148.3   -8.4   +34.9   1069.4  +12.4   -93.1
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
   703.7   +0.5    -9.7    510.9   -5.6    +0.2    577.8   +0.6    -2.9
             Bering Sea          Sea of Okhotsk                   Lakes
   432.9  +20.0   -91.1    391.1   -4.7  -352.8    205.5  -11.4   +58.1
          Other regions       Total (ex. lakes)
    43.4   -8.3  -101.2  12489.7  -72.0 -1190.4
Title: Re: 2015 sea ice area and extent data
Post by: jplotinus on March 18, 2015, 07:26:16 PM
Shout out to Viddaloo

Don't gloat. Anything can happen.  :P
Title: Re: 2015 sea ice area and extent data
Post by: viddaloo on March 18, 2015, 08:43:36 PM
What's a gloat?  ::)

Anyway, it seems a lot of people will be eating robin stew over the weekend. I'm hoping they're not extinct or anything in the areas where you guys live? If they are, pop me a PM and I'll send some birds along from Oslo through mail.
Title: Re: 2015 sea ice area and extent data
Post by: ktonine on March 18, 2015, 09:05:15 PM
Robin stew?  What are you talking about - that will land you in jail here.  The robin is the state bird of Wisconsin and as such is protected :)
Title: Re: 2015 sea ice area and extent data
Post by: viddaloo on March 18, 2015, 09:11:44 PM
Robin stew?  What are you talking about - that will land you in jail here.  The robin is the state bird of Wisconsin and as such is protected :)

Guess y'all should have thought about that before, before qualifying to have one.
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on March 18, 2015, 09:42:35 PM
For the record--and please forgive the brief foray intro off-topic territory--"eating crow" is performed by those who predict something to happen that subsequently doesn't; those who out of an abundance of caution chose to make no prediction can happily enjoy a crow-free diet. Thus, if the mid-February maxima do turn out to be this year's icy pinnacles, only someone who claimed those would be definitely surpassed will have to feast on blackbird. And I don't know that anyone did that; I only saw a lot of people being careful.

(And FWIW, I'm still not convinced that either extent, area, or both won't reach new maximums before the melt-out gets underway.)
Title: Re: 2015 sea ice area and extent data
Post by: DavidR on March 18, 2015, 09:55:43 PM
NSIDC extent

2015,    03,  16,     14.428
2015,    03,  17,     14.298   

- Century break

- 297k below max of 14.595 on 22 Feb

- Movements of last 27 years don't get back up to 14.595

Enough to call the max as 22nd Feb? hmm very cold in Barents is forecast but relatively warm in other critical areas. Very close to callable but I am still not quite going to do so yet.
If that figure holds for one day without bouncing back then I  think we can call the max. 

This is just a drop back towards the trend line.  The big late climbs in March all appear to  have occurred after a rapid drop below the trend for that  year.  2014 dropped 250K from trend just  before climbing 500K, 2010 dropped 120K from trend before climbing back 300K.   
Title: Re: 2015 sea ice area and extent data
Post by: jplotinus on March 18, 2015, 10:09:17 PM
The word gloat...
Title: Re: 2015 sea ice area and extent data
Post by: Espen on March 18, 2015, 10:11:39 PM
For the record--and please forgive the brief foray intro off-topic territory--"eating crow" is performed by those who predict something to happen that subsequently doesn't; those who out of an abundance of caution chose to make no prediction can happily enjoy a crow-free diet. Thus, if the mid-February maxima do turn out to be this year's icy pinnacles, only someone who claimed those would be definitely surpassed will have to feast on blackbird. And I don't know that anyone did that; I only saw a lot of people being careful.

(And FWIW, I'm still not convinced that either extent, area, or both won't reach new maximums before the melt-out gets underway.)

I actually did so: https://forum.arctic-sea-ice.net/index.php/topic,230.msg46649.html#msg46649
Title: Re: 2015 sea ice area and extent data
Post by: viddaloo on March 18, 2015, 10:20:56 PM
Espen beat me to it. I waited the 'safe' 22 days before calling it here:

Today also marks the end of the 22–day wait for a new 2015 maximum extent — 22 being the 'safe' wait gleaned from the 2002—2014 IJIS extent time series. No year has ever come back with a higher maximum after 22 days of not beating the previous candidate. I therefore hereby call the 2015 maximum at 13,942,060 km² on Sunday February 15th. We won't see 13.94 million again before February or, perhaps, January 2016.
Title: Re: 2015 sea ice area and extent data
Post by: crandles on March 19, 2015, 12:12:42 AM
If Fri is anywhere near Fri  12.758 then that is 516k below the peak.

The largest rise from that date is 297k following 1992 movements. So there is an extra 200k safety margin over the highest rise of last 36 years. Cold Barents looks slightly concerning but 200k is 60% extra safety margin so I think that should be enough so subject to that 12.758 not being a long way too low, I will call the maximum area to have been that

2015.1288  13.2745552
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on March 19, 2015, 01:08:01 PM
IJIS Extent:
13,708,005 km2 (18 March)
Down 234,055 km2 (1.68%) from 2015 maximum-to-date of 13,942,060 km2 on 15 February.
10,530,550 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Down 12,317 km2 from previous day.
Up 59,725 km2 over past seven days (daily average: 8,532 km2).
Down 110,312 km2 for the month of March (daily average: -6,128 km2).
821,951 km2 below 2000s average for this date.
606,830 km2 below 2010s average for this date.
729,485 km2 below 2014 value for this date.
971,971 km2 below 2012 value for this date.
Lowest March to-date average.
Lowest value for the date.
23 days this year (29.87% year-to-date) have recorded the lowest daily extent.
11 days (14.29%) have recorded the second lowest.
17 days (22.08%) have recorded the third lowest.
51 days (66.23%) in total have been among the three lowest on record.


CT Area:
12,841,934 km2 (18 March [Day 0.2083])
Down 432,621 km2 (3.26%) from 2015 maximum-to-date of 13,274,555 km2 on 17 February [Day 0.1288].
10,607,925 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Down 129,666 km2 from previous day.
Down 142,476 km2 over past seven days (daily average: -20,354 km2).
Down 237,177 km2 for the month of March (daily average: -13,176 km2).
786,679 km2 below 2000s average for this date.
518,889 km2 below 2010s average for this date.
551,827 km2 below 2014 value for this date.
787,511 km2 below 2012 value for this date.
2nd lowest March to-date average.
Lowest value for the date.
5 days this year (6.49% year-to-date) have recorded the lowest daily area.
7 days (9.09%) have recorded the second lowest.
6 days (7.79%) have recorded the third lowest.
18 days in total (23.38%) have been among the lowest three on record.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on March 19, 2015, 06:15:26 PM
From area calculated from NSIDC sea ice concentration I expect the following changes of  CT-area:


Thu       12.841934
Fri -90.2 12.751734
Sat +76.6 12.828334


So the nose dive will not continue for now.  Still 446k below the Feb max  ( 13.27456).
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on March 20, 2015, 01:07:12 PM
IJIS Extent:
13,717,193 km2 (19 March)
Down 224,867 km2 (1.61%) from 2015 maximum-to-date of 13,942,060 km2 on 15 February.
10,539,738 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Up 9,188 km2 from previous day.
Up 21,279 km2 over past seven days (daily average: 3,040 km2).
Down 101,124 km2 for the month of March (daily average: -5,322 km2).
793,369 km2 below 2000s average for this date.
576,739 km2 below 2010s average for this date.
731,106 km2 below 2014 value for this date.
966,893 km2 below 2012 value for this date.
Lowest March to-date average.
Lowest value for the date.
24 days this year (30.77% year-to-date) have recorded the lowest daily extent.
11 days (14.1%) have recorded the second lowest.
17 days (21.79%) have recorded the third lowest.
52 days (66.67%) in total have been among the three lowest on record.


CT Area:
12,753,408 km2 (19 March [Day 0.2109])
Down 521,147 km2 (3.93%) from 2015 maximum-to-date of 13,274,555 km2 on 17 February [Day 0.1288].
10,519,399 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Down 88,526 km2 from previous day.
Down 262,276 km2 over past seven days (daily average: -37,468 km2).
Down 325,703 km2 for the month of March (daily average: -17,142 km2).
895,586 km2 below 2000s average for this date.
558,316 km2 below 2010s average for this date.
616,104 km2 below 2014 value for this date.
729,775 km2 below 2012 value for this date.
2nd lowest March to-date average.
Lowest value for the date.
6 days this year (7.69% year-to-date) have recorded the lowest daily area.
7 days (8.97%) have recorded the second lowest.
6 days (7.69%) have recorded the third lowest.
19 days in total (24.36%) have been among the lowest three on record.

Title: Re: 2015 sea ice area and extent data
Post by: jdallen on March 20, 2015, 05:05:26 PM

CT Area:
12,753,408 km2 (19 March [Day 0.2109])
....
Down 88,526 km2 from previous day.
...
2nd lowest March to-date average.
Lowest value for the date.

These are the numbers I'm most worried about ...
Title: Re: 2015 sea ice area and extent data
Post by: mati on March 20, 2015, 05:27:25 PM
The word gloat...
Schadenfreude (/ˈʃɑːdənfrɔɪdə/; German: [ˈʃaːdn̩ˌfʀɔɪ̯də] ( listen)) is pleasure derived from the misfortunes of others.[1] This word is taken from German and literally means 'harm-joy.' It is the feeling of joy or pleasure when one sees another fail or suffer misfortune. It is also borrowed by some other languages.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on March 22, 2015, 09:47:52 AM
From area calculated from NSIDC sea ice concentration I expect the following changes of  CT-area:

Fr       12.753408
Sa +76.6 12.830008
Su +55.4 12.885408
Mo +44.5 12.929908

Title: Re: 2015 sea ice area and extent data
Post by: Lord M Vader on March 22, 2015, 10:05:41 AM
I expect that if the SIE doesn't see a huge surge during the next 4-5 days I think we could safely call the maximum. This due to a powerful high pressure over western Russia which will push southerlies into the Barents and Kara Sea. After 3-4 days the HP seems to break down but at that point we are almost in April when the sun can start its impact to the ice..

//LMV

Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on March 22, 2015, 01:54:40 PM
From area calculated from NSIDC sea ice concentration I expect the following changes of  CT-area:

Fr       12.753408
Sa +76.6 12.830008
Su +55.4 12.885408
Mo +44.5 12.929908


If that happens--and I have no reason to believe that it won't--it will be the largest three-day area increase since mid-February, and it will knock 2015 out of the bottom three lowest daily measurements for the first time in weeks. However, it will still leave SIA 345k below the 2015 max-to-date, 557k below last year's same-day measurement, and 671k below the same day in 2012.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on March 22, 2015, 04:09:30 PM
There is every reason to doubt future numbers. One thing is that NSIDC revised yesterdays data, which changes the CT prediction for Monday considerably:


Fri       12.753408
Sat +76.6 12.830008
Sun +55.4 12.885408
Mon +9.6 12.895008
Tue -3.0 12.892008

Title: Re: 2015 sea ice area and extent data
Post by: crandles on March 22, 2015, 04:37:31 PM
If we reach 12.892 on Tuesday and then follow 2011 movements, then we will reach 13.2747 above the previous maximum of 13.2746 by all of 0.1k.

But I agree with LMV the weather forecasts do look like the scope for increased area in Barents and Kara does look like it ends in 4 days per forecasts. 382k in 4 days seems quite an ask so I think I am still fairly safe from a crow pie helping.
Title: Re: 2015 sea ice area and extent data
Post by: BornFromTheVoid on March 22, 2015, 06:19:09 PM
Update for the week to March 21st

The current 5 day mean is on 14,341,200km2 while the 1 day extent is at 14,330,000km2.
The daily anomaly (compared to 81-10) is at -1,059,260km2, a decrease from -1,172,160km2 last week. The anomaly compared to the 07, 11 and 12 average is at -422,270km2, a decrease from -462,720km2 last week. We're currently lowest on record, same as last week.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FP7caW3S.png&hash=35288deb9cf4ef618278037e96ed2109)

The average daily change over the last 7 days was +3.3k/day, compared to the long term average of -14.1k/day, and the 07, 11 and 12 average of -6.9k/day.
The average long term change over the next week is -10.3k/day, with the 07, 11, and 12 average being -14.7k/day.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2F64YJdjY.png&hash=570f1cd85cb90c66379ec36a5778222f)

The change so far this March is the 18th most negative on record. To achieve the largest recorded monthly increase, a daily gain of over +54.7k/day is required, while the largest loss requires a loss of at least 61.8k/day and an average requires a loss of 8.1k/day.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FpNZrukL.png&hash=8e543f778728b124f9eb0f55c141f7b6)
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on March 23, 2015, 12:04:39 PM
IJIS Extent:
13,804,766 km2 (22 March)
Down 137,294 km2 (.98%) from 2015 maximum-to-date of 13,942,060 km2 on 15 February.
10,627,311 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Up 66,389 km2 from previous day.
Up 80,328 km2 over past seven days (daily average: 11,475 km2).
Down 13,551 km2 for the month of March (daily average: -616 km2).
653,145 km2 below 2000s average for this date.
422,161 km2 below 2010s average for this date.
520,680 km2 below 2014 value for this date.
776,057 km2 below 2012 value for this date.
Lowest March to-date average.
2nd lowest value for the date.
26 days this year (32.1% year-to-date) have recorded the lowest daily extent.
12 days (14.81%) have recorded the second lowest.
17 days (20.99%) have recorded the third lowest.
55 days (67.9%) in total have been among the three lowest on record.


CT Area:
12,894,189 km2 (22 March [Day 0.2192])
Down 380,366 km2 (2.87%) from 2015 maximum-to-date of 13,274,555 km2 on 17 February [Day 0.1288].
10,660,179 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Up 7,923 km2 from previous day.
Down 107,793 km2 over past seven days (daily average: -15,399 km2).
Down 184,922 km2 for the month of March (daily average: -8,406 km2).
664,506 km2 below 2000s average for this date.
422,322 km2 below 2010s average for this date.
593,148 km2 below 2014 value for this date.
706,362 km2 below 2012 value for this date.
2nd lowest March to-date average.
4th lowest value for the date.
7 days this year (8.64% year-to-date) have recorded the lowest daily area.
8 days (9.88%) have recorded the second lowest.
6 days (7.41%) have recorded the third lowest.
21 days in total (25.93%) have been among the lowest three on record.

Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on March 23, 2015, 06:49:15 PM

Fri       12.753408
Sat +76.6 12.830008
Sun +55.4 12.885408
Mon +9.6 12.895008
Tue -3.0 12.892008


Monday CT released a value 12.894189. I have made worse predictions than that.

With NSIDC's sea ice concentration from today, I expect the following changes of  CT-area:


Mon       12.894189
Tue -3.0 12.891189
Wed +65.7 12.956889


Still about 320k below the 2015 max.

Title: Re: 2015 sea ice area and extent data
Post by: crandles on March 24, 2015, 03:37:19 PM
NSIDC
2015,    03,  21,     14.331
2015,    03,  22,     14.457
2015,    03,  23,     14.508

now within 87k of max this year.

Gain in last two days is 178k that is a rate of +89k per day. By friday morning it is warming up in Barents, but there is still Tuesday's and Wednesday's data even if Thursday's reading might break an upward trend.

JAXA has more extent than last 23 days but the chances of this or the current close proximity to this year maximum having any effect on Viddaloo calling his method for calling the maximum 'verified' is left as an exercise for the imagination.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on March 24, 2015, 04:14:47 PM
With NSIDC's sea ice concentration from today, I expect the following changes of  CT-area:


Tue       12.898746
Wed +65.7 12.964446
Thu +66.5 13.030945


Prelim? max 2015 is still 13.273 Mm2
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on March 25, 2015, 09:28:46 AM
In the past few years I have been trying to get behind the detailed calculation of Cryosphere Today's area calculation.  To summarize my findings:

 (CT area short for calculation of Cryosphere Today area)

- CT area is based on NSIDC near real time sea ice concentration data. Whenever NSIDC updates this data, CT area is not;
- CT area lags the release of the NSIDC data by two days;
- CT area includes all ice, including lake ice;
- CT area used a fixed grid size of 625 km2 (over estimating low latitude ice and underestimating ice near the pole);

The replicated area is quite near the real value, but not exact. Day to day changes as reported here often differ by 10-20k, sometimes more than that.
Now thanks to the perseverance of Michael Yorke,  who was not satisfied with these results and questioned about everything about my calculations a next step can be made in perfect replication of the Cryosphere Today area numbers (including SH and global numbers).

This finding is:

-CT area does NOT uses a 15% cutoff. In fact no cutoff is applied and all sea ice is counted;

This was a bit of a surprise to me, an have to think a bit about the consequences.

Is this final? Perhaps not, there are still questions about how the ice area in the pole hole is calculated and how missing data is handled. The pole hole has recently been decimated and is included in the CT area calculations from about March 9.

In all I expect that my two day estimate will improve considerable by this, perhaps by a factor of 10.

We can observe this from now on. For the two next updates I expect (changes in 1000 km2):


Tue       12.898746
Wed +51.6 12.950333
Thu +81.5 13.031828

Title: Re: 2015 sea ice area and extent data
Post by: Neven on March 25, 2015, 10:38:03 AM
Is this final? Perhaps not, there are still questions about how the ice area in the pole hole is calculated and how missing data is handled. The pole hole has recently been decimated and is included in the CT area calculations from about March 9.
Wip, back in 2010 when there was a lot of open water near the Pole (or as I called it the North Hole (http://neven1.typepad.com/blog/2010/09/north-hole.html)), I asked someone from CT about how they handled it, and this was their reply:

In our area timeseries, we fill in the hole with an average value. The value is obtained by taking the average concentration value over all longitudes for the degree latitude circle surrounding the hole. The size of the hole changes with each sensor/platform, but if the hole is 87 deg. N to the pole, for example, we average all available concentrations in the circle 86 deg. N to 87 deg. N and fill in all points in the hole with that value.

I don't know if they still do it that way.
Title: Re: 2015 sea ice area and extent data
Post by: Neven on March 25, 2015, 10:38:19 AM
JAXA has reported a small drop of 1478 km2, the difference is still 108K km2, and given the change in forecast (higher temps and changing winds in the Barentsz Sea) I think this is it. Barring a 100K+ change being reported tomorrow, of course. :-)
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on March 25, 2015, 10:47:52 AM
Is this final? Perhaps not, there are still questions about how the ice area in the pole hole is calculated and how missing data is handled. The pole hole has recently been decimated and is included in the CT area calculations from about March 9.
Wip, back in 2010 when there was a lot of open water near the Pole (or as I called it the North Hole (http://neven1.typepad.com/blog/2010/09/north-hole.html)), I asked someone from CT about how they handled it, and this was their reply:

In our area timeseries, we fill in the hole with an average value. The value is obtained by taking the average concentration value over all longitudes for the degree latitude circle surrounding the hole. The size of the hole changes with each sensor/platform, but if the hole is 87 deg. N to the pole, for example, we average all available concentrations in the circle 86 deg. N to 87 deg. N and fill in all points in the hole with that value.

I don't know if they still do it that way.

Thanks, that is almost the same what I do. The difference is that I don't calculate in degrees but in pixels ( grid cells if you want to). I take a "ring" two pixels wide to calculate average concentration and use that for the interior of the hole.
With a pole hole of only 44 pixels in total, down from 468, you cannot make big errors there anymore.
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on March 25, 2015, 11:34:59 AM
IJIS Extent:
13,833,407 km2 (24 March)
Down 108,653 km2 (.78%) from 2015 maximum-to-date of 13,942,060 km2 on 15 February.
10,655,952 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Down 1,478 km2 from previous day.
Up 113,085 km2 over past seven days (daily average: 16,155 km2).
Up 15,090 km2 for the month of March (daily average: 629 km2).
618,870 km2 below 2000s average for this date.
353,610 km2 below 2010s average for this date.
246,531 km2 below 2014 value for this date.
678,320 km2 below 2012 value for this date.
Lowest March to-date average.
2nd lowest value for the date.
26 days this year (31.33% year-to-date) have recorded the lowest daily extent.
14 days (16.87%) have recorded the second lowest.
17 days (20.48%) have recorded the third lowest.
57 days (68.67%) in total have been among the three lowest on record.


CT Area:
12,950,359 km2 (24 March [Day 0.2246])
Down 324,196 km2 (2.44%) from 2015 maximum-to-date of 13,274,555 km2 on 17 February [Day 0.1288].
10,716,350 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Up 51,614 km2 from previous day.
Down 21,241 km2 over past seven days (daily average: -3,034 km2).
Down 128,752 km2 for the month of March (daily average: -5,365 km2).
556,525 km2 below 2000s average for this date.
325,110 km2 below 2010s average for this date.
373,227 km2 below 2014 value for this date.
625,440 km2 below 2012 value for this date.
2nd lowest March to-date average.
4th lowest value for the date.
7 days this year (8.43% year-to-date) have recorded the lowest daily area.
8 days (9.64%) have recorded the second lowest.
6 days (7.23%) have recorded the third lowest.
21 days in total (25.3%) have been among the lowest three on record.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on March 25, 2015, 02:36:17 PM
The prediction was:

Quote
Wed +51.6 12.950333

Actual:

12.95036 (+51.6)
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on March 25, 2015, 03:08:09 PM
The prediction was:

Quote
Wed +51.6 12.950333

Actual:

12.95036 (+51.6)

Yep. Nailed it...
Title: Re: 2015 sea ice area and extent data
Post by: crandles on March 25, 2015, 03:17:00 PM
Very impressive 5 9s accuracy  :)

Unlike my NSIDC prognostications  :( , down 138k today to 14.368; that is now 227k below peak. 227k isn't a huge amount but the weather in the coming week is going to warm Barents sea and then time has just about run out for a late max.

Since I was so wrong about timing of this last peak, I am going to shut up rather than calling the maximum.
Title: Re: 2015 sea ice area and extent data
Post by: viddaloo on March 25, 2015, 03:20:03 PM
Just wondering, has the term 'sea ice maximum denier' been used before in this forum, or am I the first to use it right here?
Title: Re: 2015 sea ice area and extent data
Post by: crandles on March 25, 2015, 03:44:01 PM
If I am not calling it, I can still be thinking it is very highly likely that it has already happened.

I said you were probably going to be right when you first called the maximum (but also that your method was suspect not giving sufficient certainty before calling it).

Thinking it is very highly likely that the 2015 maximum has happened in the past makes me a (sea ice maximum) denier does it?  ;D
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on March 25, 2015, 04:11:30 PM
With NSIDC's sea ice concentration from today, I expect the following changes of  Cryosphere Today area:

Wed       12.950359
Thu +81.5 13.031854
Fri -16.1 13.015730

Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on March 25, 2015, 08:39:02 PM
Just wondering, has the term 'sea ice maximum denier' been used before in this forum, or am I the first to use it right here?

Seriously? You're equating being cautious about calling the Arctic sea ice maximum with refusal to acknowledge the reality of--and overwhelming evidence for--climate change?

Again: seriously?

Watching the ice melt is, for most of us, an interesting hobby. That's why many of us are here. But a lot of the fun gets sucked out of that hobby when a fellow participant resorts to berating, ridiculing, and name calling those who simply disagree with him. With that in mind, do you think you could maybe tone down the rhetoric just a bit? All of us are aware that polar ice is rapidly disappearing; no intelligent and sane person is in denial of that. But, as has been stated here too many times to mention, an early maximum is no more an indicator of a lower minimum than a late maximum ensures a high minimum. So those of us waiting to see whether extent exceeds its maximum-to-date aren't refusing to admit the ice is disappearing; we're just using wisdom and common sense to avoid looking foolish. So, you know, stop. Please.

Thanks...
Title: Re: 2015 sea ice area and extent data
Post by: viddaloo on March 25, 2015, 08:58:08 PM
That rant was over the top, Jim. I know many people think a word means what that word makes them feel it means, but a denier of a sea ice maximum has absolutely nothing to do with denying manmade global warming, or indeed any other stuff you can deny. There's been a lot of talk about "eating crow" here, and that's fun. That's what this is too. Only a bit of fun. For what it's worth, the long plateau of uncertainty has brought along a new hypothesis about why it is that long and wide, and what the length of this plateau may indicate for the rest of the melt season. You may want to look at my post (http://forum.arctic-sea-ice.net/index.php/topic,1149.msg48648.html#msg48648) about this, building on DavidR's work, if you're in that serious mood.
Title: Re: 2015 sea ice area and extent data
Post by: Neven on March 25, 2015, 09:20:39 PM
I take offence at the term 'denier'. Call me a 'sea ice maximum skeptic'.  ;) ;D
Title: Re: 2015 sea ice area and extent data
Post by: Lord M Vader on March 25, 2015, 09:31:43 PM
Neven: I think the term "careful and experienced general" is a better term to describe someone who doesn't call a maximum until there is absolutely 100% certain :)

Have a good day General Neven! :)

Best, LMV
Title: Re: 2015 sea ice area and extent data
Post by: viddaloo on March 25, 2015, 09:34:10 PM
Neven, I'm glad you and others take it for what it is: A joke, or more accurate; teasing. And I agree a skeptic is better to be than a denier. ;)

Now, I may have stated that my 22–day algorithm for calling the maximum was 'verified' the other week, following official agencies half–calling it. It is of course not properly verified before we're in even more safe territory, say, below 13 million. But one also needs to remember that 'verified' does not mean absolutely true. In science it means sustained for the time being, or 'not yet falsified'.

With the current trend of longer and longer plateaus, I have no doubt the algorithm will be falsified before the end of this decade, if length is related to ocean heat content. But on the other hand, then the max would no longer be that interesting, and length would be the topic of discussion.
Title: Re: 2015 sea ice area and extent data
Post by: DavidR on March 25, 2015, 10:32:17 PM
Very impressive 5 9s accuracy  :)

Unlike my NSIDC prognostications  :( , down 138k today to 14.368; that is now 227k below peak. 227k isn't a huge amount but the weather in the coming week is going to warm Barents sea and then time has just about run out for a late max.

Since I was so wrong about timing of this last peak, I am going to shut up rather than calling the maximum.
The NSIDC 5 day average is now 132 K below the peak and with todays fall it will need a sustained rise for about a week to have any chance of getting above that point. 2010 achieved 175K rise from todays date so it is still possible. The six day rise before that peak was 233 K so just enough to beat this years single day peak.

Having said that the weather prediction for the rest of the week suggests a significant drop for the 5  day average with an unheard of rise being required to return to the peaks after that.

In my view both the current maximums are now completely out of reach.

Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on March 26, 2015, 12:08:10 PM
Whoever registered to the free Jaxa's GCOM-W1 (which carries the AMSR2 instrument) data services received this:

Quote
This is the help desk of the GCOM-W1 Data Providing Service.

We are pleased to announce the release of the new version of AMSR2 all
products on March 26, 2015.

The revised version is changed as follow;

?Ver2.0?2.200.200?

For the details, please refer to the following page:

  The new version of AMSR2 all products have been released.
?<http://gcom-w1.jaxa.jp/contents/150326_Ver2.0_release_e.pdf>

Regarding the product observed before Mar 25, 2015, JAXA is going to
reprocess and provide them in sequence.

When JAXA duly releases the new version of AMSR2 product, JAXA is going
to update detail information on website (GCOM-W1 Data Providing Service).

If you have any questions regarding the AMSR2 products or this website,
please contact our Help Desk as customer service.
Please feel free to ask if there is anything about which you are uncertain.

We hope that you will actively use our website for the years to come.

Sincerely yours,

Help Desk / GCOM-W1 Data Providing Service

For Sea Ice Concentration this seems applicable:

Quote
Sea Ice Concentration (SIC)
Reduction of pseudo sea ice areas.


I guess they mean false ice due to storms, vapor and liquid water in clouds, which does affect Jaxa's sea ice concentration product.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on March 26, 2015, 04:17:43 PM
With NSIDC's sea ice concentration from today, I expect the following changes of  CT-area:

Thu       13.031122
Fri -16.1 13.014998
Sat +77.0 13.092025


Today's forecast was:
Quote
Thu +81.5 13.031854
Final value:
13.031122 (+80.8)


Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on March 27, 2015, 12:27:33 PM
IJIS Extent:
13,883,904 km2 (26 March)
Down 58,156 km2 (0.42%) from 2015 maximum-to-date of 13,942,060 km2 on 15 February.
10,706,449 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Up 29,525 km2 from previous day.
Up 166,711 km2 over past seven days (daily average: 23,816 km2).
Up 65,587 km2 for the month of March (daily average: 2,523 km2).
546,701 km2 below 2000s average for this date.
315,042 km2 below 2010s average for this date.
165,911 km2 below 2014 value for this date.
563,074 km2 below 2012 value for this date.
Lowest March to-date average.
3rd lowest value for the date.
26 days this year (30.59% year-to-date) have recorded the lowest daily extent.
15 days (17.65%) have recorded the second lowest.
18 days (21.18%) have recorded the third lowest.
59 days (69.41%) in total have been among the three lowest on record.


CT Area:
13,031,122 km2 (25 March [Day 0.2274])
Down 243,433 km2 (1.83%) from 2015 maximum-to-date of 13,274,555 km2 on 17 February [Day 0.1288].
10,797,113 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Up 80,763 km2 from previous day. [NOTE: largest single-day increase since max-to-date]
Up 189,188 km2 over past seven days (daily average: 27,027 km2).
Down 47,989 km2 for the month of March (daily average: -1,920 km2).
460,382 km2 below 2000s average for this date.
247,530 km2 below 2010s average for this date.
230,453 km2 below 2014 value for this date.
514,597 km2 below 2012 value for this date.
2nd lowest March to-date average.
4th lowest value for the date.
7 days this year (8.33% year-to-date) have recorded the lowest daily area.
8 days (9.52%) have recorded the second lowest.
6 days (7.14%) have recorded the third lowest.
21 days in total (25%) have been among the lowest three on record.



Title: Re: 2015 sea ice area and extent data
Post by: Siffy on March 27, 2015, 01:03:24 PM
Looks like IJIS extent is going to breach the maximum on Saturday if Wipneus figures hold up. That would make it the latest maximum for extent?
Title: Re: 2015 sea ice area and extent data
Post by: RaenorShine on March 27, 2015, 01:10:55 PM
Looks like IJIS extent is going to breach the maximum on Saturday if Wipneus figures hold up. That would make it the latest maximum for extent?

Wipneus's Figures refer to CT area which reports 3 days in arrears.  He estimates the change by analysing the base data from NSIDC from which the data is derived.

IJIS figures are only a day in arrears so is not related.  From comments by Neven (and others) I'm expecting IJIS to start falling soon, so a near miss as far as a late maximum is concerned.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on March 27, 2015, 01:19:07 PM
Looks like IJIS extent is going to breach the maximum on Saturday if Wipneus figures hold up. That would make it the latest maximum for extent?

No, the reason that I can "predict" CT area is that CT data are delayed. Or in an other way: today's CT number is based on the NSIDC ice concentration data that was first released two days ago.

So my "prediction" does not have to say anything about Jaxa extent (formerly known as IJIS extent), NSIDC sea ice index, and a number of other sources of extent (including my "home brew" calculations).
Title: Re: 2015 sea ice area and extent data
Post by: Siffy on March 27, 2015, 01:19:52 PM
Looks like IJIS extent is going to breach the maximum on Saturday if Wipneus figures hold up. That would make it the latest maximum for extent?

No, the reason that I can "predict" CT area is that CT data are delayed. Or in an other way: today's CT number is based on the NSIDC ice concentration data that was first released two days ago.

So my "prediction" does not have to say anything about Jaxa extent (formerly known as IJIS extent), NSIDC sea ice index, and a number of other sources of extent (including my "home brew" calculations).

Opps, my apologies.

 :-[

Title: Re: 2015 sea ice area and extent data
Post by: DavidR on March 27, 2015, 02:05:01 PM
Looks like IJIS extent is going to breach the maximum on Saturday if Wipneus figures hold up. That would make it the latest maximum for extent?

No, the reason that I can "predict" CT area is that CT data are delayed. Or in an other way: today's CT number is based on the NSIDC ice concentration data that was first released two days ago.

So my "prediction" does not have to say anything about Jaxa extent (formerly known as IJIS extent), NSIDC sea ice index, and a number of other sources of extent (including my "home brew" calculations).
However the rise in area takes CT area within 200K of the 5 day average maximum, extending my plateau hypothesis by another 10 days and driving my  projection for the minimum to within 190 K km^2 of the 2012 record minimum.
Title: Re: 2015 sea ice area and extent data
Post by: viddaloo on March 27, 2015, 04:40:41 PM
I take offence at the term 'denier'. Call me a 'sea ice maximum skeptic'.  ;) ;D

Sometimes, being a skeptic is the only rational option. In particular, I'd say, in matters related to the Arctic. For instance, I have no doubt we'll crush the Feb 15 maximum if we stay on the plateau for another week. In general, it's just a matter of time if the length of the plateau pushes 40 or 50 days, then it's all down to chance. However, there is a trend towards jumping off the plateau earlier in the year for lower plateaus. If we can jump off it now, the early Mad Max will be safe, IMO.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on March 27, 2015, 06:21:27 PM
With NSIDC's sea ice concentration from today, I expect the following changes of  CT-area:

Thu       13.031122
Fri -16.1 13.014998
Sat +77.0 13.092025
Sun -20.3 13.071745

Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on March 28, 2015, 03:10:32 PM
Obscure stat of the day: the current multi-day increase in CT SIA of 340k km2 is the largest pre-minimum 8-day growing period in the satellite record to commence so late in the year.

SIA is now just 181k short of the max-to-date on 17 February.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on March 28, 2015, 04:34:10 PM
With NSIDC's sea ice concentration from today, I expect the following changes of  CT-area:

Sat       13.093628
Sun -20.3 13.073348
Mon -79.6 12.993729


Today's prediction was:
Quote
Sat +77.0 13.092025

Actual:
13.093628 (+77.5k)
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on March 29, 2015, 04:18:36 PM
With NSIDC's sea ice concentration from today, I expect the following changes of  CT-area:

Sat       13.093628
Sun -20.3 13.073348
Mon -79.6 12.993729
Tue -38.1 12.955638

Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on March 30, 2015, 01:12:09 PM
IJIS Extent:
13,724,252 km2 (29 March)
Down 217,808 km2 (1.56%) from 2015 maximum of 13,942,060 km2 on 15 February.
10,546,797 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Down 51,716 km2 from previous day.
Down 80,514 km2 over past seven days (daily average: -11,502 km2).
Down  94,065 km2 for the month of March (daily average: 3,204 km2).
611,085 km2 below 2000s average for this date.
423,337 km2 below 2010s average for this date.
130,761 km2 below 2014 value for this date.
812,126 km2 below 2012 value for this date.
Lowest March to-date average.
2nd lowest value for the date.
26 days this year (29.55% year-to-date) have recorded the lowest daily extent.
17 days (19.32%) have recorded the second lowest.
19 days (21.59%) have recorded the third lowest.
62 days (70.45%) in total have been among the three lowest on record.


CT Area:
12,993,255 km2 (29 March [Day 0.2384])
Down 281,301 km2 (2.12%) from 2015 maximum of 13,274,555 km2 on 17 February [Day 0.1288].
10,759,245 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Down 79,753 km2 from previous day.
Up 99,066 km2 over past seven days (daily average: 14,152 km2).
Down 85,856 km2 for the month of March (daily average: -2,961 km2).
429,574 km2 below 2000s average for this date.
347,304 km2 below 2010s average for this date.
358,458 km2 below 2014 value for this date.
643,447 km2 below 2012 value for this date.
3rd lowest March to-date average.
4th lowest value for the date.
7 days this year (7.95% year-to-date) have recorded the lowest daily area.
8 days (9.09%) have recorded the second lowest.
6 days (6.82%) have recorded the third lowest.
21 days in total (23.86%) have been among the lowest three on record.

Title: Re: 2015 sea ice area and extent data
Post by: Stephen on March 31, 2015, 12:04:20 AM
With NSIDC's sea ice concentration from today, I expect the following changes of  CT-area:

Sat       13.093628
Sun -20.3 13.073348
Mon -79.6 12.993729


Today's prediction was:
Quote
Sat +77.0 13.092025

Actual:
13.093628 (+77.5k)

Who da man?  YOU da man!

Seriously, I really appreciate your work.
Title: Re: 2015 sea ice area and extent data
Post by: Neven on March 31, 2015, 12:07:20 AM
Yes, Wip, looks like you solved the riddle, except for a couple of hundreds km2. Well done.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on March 31, 2015, 08:21:20 AM
Yes, Wip, looks like you solved the riddle, except for a couple of hundreds km2. Well done.

Handling of the missing data seems to be the major source of difference now. I am filling the gaps in with older data. Michael gets better results with an average of older and newer data. Great, but not so suitable for making those predictions (when those newer data do not exist yet).

The sea ice concentration in the pole hole is now close to 100%, the accuracy of the estimate will become more important later in the season. 
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on March 31, 2015, 08:32:05 AM
Got this from the GCOM-W1 (the satellite which carries the AMSR2 instrument) data providing help desk.

Quote
To all registered users of GCOM-W1 Data Providing Service:

This is the help desk of the GCOM-W1 Data Providing Service.

We are temporarily stopping provision of the following products.

  ・L2 Sea Ice Concentration (SIC)
  ・L3 all products

When we resume the provision, we will notify you about it again.

We apologize for any inconvenience this may have caused you.

If you have any question, please do not hesitate to ask us.

Sincerely yours,

Help Desk / GCOM-W1 Data Providing Service

L3 sea ice concentration is what I use for the regional Jaxa extent and area calculation. So that is stopped as well.
The L2 images where posted in the forum as well, they where the among the earliest indications of sea ice concentration developments available.

Since the Jaxa extent (formerly known as IJIS extent) still continues to be released, sea ice concentration data must still be produced. Not for us unfortunately.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on March 31, 2015, 04:11:04 PM
With NSIDC's sea ice concentration from today, I expect the following changes of  CT-area:

Tue       12.954735
Wed +35.8 12.990537
Thu -2.1 12.988480


Wed +35.6 12.990381
Thu -1.8 12.988534


Predicted for today was:
Quote
Tue -38.1 12.955638

Reality:
Tue -38.5 12.954735


[EDIT 2015/4/1 : implemented filling in missing data with the average of previous and following days]
Title: Re: 2015 sea ice area and extent data
Post by: BornFromTheVoid on March 31, 2015, 05:58:51 PM
Update for the week to March 28th

The current 5 day mean is on 14,421,200km2 while the 1 day extent is at 14,351,000km2.
The daily anomaly (compared to 81-10) is at -907,130km2, a decrease from -1,059,260km2 last week. The anomaly compared to the 07, 11 and 12 average is at -239,070km2, a decrease from -422,270km2 last week. We're currently 3rd lowest on record, down from lowest on record last week.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2Fon4UIPh.png&hash=79dfaf81dc3ff0504386defbcae280f9)

The average daily change over the last 7 days was +11.4k/day, compared to the long term average of -10.3k/day, and the 07, 11 and 12 average of -14.7k/day.
The average long term change over the next week is -22.9k/day, with the 07, 11, and 12 average being -7.3k/day.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FmribOzW.png&hash=1028353583e89c080c4f673ff56e3679)

The change so far this March is the 11th least negative on record. To achieve the largest recorded monthly increase, a daily gain of over +155.5k/day is required, while the largest loss requires a loss of at least 232.7k/day and an average requires a loss of 53.7k/day.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FOzZ0HU0.png&hash=d40bad397bafc9e1516a5200b6a40076)
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on April 01, 2015, 12:53:22 PM
IJIS Extent:
13,665,311 km2 (31 March)
Down 276,749 km2 (1.98%) from 2015 maximum-to-date of 13,942,060 km2 on 15 February.
10,487,856 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Down 29,829 km2 from previous day.
Down 168,096 km2 over past seven days (daily average: -24,014 km2).
Down 153,006 km2 for the month of March (daily average: -4,936 km2).
608,479 km2 below 2000s average for this date.
493,411 km2 below 2010s average for this date.
211,863 km2 below 2014 value for this date.
865,496 km2 below 2012 value for this date.
Lowest March average on record.
2nd lowest value for the date.
26 days this year (28.89% year-to-date) have recorded the lowest daily extent.
19 days (21.11%) have recorded the second lowest.
19 days (21.11%) have recorded the third lowest.
64 days (71.11%) in total have been among the three lowest on record.


CT Area:
12,990,146 km2 (31 March [Day 0.2439])
Down 284,410 km2 (2.14%) from 2015 maximum-to-date of 13,274,555 km2 on 17 February [Day 0.1288].
10,756,136 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Up 35,411 km2 from previous day.
Up 39,786 km2 over past seven days (daily average: 5,684 km2).
Down 88,965 km2 for the month of March (daily average: -2,870 km2).
399,930 km2 below 2000s average for this date.
330,484 km2 below 2010s average for this date.
118,359 km2 below 2014 value for this date.
716,258 km2 below 2012 value for this date.
3rd lowest March average on record.
4th lowest value for the date.
7 days this year (7.78% year-to-date) have recorded the lowest daily area.
8 days (8.89%) have recorded the second lowest.
6 days (6.67%) have recorded the third lowest.
21 days in total (23.33%) have been among the lowest three on record.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on April 01, 2015, 05:07:48 PM
With NSIDC's sea ice concentration from today, I expect the following changes of  CT-area:

Wed       12.990146
Thu -0.9 12.989282
Fri +3.3 12.992571

Today was supposed to:
Quote
Wed +35.6 12.990381
But instead:
Wed +35.4 12.990146
Title: Re: 2015 sea ice area and extent data
Post by: epiphyte on April 01, 2015, 06:27:43 PM
Did you forget to subtract Superman's fortress of solitude? It's an easy one to miss...
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on April 03, 2015, 08:35:17 AM
Bringing out a new release and within a few days forced to announce another one is a nightmare. Happened to Jaxa GCOM-W1 data service:

Quote
This is the help desk of the GCOM-W1 Data Providing Service.

After the AMSR2 product updates (Version 2.0) on March 26, 2015,
we have found inadequate parameter settings in the Level (L)-1
processing system.
To solve these issues, we are going to release all the updated Version
2.1 AMSR2 product (L1, L2, and L3)
again on April 3, 2015.

We apologize to all AMSR2 data users for this inconvenience.

For those who already acquired the Version 2.0 products,
we strongly recommend to download Version 2.1 products and replace older
versions with them.

Major product changes associated with this update are as follows.

  Release of updated AMSR2 products (Version 2.1)
?<http://gcom-w1.jaxa.jp/contents/150403_Ver2.1_release_e.pdf>

If you have any questions regarding the AMSR2 products or this website,
please contact our Help Desk as customer service.
Please feel free to ask if there is anything about which you are uncertain.

We hope that you will actively use our website for the years to come.

Sincerely yours,

Help Desk / GCOM-W1 Data Providing Service


This does influence the reliability of my "home brew" data and probably also the Jaxa extent data (formerly known as IJIS extent data) of the last few days.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on April 03, 2015, 08:46:09 AM
With the latest NSIDC's sea ice concentration , I expect the following changes of  CT-area:



Thu       12.990585
Fri +3.2 12.993751
Sat -11.7 12.982079


predicted for Thursday:
Quote
Thu -0.9 12.989282
actual:
Thu  +0.4  12.990585
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on April 03, 2015, 02:10:32 PM
IJIS Extent:
13,610,885 km2 (02 April)
Down 331,175 km2 (2.38%) from 2015 maximum-to-date of 13,942,060 km2 on 15 February.
10,433,430 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Down 36,770 km2 from previous day.
Down 273,019 km2 over past seven days (daily average: -39,003 km2).
Down 54,426 km2 for the month of April (daily average: -27,213 km2).
606,131 km2 below 2000s average for this date.
508,284 km2 below 2010s average for this date.
246,607 km2 below 2014 value for this date.
862,912 km2 below 2012 value for this date.
2nd lowest April to-date average.
Lowest value for the date.
27 days this year (29.35% year-to-date) have recorded the lowest daily extent.
20 days (21.74%) have recorded the second lowest.
19 days (20.65%) have recorded the third lowest.
66 days (71.74%) in total have been among the three lowest on record.


CT Area:
12,992,694 km2 (02 April [Day 0.2493])
Down 281,861 km2 (2.12%) from 2015 maximum-to-date of 13,274,555 km2 on 17 February [Day 0.1288].
10,758,684 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Up 2,109 km2 from previous day.
Down 23,426 km2 over past seven days (daily average: -3,347 km2).
Up 2,548 km2 for the month of April (daily average: 1,274 km2).
357,645 km2 below 2000s average for this date.
309,521 km2 below 2010s average for this date.
78,188 km2 below 2014 value for this date.
558,293 km2 below 2012 value for this date.
3rd lowest April to-date average.
3rd lowest value for the date.
7 days this year (7.61% year-to-date) have recorded the lowest daily area.
8 days (8.7%) have recorded the second lowest.
8 days (8.7%) have recorded the third lowest.
23 days in total (25%) have been among the lowest three on record.



Title: Re: 2015 sea ice area and extent data
Post by: viddaloo on April 03, 2015, 02:37:19 PM
Down 54,426 km2 for the month of April (daily average: -27,213 km2).

And with that, we're in the Top 5 for April melts already, at #5. I'm guessing #1 by the end of month.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on April 05, 2015, 08:27:17 AM
With the latest NSIDC's sea ice concentration , I expect the following changes of  CT-area:

Sat       12.981949
Sun -26.1 12.955855
Mon -109.5 12.846376

Title: Re: 2015 sea ice area and extent data
Post by: OldLeatherneck on April 05, 2015, 12:59:22 PM
Does anyone know why JAXA hasn't updated the Extent values since April 2nd??
Title: Re: 2015 sea ice area and extent data
Post by: seaicesailor on April 05, 2015, 02:16:27 PM
They are upgrading the system, in AMSR2 thread there was more info posted days ago
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on April 08, 2015, 01:25:11 PM
IJIS Extent:
13,409,765 km2 (07 April)
Down 532,295 km2 (3.82%) from 2015 maximum-to-date of 13,942,060 km2 on 15 February.
10,232,310 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Down 36,123 km2 from previous day.
Down 255,546 km2 over past seven days (daily average: -36,507 km2).
Down 255,546 km2 for the month of April (daily average: -36,507 km2).
650,040 km2 below 2000s average for this date.
519,670 km2 below 2010s average for this date.
424,108 km2 below 2014 value for this date.
803,395 km2 below 2012 value for this date.
Lowest April to-date average.
Lowest value for the date.
32 days this year (32.99% year-to-date) have recorded the lowest daily extent.
20 days (20.62%) have recorded the second lowest.
19 days (19.59%) have recorded the third lowest.
71 days (73.2%) in total have been among the three lowest on record.


CT Area:
12,806,602 km2 (07 April [Day 0.2631])
Down 467,954 km2 (3.53%) from 2015 maximum-to-date of 13,274,555 km2 on 17 February [Day 0.1288].
10,572,592 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Up 9,091 km2 from previous day.
Down 183,544 km2 over past seven days (daily average: -26,221 km2).
Down 183,544 km2 for the month of April (daily average: -26,221 km2).
434,604 km2 below 2000s average for this date.
312,872 km2 below 2010s average for this date.
235,239 km2 below 2014 value for this date.
430,447 km2 below 2012 value for this date.
2nd lowest April to-date average.
2nd lowest value for the date.
7 days this year (7.22% year-to-date) have recorded the lowest daily area.
11 days (11.34%) have recorded the second lowest.
8 days (8.25%) have recorded the third lowest.
26 days in total (26.8%) have been among the lowest three on record.

Title: Re: 2015 sea ice area and extent data
Post by: BornFromTheVoid on April 08, 2015, 01:42:49 PM
Update for the week to April 4th

The current 5 day mean is on 14,259,400km2 while the 1 day extent is at 14,156,000km2.
The daily anomaly (compared to 81-10) is at -908,920km2, an increase from -907,130km2 last week. The anomaly compared to the 07, 11 and 12 average is at -349,600km2, an increase from -239,070km2 last week. We're currently 3rd lowest on record, the same as last week.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2F4OXg1Y7.png&hash=a59a1496b22ac3baaecf2382842982b6)

The average daily change over the last 7 days was -23.1k/day, compared to the long term average of -22.9k/day, and the 07, 11 and 12 average of -7.3k/day.
The average long term change over the next week is -35.2k/day, with the 07, 11, and 12 average being -33.6k/day.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FQe8pPul.png&hash=88e2204263cbca99f8d57ef3a6a6230f)

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FJTx3QTW.png&hash=f8455faa24760a089eb36ec7258d5927)

The loss so far this April is the 18th largest on record. To achieve the largest recorded monthly loss, at least -61.4k/day is required, while the smallest loss requires less than -23.2k/day and an average requires a loss of -39.9k/day.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2Fv0uOxAo.png&hash=fb180a47727f7359ff2924833f02ceb5)

The change this March was the 12th least negative on record, while the average monthly extent was the lowest on record.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2Fb7tzdse.png&hash=fb745dc6733a53312df97db2b4db7028)

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FuCfPu6k.png&hash=675a2da4cdfce1a47127380fd41d0672)
Title: Re: 2015 sea ice area and extent data
Post by: crandles on April 08, 2015, 05:32:20 PM
NSIDC 13.999 on 7th April. Previous earliest for below 14million km^2 was 9th April 2006
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on April 12, 2015, 02:53:14 PM
IJIS Extent:
13,446,594 km2 (11 April)
Down 495,466 km2 (3.55%) from 2015 maximum-to-date of 13,942,060 km2 on 15 February.
10,269,139 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Up 14,264 km2 from previous day.
Down 57,666 km2 over past seven days (daily average: -8,238 km2).
Down 218,717 km2 for the month of April (daily average: -19,883 km2).
444,533 km2 below 2000s average for this date.
387,300 km2 below 2010s average for this date.
182,088 km2 below 2014 value for this date.
589,612 km2 below 2012 value for this date.
2nd lowest April to-date average.
3rd lowest value for the date.
32 days this year (31.68% year-to-date) have recorded the lowest daily extent.
23 days (22.77%) have recorded the second lowest.
20 days (19.8%) have recorded the third lowest.
75 days (74.26%) in total have been among the three lowest on record.


CT Area:
12,618,747 km2 (10 April [Day 0.2712])
Down 655,808 km2 (4.94%) from 2015 maximum-to-date of 13,274,555 km2 on 17 February [Day 0.1288].
10,384,737 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Down 50,067 km2 from previous day.
Down 363,202 km2 over past seven days (daily average: -51,886 km2).
Down 371,399 km2 for the month of April (daily average: -37,140 km2).
485,154 km2 below 2000s average for this date.
435,998 km2 below 2010s average for this date.
481,592 km2 below 2014 value for this date.
525,013 km2 below 2012 value for this date.
2nd lowest April to-date average.
2nd lowest value for the date.
7 days this year (70% year-to-date) have recorded the lowest daily area.
14 days (14%) have recorded the second lowest.
8 days (8%) have recorded the third lowest.
29 days in total (29%) have been among the lowest three on record.

Title: Re: 2015 sea ice area and extent data
Post by: BornFromTheVoid on April 12, 2015, 07:33:34 PM
Update for the week to April 12th

The current 5 day mean is on 14,062,200km2 while the 1 day extent is at 14,158,000km2.
The daily anomaly (compared to 81-10) is at -859,810km2, a decrease from -908,920km2 last week. The anomaly compared to the 07, 11 and 12 average is at -311,870km2, a decrease from -349,600km2 last week. We're currently 3rd lowest on record, the same as last week.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2F0C9rJS7.png&hash=0786fc8aa79efe743f69e5a6a59aeb97)

The average daily change over the last 7 days was -28.7k/day, compared to the long term average of -35.2k/day, and the 07, 11 and 12 average of -33.6k/day.
The average long term change over the next week is -40.0k/day, with the 07, 11, and 12 average being -24.5k/day.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FQcotR23.png&hash=288faa77b06f89e941f9cb1bfd3f2fc1)

The change so far this April was the 19th least negative on record. To achieve the largest monthly drop a daily loss of at least -48.3k/day is required, while the smallest drop requires less than 14.0k/day and an average drop requires 29.0k/day.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FqbVP2X6.png&hash=00355002c4f2cf796ff3c3fb642eeb3b)
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on April 16, 2015, 01:17:12 PM
IJIS Extent:
13,355,159 km2 (15 April)
Down 586,901 km2 (4.21%) from 2015 maximum-to-date of 13,942,060 km2 on 15 February.
10,177,704 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Down 47,165 km2 from previous day.
Down 31,871 km2 over past seven days (daily average: -4,553 km2).
Down 310,152 km2 for the month of April (daily average: -20,677 km2).
365,525 km2 below 2000s average for this date.
336,560 km2 below 2010s average for this date.
72,424 km2 below 2014 value for this date.
695,371 km2 below 2012 value for this date.
2nd lowest April to-date average.
4th lowest value for the date.
32 days this year (30.48% year-to-date) have recorded the lowest daily extent.
23 days (21.9%) have recorded the second lowest.
20 days (19.05%) have recorded the third lowest.
75 days (71.43%) in total have been among the three lowest on record.

Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on April 16, 2015, 04:49:01 PM
CT has not updated for a while. From the NSIDC ice concentration data, I expect the following updates if/when it does:

Sun       12.653315
Mon +43.7 12.697045
Tue +62.2 12.759217
Wed -92.9 12.666365
Thu -35.7 12.630620
Fri -9.4 12.621183
Sat -70.2 12.550960

Title: Re: 2015 sea ice area and extent data
Post by: BornFromTheVoid on April 20, 2015, 12:07:07 PM
Update for the week to April 18th

The current 5 day mean is on 14,019,200km2 while the 1 day extent is at 13,972,000km2.
The daily anomaly (compared to 81-10) is at -623,070km2, a decrease from -859,810km2 last week. The anomaly compared to the 07, 11 and 12 average is at -183,400km2, a decrease from -311,870km2 last week. We're currently 5th lowest on record, down from 3rd lowest last week.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2Fl89zarh.png&hash=e078cc9c221efa65d437f79fefe2cbbc)

The average daily change over the last 7 days was -6.3k/day, compared to the long term average of -40.0k/day, and the 07, 11 and 12 average of -24.5k/day.
The average long term change over the next week is -36.3k/day, with the 07, 11, and 12 average being -27.4k/day.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FTymkNiE.png&hash=6225d99640ce44b5d5f24c24035667bd)

The loss so far this April is the 4th smallest on record. To achieve the largest monthly drop, a daily loss of at least 113.1k/day is required, while the smallest drop requires less than 30.3k/day and an average drop requires 66.5k/day.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2Fhohp6B7.png&hash=f32418a6e29a9b91747e2ab12fe1c9d5)
Title: Re: 2015 sea ice area and extent data
Post by: Stephen on April 21, 2015, 01:33:16 AM
CT has not updated for a while. ......


Have they explained why?  Maybe they have hangovers from an extended spring break?
Title: Re: 2015 sea ice area and extent data
Post by: Phil. on April 23, 2015, 02:52:17 PM
CT has not updated for a while. ......


Have they explained why?  Maybe they have hangovers from an extended spring break?

Noticed that they're showing a different less detailed graph and no numerical values today.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on April 25, 2015, 05:17:19 PM
I can not say that I expect anything from Cryosphere Today anymore, but this is what would/could be had:

Sun       12.653315
Mon +43.7 12.697045
Tue +62.2 12.759217
Wed -92.9 12.666365
Thu -35.7 12.630620
Fri -9.4 12.621183
Sat -64.4 12.556754
Sun -22.0 12.534755
Mon +37.9 12.572678
Tue -45.7 12.526964
Wed -74.4 12.452570
Thu -39.8 12.412783
Fri -42.0 12.370804
Sat -40.1 12.330725
Sun -116.7 12.214050
Mon -187.1 12.026918

Title: Re: 2015 sea ice area and extent data
Post by: Shared Humanity on April 25, 2015, 07:26:18 PM
Has there been any explanation as to why they have stopped reporting?
Title: Re: 2015 sea ice area and extent data
Post by: Nightvid Cole on April 25, 2015, 07:46:06 PM
CT has not updated for a while. ......


Have they explained why?  Maybe they have hangovers from an extended spring break?

After this long and still no reporting, must be a coma, not just a hangover...
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on April 26, 2015, 02:26:07 PM
IJIS Extent:
12,998,194 km2 (25 April)
Down 943,866 km2 (6.77%) from 2015 maximum of 13,942,060 km2 on 15 February.
9,820,739 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Down 112,000 km2 from previous day.
Down 345,422 km2 over past seven days (daily average: -49,346 km2).
Down 667,117 km2 for the month of April (daily average: -26,685 km2).
365,135 km2 below 2000s average for this date.
268,189 km2 below 2010s average for this date.
38,237 km2 below 2014 value for this date.
562,506 km2 below 2012 value for this date.
3rd lowest April to-date average.
3rd lowest value for the date.
32 days this year (27.83% year-to-date) have recorded the lowest daily extent.
23 days (20%) have recorded the second lowest.
21 days (18.26%) have recorded the third lowest.
76 days (66.09%) in total have been among the three lowest on record.


CT Area:
NOTE: due to the prolonged absence of official CT sea ice area data, I've instead used Wipneus' calculated area numbers for the period from 12 April through 25 April. The official numbers will be inserted if/when available. In the meantime, thanks, Wipneus!
12,214,050 km2 (25 April [Day 0.3124])
Down 1,060,505 km2 (7.99%) from 2015 maximum-to-date of 13,274,555 km2 on 17 February [Day 0.1288].
9,980,041 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Down 116,675 km2 from previous day.
Down 320,705 km2 over past seven days (daily average: -45,815 km2).
Down 776,096 km2 for the month of April (daily average: -31,044 km2).
303,019 km2 below 2000s average for this date.
234,343 km2 below 2010s average for this date.
14,052 km2 above 2014 value for this date.
662,992 km2 below 2012 value for this date.
3rd lowest April to-date average.
3rd lowest value for the date.
7 days this year (6.09% year-to-date) have recorded the lowest daily area.
14 days (12.17%) have recorded the second lowest.
13 days (11.3%) have recorded the third lowest.
34 days in total (29.57%) have been among the lowest three on record.
Title: Re: 2015 sea ice area and extent data
Post by: BornFromTheVoid on April 26, 2015, 05:15:09 PM
Update for the week to April 25th

The current 5 day mean is on 13,875,400km2 while the 1 day extent is at 13,695,000km2.
The daily anomaly (compared to 81-10) is at -512,730km2, a decrease from -623,070km2 last week. The anomaly compared to the 07, 11 and 12 average is at -135,400km2, a decrease from -183,400km2 last week. We're currently 6th lowest on record, down from 5th lowest last week.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FMivF5cX.png&hash=01aebf694de14e56203bba85cb4592cc)

The average daily change over the last 7 days was -20.5k/day, compared to the long term average of -36.3k/day, and the 07, 11 and 12 average of -27.4k/day.
The average long term change over the next week is -54.8k/day, with the 07, 11, and 12 average being -60.6k/day.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FRolPWFB.png&hash=070b2f76a0fc467d15364b7434d7219e)

The loss so far this April is the 2nd smallest on record. To achieve the largest monthly drop, a daily loss of at least 242.6k/day is required, while the smallest drop requires less than 44.0k/day and an average drop requires 130.9k/day.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FI9Me9Ga.png&hash=66212a61e35008dbd7880965f14a5405)
Title: Re: 2015 sea ice area and extent data
Post by: James Lovejoy on April 26, 2015, 08:00:58 PM
I emailed CT asking about the 'pause' in reporting.

The reply stated it was caused by computer problems, and they hope to have them resolved this week.

Maybe we'll have new data from them this week.   :)
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on April 27, 2015, 01:40:03 PM
IJIS Extent:
12,911,507 km2 (26 April)
Down 1,030,553 km2 (7.39%) from 2015 maximum of 13,942,060 km2 on 15 February.
9,734,052 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Down 86,687 km2 from previous day.
Down 413,913 km2 over past seven days (daily average: -59,130 km2).
Down 753,804 km2 for the month of April (daily average: -28,992 km2).
403,551 km2 below 2000s average for this date.
271,687 km2 below 2010s average for this date.
67,371 km2 below 2014 value for this date.
525,399 km2 below 2012 value for this date.
3rd lowest April to-date average.
2nd lowest value for the date.
32 days this year (27.59% year-to-date) have recorded the lowest daily extent.
24 days (20.69%) have recorded the second lowest.
21 days (18.1%) have recorded the third lowest.
77 days (66.38%) in total have been among the three lowest on record.


CT Area:
NOTE: due to the prolonged absence of official CT sea ice area data, I've instead used Wipneus' calculated area numbers for the period from 12 April through 26 April. The official numbers will be inserted if/when available. In the meantime: thanks, Wipneus!
12,026,918 km2 (26 April [Day 0.3151])
Down 1,247,637 km2 (9.4%) from 2015 maximum of 13,274,555 km2 on 17 February [Day 0.1288].
9,792,909 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Down 187,132 km2 from previous day.
Down 545,760 km2 over past seven days (daily average: -77,966 km2).
Down 963,228 km2 for the month of April (daily average: -37,047 km2).
446,038 km2 below 2000s average for this date.
349,129 km2 below 2010s average for this date.
252,986 km2 below 2014 value for this date.
839,347 km2 below 2012 value for this date.
Sixth lowest April to-date average.
2nd lowest value for the date.
7 days this year (6.03% year-to-date) have recorded the lowest daily area.
15 days (12.93%) have recorded the second lowest.
13 days (11.21%) have recorded the third lowest.
35 days in total (30.17%) have been among the lowest three on record.

Title: Re: 2015 sea ice area and extent data
Post by: jdallen on April 27, 2015, 05:18:31 PM
Update for the week to April 25th...

The loss so far this April is the 2nd smallest on record. To achieve the largest monthly drop, a daily loss of at least 242.6k/day is required, while the smallest drop requires less than 44.0k/day and an average drop requires 130.9k/day.


Thank you as usual, BFtV.

I'd posit the low numbers are a direct outcome of ice missing from areas which previously, typically, would start melting out at this point in the season.

Hard to imagine another explanation, considering the anomalous persistent heat we have seen going back all the way to the end of last year's melt season.
Title: Re: 2015 sea ice area and extent data
Post by: LRC1962 on April 27, 2015, 06:27:32 PM
I'd posit the low numbers are a direct outcome of ice missing from areas which previously, typically, would start melting out at this point in the season.

Hard to imagine another explanation, considering the anomalous persistent heat we have seen going back all the way to the end of last year's melt season.
Could a possibility be that the anomalous heat over winter not affect the extent, but the thickness or rottenness of the ice? If that were the case then it would be still too cold for true melt off to occur. But latter in the season once the temps get high enough, then we could get a big melt off as the thickness/rottenness of the ice comes into effect.
Title: Re: 2015 sea ice area and extent data
Post by: Buddy on April 27, 2015, 07:02:14 PM
BINGO....

Title: Re: 2015 sea ice area and extent data
Post by: Yuha on April 27, 2015, 07:12:09 PM
I'd posit the low numbers are a direct outcome of ice missing from areas which previously, typically, would start melting out at this point in the season.

You are right.

Looking at Wipneus' extend graphs:
https://sites.google.com/site/arcticseaicegraphs/regional (https://sites.google.com/site/arcticseaicegraphs/regional)
it's clear that April losses usually come mostly from Okhotsk, Bering and Barents but this April started with exceptionally low extends in those regions. The ice that would normally melt in April was already missing in the beginning of April.

Still, in the beginning of April there was a lot of ice that could have melted during April, particularly in Okhotsk, Bering and Baffin/Newfoundland regions, but the temperatures in those areas have not been conductive to melting until the last few days. That's where the recent big drops have happened.
Title: Re: 2015 sea ice area and extent data
Post by: Neven on April 27, 2015, 09:14:19 PM
I'd posit the low numbers are a direct outcome of ice missing from areas which previously, typically, would start melting out at this point in the season.

You are right.

Looking at Wipneus' extend graphs:
https://sites.google.com/site/arcticseaicegraphs/regional (https://sites.google.com/site/arcticseaicegraphs/regional)
it's clear that April losses usually come mostly from Okhotsk, Bering and Barents but this April started with exceptionally low extends in those regions. The ice that would normally melt in April was already missing in the beginning of April.

Still, in the beginning of April there was a lot of ice that could have melted during April, particularly in Okhotsk, Bering and Baffin/Newfoundland regions, but the temperatures in those areas have not been conductive to melting until the last few days. That's where the recent big drops have happened.

Yes, the Bering has dropped of a small cliff, and the winds having blown the ice so far out, it's probably going to keep up a couple of days. And in the coming week Hudson Bay is going to experience above freezing temps. At the same time almost all of the Arctic will be enveloped by high pressure, meaning insolation, but also little transport and temps staying below zero.

In this respect it will be interesting to see what the DMI 80N temp graph does. It's still positive right now, but going down again, and we're one week away when the trend line went negative in 2013 and 2014 and stayed that way for practically the entire melting season, but more importantly: during that crucial first phase of the melting season: Melt Pond May and Jolly June (I have to think of a better one for June  ;) ).
Title: Re: 2015 sea ice area and extent data
Post by: Sebastian on April 27, 2015, 11:41:09 PM
(I have to think of a better one for June  ;) ).
Junction June? When we start to really see where the season is going.
Title: Re: 2015 sea ice area and extent data
Post by: seaicesailor on April 27, 2015, 11:47:42 PM
I'd posit the low numbers are a direct outcome of ice missing from areas which previously, typically, would start melting out at this point in the season.

You are right.

Looking at Wipneus' extend graphs:
https://sites.google.com/site/arcticseaicegraphs/regional (https://sites.google.com/site/arcticseaicegraphs/regional)
it's clear that April losses usually come mostly from Okhotsk, Bering and Barents but this April started with exceptionally low extends in those regions. The ice that would normally melt in April was already missing in the beginning of April.

Still, in the beginning of April there was a lot of ice that could have melted during April, particularly in Okhotsk, Bering and Baffin/Newfoundland regions, but the temperatures in those areas have not been conductive to melting until the last few days. That's where the recent big drops have happened.

Yes, the Bering has dropped of a small cliff, and the winds having blown the ice so far out, it's probably going to keep up a couple of days. And in the coming week Hudson Bay is going to experience above freezing temps. At the same time almost all of the Arctic will be enveloped by high pressure, meaning insolation, but also little transport and temps staying below zero.

In this respect it will be interesting to see what the DMI 80N temp graph does. It's still positive right now, but going down again, and we're one week away when the trend line went negative in 2013 and 2014 and stayed that way for practically the entire melting season, but more importantly: during that crucial first phase of the melting season: Melt Pond May and Jolly June (I have to think of a better one for June  ;) ).

The DMI 80+ temp anomaly did become negative around day 120 for 2012, 2007, and 2011 as well, and stayed so through May and June (except some days for 2011).

So I don't think that, by itself, it is such a relevant indicator. I have no real physical argument to say so,  just what the data of these other years say.
Title: Re: 2015 sea ice area and extent data
Post by: seaicesailor on April 28, 2015, 12:29:44 AM
I'd posit the low numbers are a direct outcome of ice missing from areas which previously, typically, would start melting out at this point in the season.

Hard to imagine another explanation, considering the anomalous persistent heat we have seen going back all the way to the end of last year's melt season.
Could a possibility be that the anomalous heat over winter not affect the extent, but the thickness or rottenness of the ice? If that were the case then it would be still too cold for true melt off to occur. But latter in the season once the temps get high enough, then we could get a big melt off as the thickness/rottenness of the ice comes into effect.

Chances are the ice temperature right now is higher of what would have been with lower winter temps, since this is way enthalpy anomaly during winter is retained; thickness would be lower too. However one cannot say for sure without knowledge of how much heat radiated back to space. I dont think it would affect ice or snow health or rottenness



Title: Re: 2015 sea ice area and extent data
Post by: Neven on April 28, 2015, 12:45:24 AM
(I have to think of a better one for June  ;) ).
Junction June? When we start to really see where the season is going.

That's a good one. I'll have to remember that.  :)


The DMI 80+ temp anomaly did become negative around day 120 for 2012, 2007, and 2011 as well, and stayed so through May and June (except some days for 2011).

So I don't think that, by itself, it is such a relevant indicator. I have no real physical argument to say so,  just what the data of these other years say.

You're absolutely right. Somehow I didn't look further back past 2013, or if I did, didn't pay enough attention. I often think people make too much out of the DMI 80N temp graph, and here I go doing it myself. Must be them spectacular spikes.
Title: Re: 2015 sea ice area and extent data
Post by: jai mitchell on April 28, 2015, 01:43:47 AM
we're one week away when the trend line went negative in 2013 and 2014 and stayed that way for practically the entire melting season, but more importantly: during that crucial first phase of the melting season: Melt Pond May and Jolly June (I have to think of a better one for June  ;) ).

2009-2011 also had similar dips, 2012 and 2007 had dips below the trend at earlier dates and then recovered just slightly above the trend just as it was crossing the average 0C line.

http://ocean.dmi.dk/arctic/meant80n.uk.php (http://ocean.dmi.dk/arctic/meant80n.uk.php)
Title: Re: 2015 sea ice area and extent data
Post by: Neven on April 28, 2015, 06:21:53 AM

2009-2011 also had similar dips, 2012 and 2007 had dips below the trend at earlier dates and then recovered just slightly above the trend just as it was crossing the average 0C line.

http://ocean.dmi.dk/arctic/meant80n.uk.php (http://ocean.dmi.dk/arctic/meant80n.uk.php)

There is indeed a slight difference in that 2013 and 2014 stay firmly below average, where other years from Junction June onwards hover around it.

But anyway, this should be in the melting season topic. I wasn't paying attention.
Title: Re: 2015 sea ice area and extent data
Post by: seaicesailor on April 28, 2015, 01:27:43 PM

2009-2011 also had similar dips, 2012 and 2007 had dips below the trend at earlier dates and then recovered just slightly above the trend just as it was crossing the average 0C line.

http://ocean.dmi.dk/arctic/meant80n.uk.php (http://ocean.dmi.dk/arctic/meant80n.uk.php)

There is indeed a slight difference in that 2013 and 2014 stay firmly below average, where other years from Junction June onwards hover around it.

But anyway, this should be in the melting season topic. I wasn't paying attention.

Hi Neven, I posted a comment on this in the Melting season thread to stay on topic.

Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on May 01, 2015, 01:02:32 PM
IJIS Extent:
12,707,016 km2 (30 April)
Down 1,235,044 km2 (8.86%) from 2015 maximum of 13,942,060 km2 on 15 February.
9,529,561 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Down 23,313 km2 from previous day.
Down 505,384 km2 over past seven days (daily average: -72,198 km2).
Down 958,295 km2 for the month of April (daily average: -31,943 km2).
439,986 km2 below 2000s average for this date.
278,716 km2 below 2010s average for this date.
186,699 km2 below 2014 value for this date.
451,695 km2 below 2012 value for this date.
3rd lowest April average.
2nd lowest value for the date.
33 days this year (27.5% year-to-date) have recorded the lowest daily extent.
27 days (22.5%) have recorded the second lowest.
21 days (17.5%) have recorded the third lowest.
81 days (67.5%) in total have been among the three lowest on record.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on May 03, 2015, 12:02:36 PM
While waiting for CT to restore its data stream, here is my approximation of it, with a solid century this Monday:


Sun       12.653315
Mon +43.7 12.697045
Tue +62.2 12.759217
Wed -92.9 12.666365
Thu -35.7 12.630620
Fri -9.4 12.621183
Sat -64.4 12.556754
Sun -22.0 12.534755
Mon +37.9 12.572678
Tue -45.7 12.526964
Wed -74.4 12.452570
Thu -39.8 12.412783
Fri -42.0 12.370804
Sat -40.1 12.330725
Sun -116.7 12.214050
Mon -187.4 12.026666
Tue -26.7 11.999984
Wed -14.9 11.985108
Thu +8.4 11.993483
Fri +13.9 12.007337
Sat -1.2 12.006169
Sun -7.0 11.999147
Mon -146.1 11.853065

Title: Re: 2015 sea ice area and extent data
Post by: crandles on May 03, 2015, 12:25:08 PM
Mon .3342
2006 11.5360041
2008 11.7168293
1990 11.7926712
2007 11.8036528
2013 11.8037691
2015 11.853065
2014 11.8846378
2004 11.9914856
2010 11.9924707

so 6th lowest for date
Title: Re: 2015 sea ice area and extent data
Post by: BornFromTheVoid on May 03, 2015, 07:13:22 PM
Update for the week to May 3rd

The current 5 day mean is on 13,317,400km2 while the 1 day extent is at 13,111,000km2.
The daily anomaly (compared to 81-10) is at -687,360km2, an increase from -512,730km2 last week. The anomaly compared to the 07, 11 and 12 average is at -269,070km2, an increase from -135,400km2 last week. We're currently 3rd lowest on record, down from 6th lowest last week.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FnpsYUOT.png&hash=4361713d0be47c1a650fcbc14e4b6349)

The average daily change over the last 7 days was -79.7k/day, compared to the long term average of -54.8k/day, and the 07, 11 and 12 average of -60.6k/day.
The average long term change over the next week is -50.7k/day, with the 07, 11, and 12 average being -49.4k/day.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FV4AIM5u.png&hash=9994b74fb33715d7b8083fa5baa92374)

The loss so far this May is the 4th largest on record. To achieve the largest monthly drop, a daily loss of at least 67.0k/day is required, while the smallest drop requires less than 20.3k/day and an average drop requires 43.5k/day.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FvAWTmcB.png&hash=4fdcf89ed21c690b58c65526ca9cf2cc)

The extent loss this April was the 8th smallest on record, while the average monthly extent was the 3rd lowest on record.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FffaSQaZ.png&hash=8109c24403afac440cacefcdebb181d1)


(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2F7d9vrT5.png&hash=36ddd735363fed4a616f8d3259f28f5a)
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on May 06, 2015, 04:22:26 PM
IJIS Extent:
12,523,337 km2 (05 May)
Down 1,418,723 km2 (10.18%) from 2015 maximum of 13,942,060 km2 on 15 February.
9,345,882 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Down 65,661 km2 from previous day.
Down 292,433 km2 over past seven days (daily average: -41,776 km2).
Down 183,679 km2 for the month of May (daily average: -36,736 km2).
387,229 km2 below 2000s average for this date.
196,172 km2 below 2010s average for this date.
91,075 km2 below 2014 value for this date.
306,069 km2 below 2012 value for this date.
3rd lowest May to-date average.
3rd lowest value for the date.
33 days this year (26.4% year-to-date) have recorded the lowest daily extent.
29 days (23.2%) have recorded the second lowest.
24 days (19.2%) have recorded the third lowest.
86 days (68.8%) in total have been among the three lowest on record.


NOTE: Cryosphere Today updated their file this morning, so all SIA data here are now official, including those data from Day 0.2767 forward.

CT Area:
11,796,725 km2 (05 May [Day 0.3397])
Down 1,477,830 km2 (11.13%) from 2015 maximum of 13,274,555 km2 on 17 February [Day 0.1288].
9,562,716 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Down 36,581 km2 from previous day.
Down 188,061 km2 over past seven days (daily average: -26,866 km2).
Down 209,744 km2 for the month of May (daily average: -41,949 km2).
186,942 km2 below 2000s average for this date.
53,701 km2 above 2010s average for this date.
2,427 km2 above 2014 value for this date.
153,401 km2 below 2012 value for this date.
7th lowest May to-date average.
8th lowest value for the date.
7 days this year (5.6% year-to-date) have recorded the lowest daily area.
15 days (12%) have recorded the second lowest.
15 days (12%) have recorded the third lowest.
37 days in total (29.6%) have been among the lowest three on record.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on May 06, 2015, 04:27:41 PM
CT is back again!

My last prediction, calculated fro NSIDC sea ice concentration data, was:


Wed -36.6 11.797073


Today CT reported:

-36k6 11.796725

That is 0.3k off (about half a "pixel" at 100%)

For Friday another century is coming:


Wed       11.796725
Thu -34.5 11.762206
Fri -169.4 11.592817

Title: Re: 2015 sea ice area and extent data
Post by: Tor Bejnar on May 06, 2015, 09:18:19 PM
With no 'truth testing', so to speak, for a month (was it that long?), that tiny discrepancy is not only cool, but outstandingly frosty!  (Cool and frosty being good for Arctic ice and therefore good for children.)
Title: Re: 2015 sea ice area and extent data
Post by: oren on May 08, 2015, 09:45:31 AM
CT is back again!

My last prediction, calculated fro NSIDC sea ice concentration data, was:


Wed -36.6 11.797073


Today CT reported:

-36k6 11.796725

That is 0.3k off (about half a "pixel" at 100%)

For Friday another century is coming:


Wed       11.796725
Thu -34.5 11.762206
Fri -169.4 11.592817


To say that your precision is impressive would be an understatement
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on May 08, 2015, 02:46:24 PM
IJIS Extent:
12,390,148 km2 (07 May)
Down 1,551,912 km2 (11.13%) from 2015 maximum of 13,942,060 km2 on 15 February.
9,212,693 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Down 34,962 km2 from previous day.
Down 316,868 km2 over past seven days (daily average: -45,267 km2).
Down 316,868 km2 for the month of May (daily average: -45,267 km2).
418,541 km2 below 2000s average for this date.
240,662 km2 below 2010s average for this date.
134,713 km2 below 2014 value for this date.
421,854 km2 below 2012 value for this date.
3rd lowest May to-date average.
3rd lowest value for the date.
33 days this year (25.98% year-to-date) have recorded the lowest daily extent.
29 days (22.83%) have recorded the second lowest.
26 days (20.47%) have recorded the third lowest.
88 days (69.29%) in total have been among the three lowest on record.


CT Area:
11,593,455 km2 (07 May [Day 0.3452])
Down 1,681,100 km2 (12.66%) from 2015 maximum of 13,274,555 km2 on 17 February [Day 0.1288].
9,359,446 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Down 169,345 km2 from previous day.
Down 413,014 km2 over past seven days (daily average: -59,002 km2).
Down 413,014 km2 for the month of May (daily average: -59,002 km2).
326,905 km2 below 2000s average for this date.
66,950 km2 below 2010s average for this date.
150,433 km2 below 2014 value for this date.
271,646 km2 below 2012 value for this date.
6th lowest May to-date average.
3rd lowest value for the date.
7 days this year (5.51% year-to-date) have recorded the lowest daily area.
15 days (11.81%) have recorded the second lowest.
16 days (12.6%) have recorded the third lowest.
38 days in total (29.92%) have been among the lowest three on record.

Title: Re: 2015 sea ice area and extent data
Post by: Buddy on May 08, 2015, 06:00:43 PM
Quote
421,854 km2 below 2012 value for this date.

THAT....will continue to be the interesting statistic to track as we head towards a new record low come September.

The only thing in my mind.....is how much lower than 2012 will it be.

Title: Re: 2015 sea ice area and extent data
Post by: andy_t_roo on May 09, 2015, 01:20:31 AM
CT is back again!

My last prediction, calculated fro NSIDC sea ice concentration data, was:


Wed -36.6 11.797073


Today CT reported:

-36k6 11.796725

That is 0.3k off (about half a "pixel" at 100%)
Do you think that this indicates that numbers displayed to that precision present false certainty?
Perhaps the last 2 didgets could be removed, leaving the last significant figure at 0.1k, or less than 1/4 a pixel. Given the resolution and noise of the data, this difference could even be caused by floating point error accumulations on a even a perfect match of the actual underlying maths. I don't believe these last 2 figures tell us anything
Title: Re: 2015 sea ice area and extent data
Post by: plinius on May 09, 2015, 12:59:56 PM
nonsensical point.
Cutting measurement digits is an as bad as widespread practice that dates back to times when people used pen and pencil to calculate their numbers. Your computer does not care about that and in fact this malpractice creates some problems (e.g. on axis rescaling). So, let him report his full numbers, your screen won't burn down, and you have hopefully the knowledge to read an error bar.
Title: Re: 2015 sea ice area and extent data
Post by: jdallen on May 09, 2015, 05:35:43 PM
Thinking about the discussion of the current state of the ice, and it's potential to pass 2012, I indulged in a quick exercise using archived IJIS data. I briefly evaluated the loss from this date for the years 2004 through 2014, and came up with the minimum, maximum and average IJIS extent loss between May 7th and the years final minumum.  I came up with this:

IJIS Extent Loss from 5/7 to Minimum, 2004-2014
Max Loss   9391972
Min Loss   7024081
Average Loss   7943161
Median Loss   8002714

I submit these values give us the effect of weather combined with "momentum" - the effect of heat previously applied (or not) during the prior 6 months or so.  From that, I think we can extrapolate  some end points which probably define the range within which the 2015 minimum will fall:


Potential 2012 Minimum based on the above numbers
2015 Minus Average Loss   4446987
2015 Minus Minimum Loss   5366067
2015 Minus Maximum Loss   2998176
2015 Minus Median Loss   4387434

I've added in median, as its offset from Average tends to reflect our trend, and what is more typical from 2007 onwards.

The upshot of this is, with a loss similar to 2012, we beat it by about 200,000KM2
With the same loss as 2004 (minimum loss), we still end up 8th lowest SIE overall, ahead of 2004 and 2006
With the average loss (Less than 2013, slightly more than 2014), we pass all years except 2007, 2011 and 2012 to take over 4th place, ditto median.

So I'd say, the most probable outcome is we end up somewhere around 2011 at the end of the melt season.  However, there is a caveat:  All the loss numbers are inside the 2SD threshold, and all but one is within 1SD of the average.  The situation is still very volatile, but I think highlights just how vulnerable things are. 

Based on that, it implies to me that there is a better than 40% chance we will pass 2012 this year.
Title: Re: 2015 sea ice area and extent data
Post by: DavidR on May 10, 2015, 02:03:21 AM
CT is back again!

My last prediction, calculated fro NSIDC sea ice concentration data, was:


Wed -36.6 11.797073


Today CT reported:

-36k6 11.796725

That is 0.3k off (about half a "pixel" at 100%)
Do you think that this indicates that numbers displayed to that precision present false certainty?
Perhaps the last 2 didgets could be removed, leaving the last significant figure at 0.1k, or less than 1/4 a pixel. Given the resolution and noise of the data, this difference could even be caused by floating point error accumulations on a even a perfect match of the actual underlying maths. I don't believe these last 2 figures tell us anything
The CT figures are ridiculously accurate.  In a system that  changes at up to  60 km^2 per minute and is measured, in each area, at different times every day; providing a figure that  is precise to  0.1 km^2 is inappropriate precision.

Wipneus is endeavoring, with great success, to replicate the CT calculations but, the CT estimates are the issue.
Title: Re: 2015 sea ice area and extent data
Post by: plinius on May 10, 2015, 11:45:15 AM
To hammer the point again: There is no such thing as "ridiculously accurate", There are only people incapable of reading an error bar.
So:
1) Cryosphere is doing very well in not cutting their digits.
2) There are more important things in life as in science than (factually wrong) rants about the number of digits reported.
Title: Re: 2015 sea ice area and extent data
Post by: Peter Ellis on May 10, 2015, 11:59:40 AM
It's not hard.  Retain all figures during processing, and when providing the raw data to others to enable further processing.   For final display products, cut it down to an appropriate number of digits to avoid implying your results are more precise than they really are.
Title: Re: 2015 sea ice area and extent data
Post by: plinius on May 10, 2015, 12:14:05 PM
I don't know how often you have dealt with scientific data yourself, but I cannot count the number of times when dear fellow scientists have cut their digits to 1 sigma and I lose information or even cannot scale to a different axis. That's ridiculous. And yes! It's not hard. But mostly I would apply that to the person not able to read the error bars.
If you want to display to people without mathemtical knowledge, you anyway use a graph.

Ever wasted a thought why natural constants are typically provided to 3 error digits and not one? Well...?
Title: Re: 2015 sea ice area and extent data
Post by: seaicesailor on May 10, 2015, 12:19:32 PM
Well, displaying decimal digits digits on integer numbers is not correct, although for practical purposes people are forgiving.
Raw data, that is the key as Peter says. Avoid processing so that the user will do is own. Rounding twice can lead to a *true* error.
Title: Re: 2015 sea ice area and extent data
Post by: BornFromTheVoid on May 10, 2015, 04:20:39 PM
Update for the week to May 10th

The current 5 day mean is on 12,927,400km2 while the 1 day extent is at 12,805,000km2.
The daily anomaly (compared to 81-10) is at -722,150km2, an increase from -687,360km2 last week. The anomaly compared to the 07, 11 and 12 average is at -313,270km2, an increase from -269,070km2 last week. We're currently 3rd lowest on record, the same as last week.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FaoRknZV.png&hash=7d7b531124dbda084a2097edaf40e50a)

The average daily change over the last 7 days was -55.7k/day, compared to the long term average of -50.7k/day, and the 07, 11 and 12 average of -49.4k/day.
The average long term change over the next week is -42.8k/day, with the 07, 11, and 12 average being -47.0k/day.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FwxBOr59.png&hash=4bce8116fdc01e55402a1b0e64a0621e)

The loss so far this May is the 11th largest on record. To achieve the largest monthly drop, a daily loss of at least 70.6k/day is required, while the smallest drop requires less than 9.0k/day and an average drop requires 39.6k/day.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FrlDLvu0.png&hash=eacb37173c165693db36bd24df14651f)
Title: Re: 2015 sea ice area and extent data
Post by: Buddy on May 10, 2015, 05:34:53 PM
BFTVoid....LOVE your stats.  Keep up the good work and THANK YOU....
Title: Re: 2015 sea ice area and extent data
Post by: helorime on May 13, 2015, 04:16:13 AM
What happened to Cryosphere today.  Site has been down all day....
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on May 13, 2015, 07:34:56 AM
CT still has not updated, here is what I calculate as what will reported when they do:


Fri       11.593455
Sat -127.6 11.465877
Sun -74.8 11.391113
Mon -106.6 11.284509
Tue -81.8 11.202744
Wed -28.3 11.174434
Thu -71.5 11.102919

Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on May 13, 2015, 12:42:37 PM
IJIS Extent:
11,983,392 km2 (12 May)
Down 1,958,668 km2 (14.05%) from 2015 maximum of 13,942,060 km2 on 15 February.
8,805,937 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Down 73,327 km2 from previous day.
Down 539,945 km2 over past seven days (daily average: -77,135 km2).
Down 723,624 km2 for the month of May (daily average: -60,302 km2).
563,174 km2 below 2000s average for this date.
288,687 km2 below 2010s average for this date.
181,797 km2 below 2014 value for this date.
561,660 km2 below 2012 value for this date.
3rd lowest May to-date average.
Lowest value for the date.
35 days this year (26.52% year-to-date) have recorded the lowest daily extent.
31 days (23.48%) have recorded the second lowest.
27 days (20.45%) have recorded the third lowest.
93 days (70.45%) in total have been among the three lowest on record.


CT Area:
NOTE: due to (yet another) prolonged absence of official CT sea ice area data, I'm instead using Wipneus' calculated area numbers for the period from 08 May through 12 May (0.3479-0.3589). The official numbers will be inserted if/when available. In the meantime, thanks, Wipneus!
11,174,434 km2 (12 May [Day 0.3589])
Down 2,100,121 km2 (15.82%) from 2015 maximum of 13,274,555 km2 on 17 February [Day 0.1288].
8,940,425 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Down 28,310 km2 from previous day.
Down 622,291 km2 over past seven days (daily average: -88,899 km2).
Down 832,035 km2 for the month of May (daily average: -69,336 km2).
496,295 km2 below 2000s average for this date.
204,268 km2 below 2010s average for this date.
243,553 km2 below 2014 value for this date.
451,665 km2 below 2012 value for this date.
3rd lowest May to-date average.
3rd lowest value for the date.
7 days this year (5.3% year-to-date) have recorded the lowest daily area.
15 days (11.36%) have recorded the second lowest.
21 days (15.91%) have recorded the third lowest.
43 days in total (32.58%) have been among the lowest three on record.
Title: Re: 2015 sea ice area and extent data
Post by: Buddy on May 13, 2015, 01:09:23 PM
WOW.  Something to chew on when looking at May 7th vs May 12th......for that 5 day period:
==============================================================

IJIS Current extent 421,854 km2 below 2012 for May 7th
IJIS Current extent 561,660 km2 below 2012 for May 12th

Additional 140,000 (rounded) loss compared to record year of 2012 (28,000 km2 per day)
-------------------------------------------------------------------------------------------

CT Area 271,646 km2 below 2012 for May 7th
CT Area 451,665 km2 below 2012 for May 12th

Additional 180,000 (rounded) loss compared to record year of 2012 (36,000 km2 per day)


And the beat goes on.........


 
Title: Re: 2015 sea ice area and extent data
Post by: Yuha on May 13, 2015, 04:50:20 PM

IJIS Current extent 561,660 km2 below 2012 for May 12th

[...]

CT Area 451,665 km2 below 2012 for May 12th


Almost all of the difference to 2012 comes from just one region: Bering. Eyeballing the regional graphs (https://sites.google.com/site/arcticseaicegraphs/regional) of Wipneus (not the same but likely similar to IJIS and CT), the difference in Bering is about 500,000 km2 in extent and about 400,000 km2 in area.
Title: Re: 2015 sea ice area and extent data
Post by: oren on May 13, 2015, 08:34:57 PM

IJIS Current extent 561,660 km2 below 2012 for May 12th

[...]

CT Area 451,665 km2 below 2012 for May 12th


Almost all of the difference to 2012 comes from just one region: Bering. Eyeballing the regional graphs (https://sites.google.com/site/arcticseaicegraphs/regional) of Wipneus (not the same but likely similar to IJIS and CT), the difference in Bering is about 500,000 km2 in extent and about 400,000 km2 in area.

Besides Bering, which makes up most of the anomaly, the CAA and Hudson have both taken an early dip in those graphs. It's still tiny, but might be interesting if it develops further.
Title: Re: 2015 sea ice area and extent data
Post by: jdallen on May 13, 2015, 10:12:04 PM
What happened to Cryosphere today.  Site has been down all day....
I tracked down contact information for the Atmospheric Sciences department at UIL, and emailed who I think are the principles, as well as sending a note to the "generic" inbox.

If I get anything back, I'll let you know.

Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on May 14, 2015, 04:39:32 PM
No update yet, my calculations indicate an uptick on Saturday (thanks to some Beaufort "recovery"):

Fri       11.593455
Sat -127.6 11.465877
Sun -74.8 11.391113
Mon -106.6 11.284509
Tue -81.8 11.202744
Wed -28.3 11.174434
Thu -71.4 11.102998
Fri -41.9 11.061100
Sat +52.5 11.113586

Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on May 15, 2015, 01:44:18 PM
Cross-posted from teh IJIS thread:

No extent number this morning; just a redirect to IJIS's twitter feed. The most recent tweets:

ADSは大規模メンテナンスを行うため5月15日12:00から5月20日12:00までサービスを停止させます。メンテナンス状況についてTwitterでアナウンスいたします。

(ADS will stop the service from May 15 12:00 order to carry out large-scale maintenance to 12:00 May 20 . For maintenance situation will announce on Twitter.)

...followed by:

本日12:00よりADSのサービスは停止させております。大規模メンテナンスを実行中です。

(ADS of service from 12:00 today , we have to stop . We are running a large-scale maintenance .)

So if I'm reading this correctly: no extent numbers until next week. Which, even coupled with the lack of CT area numbers, is no big deal; it's not like it's the melt season or anything... :)
Title: Re: 2015 sea ice area and extent data
Post by: epiphyte on May 15, 2015, 09:21:04 PM
Does anyone know if it's just the back-end that they are doing maintenance on, or will there be a gap in the data? The former would be understandable given that they are probably getting a bunch of extra traffic due to CT's extended absence...

If the latter - then it seems that they probably picked the worst possible time.
Title: Re: 2015 sea ice area and extent data
Post by: jdallen on May 15, 2015, 11:23:43 PM
Does anyone know if it's just the back-end that they are doing maintenance on, or will there be a gap in the data? The former would be understandable given that they are probably getting a bunch of extra traffic due to CT's extended absence...

If the latter - then it seems that they probably picked the worst possible time.
I've sent mail to the CT folks asking what's going on. No response as yet.
Title: Re: 2015 sea ice area and extent data
Post by: Jim Hunt on May 16, 2015, 12:03:16 AM
I've had an email back from NASA:

Quote
It's nice to see the science results getting out there! The [IceBridge] sea ice thickness data hasn't finished processing yet, I'm hoping it will finish over the weekend. Once it is done it will be given to NSIDC to be published. Since this is a time sensitive project I'll push them to get it up ASAP, with luck it should be up sometime next week.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on May 16, 2015, 08:41:09 AM
Does anyone know if it's just the back-end that they are doing maintenance on, or will there be a gap in the data? The former would be understandable given that they are probably getting a bunch of extra traffic due to CT's extended absence...

If the latter - then it seems that they probably picked the worst possible time.

AMSR2 data and products are still available from Jaxa. It is just the ADS-NIPR, and perhaps only their website that is not working. Unfortunately it includes the new and now very interesting sea ice thickness/melting maps.

In the mean time, my calculation (based on Uni Hamburgs Sea Ice Concentration  from AMSR2) of extent shows -43k for 2015-05-15.
Title: Re: 2015 sea ice area and extent data
Post by: Shared Humanity on May 16, 2015, 02:24:29 PM
If I didn't know better, I'd say the site problems are the result of a coordinated attack to blind us from what is happening during this melt season.

(Adjusts foil cap.)
Title: Re: 2015 sea ice area and extent data
Post by: Jim Hunt on May 16, 2015, 05:42:47 PM
The CT web site is up and running once again. The data currently only goes as far as May 8th though.
Title: Re: 2015 sea ice area and extent data
Post by: Vergent on May 16, 2015, 06:05:06 PM
An hour ago , it was the 7th, now, it's the 9th.....Looks like by the end of the day, they will be up to date.
Title: Re: 2015 sea ice area and extent data
Post by: Jim Hunt on May 16, 2015, 08:56:51 PM
They have caught up, to reveal this (http://arctic.atmos.uiuc.edu/cryosphere/arctic.sea.ice.interactive.html) (with the noise removed)
Title: Re: 2015 sea ice area and extent data
Post by: Stephen on May 17, 2015, 03:14:20 AM
There's that uptick as predicted by Wipneus.   

That image also nicely exposes some of the nonsense that was being spoken during the winter maximum.  The raw numbers of area and extent during the winter maximum seem to have any correlation at all to the numbers in May when they all converge. 
Title: Re: 2015 sea ice area and extent data
Post by: jdallen on May 17, 2015, 05:24:32 AM
There's that uptick as predicted by Wipneus.   

That image also nicely exposes some of the nonsense that was being spoken during the winter maximum.  The raw numbers of area and extent during the winter maximum seem to have any correlation at all to the numbers in May when they all converge.
Careful.  They may all have close to the same slope, but check the offsets carefully at the same juncture. I see differences.

I think also you need to consider the impact of missing ice will have on how things melt out. That's yet to be determined, but really isn't starting well at all.
Title: Re: 2015 sea ice area and extent data
Post by: Stephen on May 17, 2015, 06:49:25 AM
There's that uptick as predicted by Wipneus.   

That image also nicely exposes some of the nonsense that was being spoken during the winter maximum.  The raw numbers of area and extent during the winter maximum seem to have any correlation at all to the numbers in May when they all converge.
Careful.  They may all have close to the same slope, but check the offsets carefully at the same juncture. I see differences.

I think also you need to consider the impact of missing ice will have on how things melt out. That's yet to be determined, but really isn't starting well at all.

My point is that none of those differences could have been predicted just by looking at the winter maximum figures. 
Title: Re: 2015 sea ice area and extent data
Post by: epiphyte on May 17, 2015, 07:39:31 AM
@stephen - your point re: the pointlessness of extrapolating from winter extent/area is well-taken.

Still, It's not winter now - and extent convergence with past years notwithstanding, things do appear to be shaping up into something which, whilst far from predictable, seems potentially outside the bounds of past experience.

I've used this analogy before - but not this early in the year... The CAB ice looks stretched; thin. In the words of Bilbo Baggins: "Like butter spread over too much bread."

...and it's only getting more diaphanous. If things keep going the way they have so far, I think this might be the year that it all comes home to roost.

Title: Re: 2015 sea ice area and extent data
Post by: DavidR on May 17, 2015, 10:20:50 AM
@stephen - your point re: the pointlessness of extrapolating from winter extent/area is well-taken.

Still, It's not winter now - and extent convergence with past years notwithstanding, things do appear to be shaping up into something which, whilst far from predictable, seems potentially outside the bounds of past experience.

One of the interesting aspects of this year is that so far it has not been a particularly warm year across the arctic, unlike 2014 which was comparatively  warm throughout Feb- Apr.  April was only about  12th warmest and February 15th.  March  was 4th  but still cooler than 2014. 
Despite this the rate of melt  has been strong. But ultimately it is the arctic temperature from now on that  will  determine the final melt.
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on May 17, 2015, 02:30:10 PM

CT Area:
10,987,263 km2 (16 May [Day 0.3699])
Down 2,287,293 km2 (17.23%) from 2015 maximum of 13,274,555 km2 on 17 February [Day 0.1288].
8,753,253 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Down 126,201 km2 from previous day.
Down 403,355 km2 over past seven days (daily average: -57,622 km2).
Down 1,019,206 km2 for the month of May (daily average: -63,700 km2).
463,569 km2 below 2000s average for this date.
102,325 km2 below 2010s average for this date.
119,246 km2 below 2014 value for this date.
193,752 km2 below 2012 value for this date.
3rd lowest May to-date average.
3rd lowest value for the date.
7 days this year (5.15% year-to-date) have recorded the lowest daily area.
16 days (11.76%) have recorded the second lowest.
23 days (16.91%) have recorded the third lowest.
46 days in total (33.82%) have been among the lowest three on record.
Title: Re: 2015 sea ice area and extent data
Post by: Frivolousz21 on May 17, 2015, 02:57:39 PM
CT area might see some massive drops as the torch spreads to over half the Pacific.   Ct concentration will drop.

Title: Re: 2015 sea ice area and extent data
Post by: BornFromTheVoid on May 17, 2015, 04:07:43 PM
Update for the week to May 17th

The current 5 day mean is on 12,632,800km2 while the 1 day extent is at 12,531,000km2.
The daily anomaly (compared to 81-10) is at -717,100km2, a decrease from -722,150km2 last week. The anomaly compared to the 07, 11 and 12 average is at -278,530km2, a decrease from -313,270km2 last week. We're currently 3rd lowest on record, the same as last week.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FNAGr041.png&hash=d65dea211c5d31aec2296aacca3d04ed)

The average daily change over the last 7 days was -42.1k/day, compared to the long term average of -42.8k/day, and the 07, 11 and 12 average of -47.0k/day.
The average long term change over the next week is -46.5k/day, with the 07, 11, and 12 average being -42.8k/day.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FNdL6Qun.png&hash=3b9c202f5b9b48540e56b78552d99e52)

The loss so far this May is the 14th largest on record. To achieve the largest monthly drop, a daily loss of at least 83.9k/day is required, while the smallest drop requires less than 6.4k/day and an average drop requires 38.5k/day.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2F9H0Wnre.png&hash=4187e281fc01cd20d821fb9f83fa66c4)
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on May 18, 2015, 01:00:39 PM
FWIW, ADS_NIPR says we'll have extent numbers back on Wednesday:

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FgrvhJaD.png&hash=3fe1e3670e9f7bfcf9f1937feea81508)
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on May 19, 2015, 09:48:44 AM
Thanks Jim, the thickness data is available again as well.
The melting in the Beaufort/Chukchi seems now  to have seriously started.
Title: Re: 2015 sea ice area and extent data
Post by: Neven on May 19, 2015, 11:27:37 AM
What's the grey/violet stuff?  :o
Title: Re: 2015 sea ice area and extent data
Post by: seaicesailor on May 19, 2015, 11:33:11 AM
melt ponds ?  ::)
I am obsessed and see melt ponds behind every corner
Title: Re: 2015 sea ice area and extent data
Post by: Siffy on May 19, 2015, 11:35:23 AM
Thanks Jim, the thickness data is available again as well.
The melting in the Beaufort/Chukchi seems now  to have seriously started.

A key would be much appreciated here. :)
Title: Re: 2015 sea ice area and extent data
Post by: Neven on May 19, 2015, 11:44:08 AM
melt ponds ?  ::)
I am obsessed and see melt ponds behind every corner

Indeed, that's why I ask!  ;D
Title: Re: 2015 sea ice area and extent data
Post by: Neven on May 19, 2015, 11:46:36 AM
Thanks Jim, the thickness data is available again as well.
The melting in the Beaufort/Chukchi seems now  to have seriously started.

I've decided to stop being lazy:

Title: Re: 2015 sea ice area and extent data
Post by: silkman on May 19, 2015, 12:12:39 PM
Nice pic from the Barrow webcam of shoreline melt ponds.
Title: Re: 2015 sea ice area and extent data
Post by: oren on May 19, 2015, 12:21:41 PM
Melt ponds indeed! nice pic.
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on May 19, 2015, 01:32:34 PM
IJIS Extent:
11,675,662 km2 (18 May)
Down 2,266,398 km2 (16.26%) from 2015 maximum of 13,942,060 km2 on 15 February.
8,498,207 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Down 75,902 km2 from previous day.
Down 381,057 km2 over past seven days (daily average: -54,437 km2).
Down 1,031,354 km2 for the month of May (daily average: -57,297 km2).
598,255 km2 below 2000s average for this date.
319,029 km2 below 2010s average for this date.
244,602 km2 below 2014 value for this date.
490,401 km2 below 2012 value for this date.
2nd lowest May to-date average.
Lowest value for the date.
41 days this year (29.71% year-to-date) have recorded the lowest daily extent.
31 days (22.46%) have recorded the second lowest.
27 days (19.57%) have recorded the third lowest.
99 days (71.74%) in total have been among the three lowest on record.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on May 19, 2015, 04:37:17 PM
CT is not back to daily updates yet. Here are the expected values missing and coming:


Sun       10.987263
Mon -11.8 10.975422
Tue -118.6 10.856866
Wed -15.0 10.841865
Thu -75.4 10.766505


BTW, from that -75k4, Beaufort's contribution is negative: it increases +39k.
Title: Re: 2015 sea ice area and extent data
Post by: Gray-Wolf on May 19, 2015, 06:18:37 PM
Could this be the collapse and spread of the agglomerate ice floes as the FY ice cement melts out/fails? The modis images show 'large floes' riddled with fractures and I have to wonder if this is a patchwork of survival floes glued together with FY ice? This does not bode well as that 'thick,good' ice could really be Swiss cheese remnants of previous seasons in-filled with FY ice?

It often occurs with Bering at the start of the season as the ice breaks up and flows south extending the 15 or 30% threshold and we see ( what I call) 'false gains'.

Sadly we did not see this this year as ice in Bering was absent ( warm water influx, via the Alaskan current, from 'the blob' keeping ice formation at a min?).
Title: Re: 2015 sea ice area and extent data
Post by: seaicesailor on May 19, 2015, 07:32:10 PM
Could this be the collapse and spread of the agglomerate ice floes as the FY ice cement melts out/fails? The modis images show 'large floes' riddled with fractures and I have to wonder if this is a patchwork of survival floes glued together with FY ice? This does not bode well as that 'thick,good' ice could really be Swiss cheese remnants of previous seasons in-filled with FY ice?

It often occurs with Bering at the start of the season as the ice breaks up and flows south extending the 15 or 30% threshold and we see ( what I call) 'false gains'.

Sadly we did not see this this year as ice in Bering was absent ( warm water influx, via the Alaskan current, from 'the blob' keeping ice formation at a min?).

There has been area increase, not extent.
I assume tomorrow twice as much decrease than today's increase. CT area is very noisy day by day at regional level.

Those floes are huge, bear in mind, Manhattan-like floes
Title: Re: 2015 sea ice area and extent data
Post by: BornFromTheVoid on May 19, 2015, 07:55:17 PM
Daily NSIDC extent now lowest on record. The 5 day trailing average should be 2nd lowest tomorrow and possibly lowest on record the day after, if moderate extent drops continue.
Title: Re: 2015 sea ice area and extent data
Post by: jdallen on May 19, 2015, 08:30:42 PM
Daily NSIDC extent now lowest on record. The 5 day trailing average should be 2nd lowest tomorrow and possibly lowest on record the day after, if moderate extent drops continue.

Low extent start, early push to get moving, average losses from there already suggests we end up between 2011 and 2012... If we are lucky.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on May 20, 2015, 07:07:34 AM
From the ADS-NIPR Jaxa thickness/melting map, a new animation of the progressing melt in the Beaufort & Chukchi regions. The "bare" images seems to cause some confusion, so I have added the color bars.

(click req'd)
Title: Re: 2015 sea ice area and extent data
Post by: James Lovejoy on May 20, 2015, 08:42:32 AM
Is that huge growth melt ponds?  Even so very impressive.

What's I find even more impressive in your animation is the reduction of thickness in just 4 days.  If that keeps up, it's not looking good for the ice this year.

Title: Re: 2015 sea ice area and extent data
Post by: jdallen on May 20, 2015, 09:26:14 AM
From the ADS-NIPR Jaxa thickness/melting map, a new animation of the progressing melt in the Beaufort & Chukchi regions. The "bare" images seems to cause some confusion, so I have added the color bars.

(click req'd)
Dang if that melt channel driving into the pack from the Bering Strait doesn't look like it's following a current...

Though when I think about it, there's been a lot of rain getting driven north straight up along this line.  It's the remains of the cyclones being driven north along the Asian coast, shattering against the high pressure ridge over the North American coast, and then getting punted north into the pack.  That's where the moisture is coming from.

It's been pretty steady, and just by itself would add a large amount of water on top of the pack, as well as accelerating snow melt.

Regardless, the conclusion is very bad news.
Title: Re: 2015 sea ice area and extent data
Post by: anthropocene on May 20, 2015, 09:35:37 AM
From the ADS-NIPR Jaxa thickness/melting map, a new animation of the progressing melt in the Beaufort & Chukchi regions. The "bare" images seems to cause some confusion, so I have added the color bars.

(click req'd)
Dang if that melt channel driving into the pack from the Bering Strait doesn't look like it's following a current...

Though when I think about it, there's been a lot of rain getting driven north straight up along this line.  It's the remains of the cyclones being driven north along the Asian coast, shattering against the high pressure ridge over the North American coast, and then getting punted north into the pack.  That's where the moisture is coming from.

It's been pretty steady, and just by itself would add a large amount of water on top of the pack, as well as accelerating snow melt.

Regardless, the conclusion is very bad news.


Interesting - most of your post is not visible to me - but is here in the quote.
Looks exactly like the plume of water you would get from a narrow constraint - Bering Straits or river outflow? Either way is anybody else getting a sinking feeling about the future of the ice this summer? Is my geography correct and this is the area where the 'protective MYI' arm is supposed to be?

Many thanks for the animation Wipneus.
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on May 20, 2015, 01:09:19 PM
IJIS Extent:
11,611,102 km2 (19 May)
Down 2,330,958 km2 (16.72%) from 2015 maximum of 13,942,060 km2 on 15 February.
8,433,647 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Down 64,560 km2 from previous day.
Down 372,290 km2 over past seven days (daily average: -53,184 km2).
Down 1,095,914 km2 for the month of May (daily average: -57,680 km2).
600,717 km2 below 2000s average for this date.
326,818 km2 below 2010s average for this date.
261,754 km2 below 2014 value for this date.
505,755 km2 below 2012 value for this date.
2nd lowest May to-date average.
Lowest value for the date.
42 days this year (30.22% year-to-date) have recorded the lowest daily extent.
31 days (22.3%) have recorded the second lowest.
27 days (19.42%) have recorded the third lowest.
100 days (71.94%) in total have been among the three lowest on record.


CT Area:
10,841,481 km2 (19 May [Day 0.3781])
Down 2,433,074 km2 (18.33%) from 2015 maximum of 13,274,555 km2 on 17 February [Day 0.1288].
8,607,472 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Down 14,870 km2 from previous day.
Down 332,382 km2 over past seven days (daily average: -47,483 km2).
Down 1,164,988 km2 for the month of May (daily average: -61,315 km2).
400,353 km2 below 2000s average for this date.
101,299 km2 below 2010s average for this date.
88,136 km2 below 2014 value for this date.
158,307 km2 below 2012 value for this date.
3rd lowest May to-date average.
2nd lowest value for the date.
7 days this year (5.04% year-to-date) have recorded the lowest daily area.
18 days (12.95%) have recorded the second lowest.
24 days (17.27%) have recorded the third lowest.
49 days in total (35.25%) have been among the lowest three on record.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on May 21, 2015, 07:09:07 AM
Here is an update of the previous animation.

(still needs a click!)
Title: Re: 2015 sea ice area and extent data
Post by: seaicesailor on May 21, 2015, 08:45:25 AM
These maps dont seem very reliable unless average thickness values are taken by Jaxa, say weekly. That'd be stable (accuracy is another thing)
Title: Re: 2015 sea ice area and extent data
Post by: Jim Hunt on May 21, 2015, 05:09:39 PM
Unless my eyes deceive me the NSIDC 5 day average extent is now at the lowest ever level for the date, at 12.425 mio km2. JAXA and DMI 30% extent are also in that unenviable position, but unless Wipneus knows something I don't CT area hasn't quite joined the club yet. 10.7665 versus 10.7000 for day 139.
Title: Re: 2015 sea ice area and extent data
Post by: deep octopus on May 21, 2015, 05:30:14 PM
Unless my eyes deceive me the NSIDC 5 day average extent is now at the lowest ever level for the date, at 12.425 mio km2. JAXA and DMI 30% extent are also in that unenviable position, but unless Wipneus knows something I don't CT area hasn't quite joined the club yet. 10.7665 versus 10.7000 for day 139.

I believe you're correct. Zooming in on the interactive tool, 2015 is now below 2004, which was previously the record low for this period.
Title: Re: 2015 sea ice area and extent data
Post by: Jim Hunt on May 21, 2015, 06:29:16 PM
Yup. I double checked the numbers and rushed into print with this searing expose of how "Steve Goddard" has got things wrong for the umpteenth time this year:

http://GreatWhiteCon.info/2015/05/arctic-sea-ice-fails-to-track-2005-06/ (http://GreatWhiteCon.info/2015/05/arctic-sea-ice-fails-to-track-2005-06/)

Quote
Today the NSIDC 5 day average Arctic sea ice extent is in actual fact at the lowest level for the date since their records began. In view of “Steve”/Tony’s headline you may find it surprising that so is his much beloved DMI 30% extent threshold metric!
Title: Re: 2015 sea ice area and extent data
Post by: BornFromTheVoid on May 21, 2015, 07:08:43 PM
Yup. I double checked the numbers and rushed into print with this searing expose of how "Steve Goddard" has got things wrong for the umpteenth time this year:

http://GreatWhiteCon.info/2015/05/arctic-sea-ice-fails-to-track-2005-06/ (http://GreatWhiteCon.info/2015/05/arctic-sea-ice-fails-to-track-2005-06/)

Quote
Today the NSIDC 5 day average Arctic sea ice extent is in actual fact at the lowest level for the date since their records began. In view of “Steve”/Tony’s headline you may find it surprising that so is his much beloved DMI 30% extent threshold metric!

As far as I can tell, it's 11k above 2004 (14,425,200 compared to 12,414,200) but will drop to lowest on record tomorrow provided the daily data doesn't see an increase.
Title: Re: 2015 sea ice area and extent data
Post by: Jim Hunt on May 21, 2015, 07:44:08 PM
I've been comparing things CT wise. For day 140 2004 was 12.443, which is the way the Charctic chart works. Leap years have a lot to answer for!
Title: Re: 2015 sea ice area and extent data
Post by: BornFromTheVoid on May 21, 2015, 07:54:35 PM
Ah, feckin' leap years. I'll stick with having a gap in my graphs!
Title: Re: 2015 sea ice area and extent data
Post by: Jim Hunt on May 21, 2015, 08:39:58 PM
Leap years or not "Goddard" is headlining DMI 30%, and that metric is at an all time low whichever way you look at it.
Title: Re: 2015 sea ice area and extent data
Post by: Lord M Vader on May 21, 2015, 08:53:12 PM
Next year is a leap year... :P

Title: Re: 2015 sea ice area and extent data
Post by: Stephen on May 22, 2015, 02:22:34 AM
Next year is a leap year... :P

Yes, and so was 2012 - which was the all time low.

Soooo....based on a sample size of one, I've got a theory that leap years mean low ice extent.  because there's more days for melt.  ;)
Title: Re: 2015 sea ice area and extent data
Post by: ktonine on May 22, 2015, 03:21:22 AM
Next year is a leap year... :P

Yes, and so was 2012 - which was the all time low.

Soooo....based on a sample size of one, I've got a theory that leap years mean low ice extent.  because there's more days for melt.  ;)

But the extra day is in the winter - so an extra day for freezing.  Back to the drawing board :)
Title: Re: 2015 sea ice area and extent data
Post by: themgt on May 22, 2015, 05:34:13 AM
Quote
But the extra day is in the winter - so an extra day for freezing.

The effect of the leap day is to give the appearance you are further into the year than is actually the case. Which exact day is added is irrelevant as long as you're after it in the calendar.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on May 22, 2015, 08:10:08 AM
In the updated ADS-NIPR AMSR2 thickness melting map animation  the melting area have moved from Beaufort to Chukchi.

(sorry, still needs a click)
Title: Re: 2015 sea ice area and extent data
Post by: slow wing on May 22, 2015, 11:32:43 AM
These maps are great, thanks Wipneus!

The Arctic basin just inside the Bering Strait has been blasted for several days with ~30 kph winds at just above freezing, so it makes sense to see melt ponds there in the last frame.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on May 22, 2015, 04:33:07 PM
My estimated CT values for the next two days are:


Fri       10.633383
Sat -56.3 10.577099
Sun +7.9 10.585019


The small uptick on Sunday is despite declines in Chukchi (-32k) and ESS (-20k). These are more than compensated by a large increase in apparent concentration in the CAB: +59k!
Title: Re: 2015 sea ice area and extent data
Post by: epiphyte on May 23, 2015, 06:45:19 AM
In the updated ADS-NIPR AMSR2 thickness melting map animation  the melting area have moved from Beaufort to Chukchi.

(sorry, still needs a click)

Going frame by frame through this GIF - in some places the changes from day to day are plainly implausible. E.g. towards the bottom right there's an area which goes from green to deep blue to yellow to red in the course of four days. According to the legend that means 1.5m -> melting @ 50% concentration -> 2.5m ->3.5m. Yet adjacent to it there is another area which remains constant throughout.

What are we to infer from that?. Perhaps that the thickness of the ice is within the margin of error of the measurement, which is too imprecise to tell us anything useful?



Title: Re: 2015 sea ice area and extent data
Post by: jdallen on May 23, 2015, 07:51:26 AM
In the updated ADS-NIPR AMSR2 thickness melting map animation  the melting area have moved from Beaufort to Chukchi.

(sorry, still needs a click)

... <snippage>

What are we to infer from that?...

Melt ponds. 

My guess is, water on the ice is messing up the sensing, and returning a signal that's interpreted as open water.
Title: Re: 2015 sea ice area and extent data
Post by: andy_t_roo on May 24, 2015, 05:13:18 AM
What are we to infer from that?. Perhaps that the thickness of the ice is within the margin of error of the measurement, which is too imprecise to tell us anything useful?
perhaps leads opening up could change the average thickness quite rapidly ; if this visualisation is tuned so that the volume of ice is correct, and there's a few hundred m of open water, then the "thickness" could fluctuate quite rapidly as the concentration of ice is diffused; if someone calculated the divergence of the motion field we could quantify that effect.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on May 24, 2015, 04:11:04 PM
CT area is expected to drop a century tomorrow, followed by a small uptick. This variation originates from the Chukchi, ESS, CAB and  Beaufort regions.

Sun       10.585287
Mon -105.2 10.480083
Tue +4.8 10.484921

Title: Re: 2015 sea ice area and extent data
Post by: BornFromTheVoid on May 24, 2015, 07:54:11 PM
Update for the week to May 23rd

The current 5 day mean is on 12,274,800km2 while the 1 day extent is at 12,152,000km2.
The daily anomaly (compared to 81-10) is at -750,430km2, an increase from -717,100km2 last week. The anomaly compared to the 07, 11 and 12 average is at -337,470km2, an increase from -278,530km2 last week. We're currently lowest on record, up from 3rd lowest last week.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FKYDrmpX.png&hash=c63d71ab62fdbead8d216376aeb7d9ed)

The average daily change over the last 7 days was -51.3k/day, compared to the long term average of -46.5k/day, and the 07, 11 and 12 average of -42.8k/day.
The average long term change over the next week is -39.9k/day, with the 07, 11, and 12 average being -46.7k/day.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FaCEQpEB.png&hash=3cc44f0b06d89ecc15db6c83e2e113f3)

The loss so far this May is the 13th largest on record. To achieve the largest monthly drop, a daily loss of at least 112.5k/day is required, while the smallest drop requires an increase more than 56.8k/day and an average drop requires a loss of 27.3k/day.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2Fc36m74m.png&hash=9654dd59522b682046529feb0918e5cc)
Title: Re: 2015 sea ice area and extent data
Post by: Peter Ellis on May 24, 2015, 08:04:53 PM
Would it be possible to use consistent colours for the years in these graphs?  It's quite difficult to compare them.  Additionally, the yellow colour for 2015 in the second graph is essentially invisible on my monitor.
Title: Re: 2015 sea ice area and extent data
Post by: epiphyte on May 25, 2015, 05:37:52 AM
What are we to infer from that?. Perhaps that the thickness of the ice is within the margin of error of the measurement, which is too imprecise to tell us anything useful?
perhaps leads opening up could change the average thickness quite rapidly ; if this visualisation is tuned so that the volume of ice is correct, and there's a few hundred m of open water, then the "thickness" could fluctuate quite rapidly as the concentration of ice is diffused; if someone calculated the divergence of the motion field we could quantify that effect.

@andy_t_roo  - I don't think it's that sophisticated! - even if it was, the visible open water in those areas isn't fluctuating that rapidly.

@jdallen - I think you're probably right that water on the surface isn't distinguishable from open water... but even discounting the blue areas there are still many places which show thickening over the past week, and/or >1-2m thickness where MODIS shows either open water, or ice which was formed over leads which opened up in April, has no snow cover, and is still so translucent as to have low albedo.

I've posted variations on this theme many times before and I'll probably keep on doing so for a while yet; The closer we get to the endgame, the less useful the measurements and models upon which we have heretofore relied will turn out to be. It's not because they aren't good techniques, it's because all measurements have a bounded margin of error. So the closer the actual value gets to zero, the less likely it is that the question "Is the value more than 0.0001" will be answered correctly.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on May 25, 2015, 08:04:17 AM
Updated the animation of the AMSR2 thickness/melting map from ADS-NIPR with three more days. The signs of early melting seem to have stalled (and 2015 is now actually behind 2013 and 2014).

[EDIT: forgot to mention that the animation will start only after a click (or tap)]
Title: Re: 2015 sea ice area and extent data
Post by: ChrisReynolds on May 25, 2015, 08:53:15 AM
Epiphyte,

The first thing I noticed was the variabiity of thickness in those ADS-NIPR AMSR2 thickness plots. My initial thought was that a per grid box multi-day average might help smooth and bring out real changes. An alternate apporach might be numeric regional data, assuming the errors do not have large spatial characteristics.

I have been unable to find documentation so cannot comment on the estimated uncertainty, but I agree with your assessment that it probably encompasses most of the range of thickness seen through the early melt season.

Wipneus,

Thanks for you work in producing those ADS-NIPR AMSR2 thickness plots, the rough thickness over wide areas is pretty much what I expected.
Title: Re: 2015 sea ice area and extent data
Post by: ktonine on May 25, 2015, 08:56:32 AM
Locating IMB Buoy 2015A on the AMSR2 map:

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi256.photobucket.com%2Falbums%2Fhh197%2Fktonine%2F2015A%2520on%2520AMSR.jpg&hash=6e634474ed821bc57aef8252d7b4257e)

And 2015A gives this view:
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fipab.apl.washington.edu%2Fcamera1.jpg&hash=2ecd0bf231722f118b9ef1b1b44bb887)

Per 2015As datastream snowmelt began in the middle of May.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on May 25, 2015, 09:53:54 AM

I have been unable to find documentation so cannot comment on the estimated uncertainty,

I did. They compare the uncertainty to be about the same as IceSat and about twice that of CryoSat2 (as specified in the Laxon et al paper). Those are single qualifications not quite covering all uncertainties and possibilities. I am still trying to find some time to write something up. In the mean time try not to look at all the noise, I find there is plenty of signal to be seen.
Title: Re: 2015 sea ice area and extent data
Post by: ChrisReynolds on May 25, 2015, 01:57:25 PM
Thanks Wipneus,

I have indeed been ignoring the variation and getting a 'feel' for the underlying thickness signal.
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on May 25, 2015, 02:10:59 PM
ADS-NIPR Extent:
11,275,662 km2 (24 May)
Down 2,666,398 km2 (19.12%) from 2015 maximum of 13,942,060 km2 on 15 February.
8,098,207 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Down 40,785 km2 from previous day.
Down 475,902 km2 over past seven days (daily average: -67,986 km2).
Down 1,431,354 km2 for the month of May (daily average: -59,640 km2).
682,982 km2 below 2000s average for this date.
376,853 km2 below 2010s average for this date.
445,000 km2 below 2014 value for this date.
570,740 km2 below 2012 value for this date.
2nd lowest May to-date average.
Lowest value for the date.
47 days this year (32.64% year-to-date) have recorded the lowest daily extent.
31 days (21.53%) have recorded the second lowest.
27 days (18.75%) have recorded the third lowest.
105 days (72.92%) in total have been among the three lowest on record.


CT Area:
10,479,857 km2 (24 May [Day 0.3917])
Down 2,794,698 km2 (21.05%) from 2015 maximum of 13,274,555 km2 on 17 February [Day 0.1288].
8,245,848 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Down 105,430 km2 from previous day.
Down 496,070 km2 over past seven days (daily average: -70,867 km2).
Down 1,526,611 km2 for the month of May (daily average: -63,609 km2).
427,866 km2 below 2000s average for this date.
121,278 km2 below 2010s average for this date.
300,094 km2 below 2014 value for this date.
153,251 km2 below 2012 value for this date.
3rd lowest May to-date average.
4th lowest value for the date.
7 days this year (4.86% year-to-date) have recorded the lowest daily area.
18 days (12.5%) have recorded the second lowest.
27 days (18.75%) have recorded the third lowest.
52 days in total (36.11%) have been among the lowest three on record.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on May 26, 2015, 04:17:39 PM
CT-area day-to-day changes keep changing a lot. Today a +5k uptick, tomorrow an XL century drop and on Thursday back to -28k. Ice in Kara, ESS and Chukchi is main cause.

Tue       10.483988
Wed -151.7 10.332264
Thu -28.4 10.303902

Title: Re: 2015 sea ice area and extent data
Post by: BornFromTheVoid on May 26, 2015, 04:27:06 PM
Would it be possible to use consistent colours for the years in these graphs?  It's quite difficult to compare them.  Additionally, the yellow colour for 2015 in the second graph is essentially invisible on my monitor.

Will make a few changes for the next update so.
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on May 27, 2015, 12:55:50 PM
ADS-NIPR Extent:
11,182,043 km2 (26 May)
Down 2,760,017 km2 (19.8%) from 2015 maximum of 13,942,060 km2 on 15 February.
8,004,588 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Down 45,499 km2 from previous day.
Down 429,059 km2 over past seven days (daily average: -61,294 km2).
Down 1,524,973 km2 for the month of May (daily average: -58,653 km2).
690,859 km2 below 2000s average for this date.
360,685 km2 below 2010s average for this date.
455,533 km2 below 2014 value for this date.
560,473 km2 below 2012 value for this date.
Lowest May to-date average.
Lowest value for the date.
49 days this year (33.56% year-to-date) have recorded the lowest daily extent.
31 days (21.23%) have recorded the second lowest.
27 days (18.49%) have recorded the third lowest.
107 days (73.29%) in total have been among the three lowest on record.


CT Area:
10,332,400 km2 (26 May [Day 0.3972])
Down 2,942,155 km2 (22.16%) from 2015 maximum of 13,274,555 km2 on 17 February [Day 0.1288].
8,098,391 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Down 151,588 km2 from previous day.
Down 509,081 km2 over past seven days (daily average: -72,726 km2).
Down 1,674,069 km2 for the month of May (daily average: -64,387 km2).
464,864 km2 below 2000s average for this date.
126,635 km2 below 2010s average for this date.
268,781 km2 below 2014 value for this date.
163,662 km2 below 2012 value for this date.
3rd lowest May to-date average.
3rd lowest value for the date.
7 days this year (4.79% year-to-date) have recorded the lowest daily area.
18 days (12.33%) have recorded the second lowest.
28 days (19.18%) have recorded the third lowest.
53 days in total (36.3%) have been among the lowest three on record.

Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on May 28, 2015, 02:32:38 PM
Cryosphere Today sea ice area has certainly been exhibiting an odd and interesting waveform the past few weeks:

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FRVQR3Y3.png&hash=f950f852039232b446ea333ddf2fee0b)

Were it not for the large decrease on 21 May, we'd be looking at a near-perfect triangle wave pattern. What gives? Instrument error? Faulty processing algorithm(s)? Real and entirely coincidental phenomenon?
Title: Re: 2015 sea ice area and extent data
Post by: jdallen on May 28, 2015, 05:48:57 PM
Cryosphere Today sea ice area has certainly been exhibiting an odd and interesting waveform the past few weeks:

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FRVQR3Y3.png&hash=f950f852039232b446ea333ddf2fee0b)

Were it not for the large decrease on 21 May, we'd be looking at a near-perfect triangle wave pattern. What gives? Instrument error? Faulty processing algorithm(s)? Real and entirely coincidental phenomenon?
My two cents...

Down on "even" days, up on "odd".  Exception to the pattern is on a "1st" (May 21).  My programmers sense is tingling.  That looks to me like an algorithm issue.

The alternative that comes to mind that could be cyclical like that is the flight path of the instruments.

I think the probability of coincidence would be close to a 1 in 4000 exception - rather low.  It's far too regular.
Title: Re: 2015 sea ice area and extent data
Post by: Peter Ellis on May 28, 2015, 06:28:47 PM
OK, there are 13 line segments, each being Upward or Downward. But it's not a perfect pattern, we're allowing for one "off-pattern" day in the middle, which will affect the line segments each side of it.

Probability of getting a perfectly alternating pattern is 2^12 = 1 in 4096.

Eliminating the two segments that are affected by the "off-pattern" day brings it down to 1 in 1024.  Still quite unusual.  However, there are a lot of days in the year.  You'll see a pattern like this on average once every 3 years or so, even assuming perfectly random data.

Real data is likely to be non-random and show a significant amount of anticorrelation from one day to the next. The actual rate of melt doesn't change violently from day to day, so if one day is significantly higher or lower than (say) the weekly average, then it's likely there was some kind of transient noise process affecting the data, so the next day will be correspondingly lower/higher).

Short version is that I don't think we can say this is anything that unusual unless it goes on for another week or so. The quick way to check would be to screen the dataset for similar instances and see how common they are.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on May 28, 2015, 06:53:22 PM
I happen to watch the pattern daily, if not for the pattern but to see how close CT is to my own calculation. Here are the last three months, see how well CT matches after 7 March, the latest day NSIDC revised its concentration data.
Title: Re: 2015 sea ice area and extent data
Post by: Juan C. García on May 30, 2015, 03:37:43 AM
It is very interesting the form in which the NSIDC SIE has fallen apart on the last two weeks. It hasn't been seen in any other year. Knowing that the NSIDC June average is defined the first 7 days of June, we are going to have a huge record on NSIDC June SIE average, when it will be announced on July.

Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on May 30, 2015, 03:08:11 PM
ADS-NIPR Extent:
10,997,659 km2 (29 May)
Down 2,944,401 km2 (21.12%) from 2015 maximum of 13,942,060 km2 on 15 February.
7,820,204 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Down 68,300 km2 from previous day.
Down 375,764 km2 over past seven days (daily average: -53,681 km2).
Down 1,709,357 km2 for the month of May (daily average: -58,943 km2).
760,126 km2 below 2000s average for this date.
416,564 km2 below 2010s average for this date.
521,464 km2 below 2014 value for this date.
598,255 km2 below 2012 value for this date.
Lowest May to-date average.
Lowest value for the date.
52 days this year (34.9% year-to-date) have recorded the lowest daily extent.
31 days (20.81%) have recorded the second lowest.
27 days (18.12%) have recorded the third lowest.
110 days (73.83%) in total have been among the three lowest on record.


CT Area:
10,231,938 km2 (29 May [Day 0.4055])
Down 3,042,617 km2 (22.92%) from 2015 maximum of 13,274,555 km2 on 17 February [Day 0.1288].
7,997,929 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Down 21,935 km2 from previous day.
Down 344,866 km2 over past seven days (daily average: -49,267 km2).
Down 1,774,530 km2 for the month of May (daily average: -61,191 km2).
353,358 km2 below 2000s average for this date.
17,802 km2 below 2010s average for this date.
138,973 km2 below 2014 value for this date.
64,867 km2 above 2012 value for this date.
3rd lowest May to-date average.
5th lowest value for the date.
7 days this year (4.7% year-to-date) have recorded the lowest daily area.
18 days (12.08%) have recorded the second lowest.
28 days (18.79%) have recorded the third lowest.
53 days in total (35.57%) have been among the lowest three on record.
Title: Re: 2015 sea ice area and extent data
Post by: BornFromTheVoid on May 31, 2015, 04:38:01 PM
Update for the week to May 30th

The current 5 day mean is on 11,844,200km2 while the 1 day extent is at 11,758,000km2.
The daily anomaly (compared to 81-10) is at -927,650km2, an increase from -750,430km2 last week. The anomaly compared to the 07, 11 and 12 average is at -440,200km2, an increase from -337,470km2 last week. We're currently lowest on record, the same as last week.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FTSXRq1Q.png&hash=1ab166939ab0d58e31c6e062a1e2af44)

The average daily change over the last 7 days was -61.4k/day, compared to the long term average of -39.9k/day, and the 07, 11 and 12 average of -46.7k/day.
The average long term change over the next week is -60.1k/day, with the 07, 11, and 12 average being -65.3k/day.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FfysMhoP.png&hash=21e02ef9ce6eff3b14d36df11df6092f)

The loss so far this May is the 8th largest on record. To achieve the largest monthly drop, a daily loss of at least 469.8k/day is required, while the smallest drop requires an increase more than 830.4k/day and an average drop requires an increase of 205.8k/day.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FWdc9cRZ.png&hash=c8699c7f02a9d21871ef1d00b7bbef91)
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on June 01, 2015, 05:06:55 PM
Tomorrow CT will drop a near century, followed by a serious uptick. Cause are Beaufort and Chukchi.

Mon       10.136581
Tue -96.7 10.039838
Wed +32.2 10.072073

Data for the first of June drop will come in tomorrow. Expect at least one century down and not to be published by CT until Thursday.

Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on June 02, 2015, 06:01:47 PM
First of June data are in and not unexpected a double century for NSIDC extent (-201.5k).

The June ice masks filter out  lots of false ice (mostly coastal). Regionally the regions St. Lawrence, Okhotsk and "other" combined contribute over -170k to the drop. Which may be some indication how much the masks have caused.

The attached image is probably telling a clearer story.
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on June 03, 2015, 02:07:19 PM
ADS-NIPR Extent:
10,800,117 km2 (02 June)
Down 3,141,943 km2 (22.54%) from 2015 maximum of 13,942,060 km2 on 15 February.
7,622,662 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Down 45,668 km2 from previous day.
Down 381,926 km2 over past seven days (daily average: -54,561 km2).
Down 78,454 km2 for the month of June (daily average: -39,227 km2).
780,101 km2 below 2000s average for this date.
389,755 km2 below 2010s average for this date.
461,791 km2 below 2014 value for this date.
587,856 km2 below 2012 value for this date.
Lowest June to-date average.
Lowest value for the date.
56 days this year (36.6% year-to-date) have recorded the lowest daily extent.
31 days (20.26%) have recorded the second lowest.
27 days (17.65%) have recorded the third lowest.
114 days (74.51%) in total have been among the three lowest on record.


CT Area:
10,072,692 km2 (02 June [Day 0.4164])
Down 3,201,863 km2 (24.12%) from 2015 maximum of 13,274,555 km2 on 17 February [Day 0.1288].
7,838,682 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Up 31,702 km2 from previous day.
Down 259,708 km2 over past seven days (daily average: -37,101 km2).
Down 63,889 km2 for the month of June (daily average: -31,944 km2).
282,427 km2 below 2000s average for this date.
818 km2 below 2010s average for this date.
88,991 km2 above 2014 value for this date.
194,306 km2 above 2012 value for this date.
5th lowest June to-date average.
8th lowest value for the date.
7 days this year (4.58% year-to-date) have recorded the lowest daily area.
18 days (11.76%) have recorded the second lowest.
28 days (18.3%) have recorded the third lowest.
53 days in total (34.64%) have been among the lowest three on record.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on June 03, 2015, 04:44:23 PM
Based on today's NSIDC sea ice concentration data, I calculate the following CT changes:

Wed       10.072692
Thu -80.8  9.991925
Fri -161.5  9.830429


Thursday drop is inflated by the first-of-the-month effect. The big drop in Friday is genuine and helped by a -80k drop in the CAB.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on June 05, 2015, 09:44:28 AM
Before presenting another AMSR2 sea ice thickness sequence, let me remind:

Quote
This product is an essentially experimental and research product. This product has the effectiveness in the relative dry freezing seasons such as autumn, winter and spring (September – May), but cannot provide the accurate sea ice thickness in melting wet season (June - August)

more here (https://ads.nipr.ac.jp/vishop/vishop-extent.html?N)

With that in mind the melting area has now reached the extents of 2013 and 2014, especially by large scale melting in Kara and adjacent regions.
Thickness does show faulty (very) high thickness values in places. I have the impression that these are also associated with melting and or open water. Not a nice way to err, but see the quote above.

(the animation show the thickness/melting from Descending orbits. I am looking at possibilities to integrate the Ascending maps as well)
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on June 05, 2015, 04:14:00 PM
CT is late again. When they update, I expect the following changes:

Wed       10.072692
Thu -80.8  9.991925
Fri -161.5  9.830403
Sat -18.8  9.811610
Sun -104.5  9.707101


Kara area is dropping from a cliff.
Title: Re: 2015 sea ice area and extent data
Post by: Stephen on June 06, 2015, 02:43:50 AM
CT is late again. When they update, I expect the following changes:

Wed       10.072692
Thu -80.8  9.991925
Fri -161.5  9.830403
Sat -18.8  9.811610
Sun -104.5  9.707101


Kara area is dropping from a cliff.

So, after Sunday, we should see lowest ever CT area for the date ( or equal to )
Title: Re: 2015 sea ice area and extent data
Post by: DavidR on June 06, 2015, 03:11:26 AM
CT is late again. When they update, I expect the following changes:

Wed       10.072692
Thu -80.8  9.991925
Fri -161.5  9.830403
Sat -18.8  9.811610
Sun -104.5  9.707101


Kara area is dropping from a cliff.

So, after Sunday, we should see lowest ever CT area for the date ( or equal to )
According to  my figures this will only  put the 2015 CT Area about 5th lowest behind 2008, 2010, 2011, and 2014; although there is  less than 100 K km^2 between the five of them.
Title: Re: 2015 sea ice area and extent data
Post by: jdallen on June 06, 2015, 09:10:54 AM
CT is late again. When they update, I expect the following changes:

Wed       10.072692
Thu -80.8  9.991925
Fri -161.5  9.830403
Sat -18.8  9.811610
Sun -104.5  9.707101


Kara area is dropping from a cliff.

So, after Sunday, we should see lowest ever CT area for the date ( or equal to )
Yep.  About that.
Title: Re: 2015 sea ice area and extent data
Post by: DavidR on June 06, 2015, 03:58:32 PM
CT is late again. When they update, I expect the following changes:

Wed       10.072692
Thu -80.8  9.991925
Fri -161.5  9.830403
Sat -18.8  9.811610
Sun -104.5  9.707101


Kara area is dropping from a cliff.

So, after Sunday, we should see lowest ever CT area for the date ( or equal to )
Yep.  About that.
Well Cryosphere data has been updated but they seem to  have forgotten Thursday. It's a good thing we have Wipneus to tell us what  is really  going on.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on June 06, 2015, 05:17:48 PM

Well Cryosphere data has been updated but they seem to  have forgotten Thursday. It's a good thing we have Wipneus to tell us what  is really  going on.

Yup, correct for the "values" column but the "normal's" are just pasted in and now not aligned anymore and the "anomalies" column is incorrect. 
Here is my version with today's NSIDC sea ice concentration data:

Sat       9.811351
Sun -104.6  9.706756
Mon -106.7  9.600101

The "torch" seems to be now in the Canadian Archipelago and in the CAB around the pole hole.
Title: Re: 2015 sea ice area and extent data
Post by: Siffy on June 06, 2015, 06:03:23 PM

Well Cryosphere data has been updated but they seem to  have forgotten Thursday. It's a good thing we have Wipneus to tell us what  is really  going on.

Yup, correct for the "values" column but the "normal's" are just pasted in and now not aligned anymore and the "anomalies" column is incorrect. 
Here is my version with today's NSIDC sea ice concentration data:

Sat       9.811351
Sun -104.6  9.706756
Mon -106.7  9.600101

The "torch" seems to be now in the Canadian Archipelago and in the CAB around the pole hole.

Hmm, what is the numerical day value for Sunday and monday using the CT data set? 155 and 156?
Title: Re: 2015 sea ice area and extent data
Post by: plg on June 06, 2015, 07:42:37 PM
...
Yup, correct for the "values" column but the "normal's" are just pasted in and now not aligned anymore and the "anomalies" column is incorrect. 
...
I have long been curious about the three columns in CT data, your comment seems to imply they should be labelled "anomaly", "value" and "normal"?

I have tried to find explanation for the file but so far no luck. Overall it appears that [anomaly = value - normal] with some jitter, but that does not explain what the "normal" value means.

Do you have some link to an explanation of the format? TIA.
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on June 06, 2015, 11:47:19 PM
CT is late again. When they update, I expect the following changes:

Wed       10.072692
Thu -80.8  9.991925
Fri -161.5  9.830403
Sat -18.8  9.811610
Sun -104.5  9.707101


Kara area is dropping from a cliff.

So, after Sunday, we should see lowest ever CT area for the date ( or equal to )
Not with those numbers from Wipneus. The most recent CT data--for Day 0.4247--leave 2015 in 8th place behind 2010 (in 1st), followed by 2011, 2014, 2008, 2012, 2007, and 2006. And some pretty remarkable things would have to happen to reach and maintain first place: Day 0.4247 saw the start of a 14-day period in 2012 in which area dropped by just under two million km2, maintaining an average daily drop of greater than 142k (the span saw 10 century drops, which included three double centuries).
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on June 07, 2015, 04:19:43 PM
From today's NSIDC sea ice concentration data, I calculate the following updates to CT-area:

Sat       9.811351
Sun -104.6  9.706756
Mon -106.6  9.600135
Tue -136.2  9.463930


A massive drop of SIA in Laptev (-82k) and a slightly smaller one in the CAB (-50k) are the cause.

It looks that the first CT-area's drop has finally started.
Title: Re: 2015 sea ice area and extent data
Post by: DavidR on June 07, 2015, 04:41:47 PM
From today's NSIDC sea ice concentration data, I calculate the following updates to CT-area:

Sat       9.811351
Sun -104.6  9.706756
Mon -106.6  9.600135
Tue -136.2  9.463930


A massive drop of SIA in Laptev (-82k) and a slightly smaller one in the CAB (-50k) are the cause.

It looks that the first CT-area's drop has finally started.
And that does seem to take us in to  record low territory  for Area!!
Title: Re: 2015 sea ice area and extent data
Post by: Phil. on June 07, 2015, 04:46:30 PM
...
Yup, correct for the "values" column but the "normal's" are just pasted in and now not aligned anymore and the "anomalies" column is incorrect. 
...
I have long been curious about the three columns in CT data, your comment seems to imply they should be labelled "anomaly", "value" and "normal"?

I have tried to find explanation for the file but so far no luck. Overall it appears that [anomaly = value - normal] with some jitter, but that does not explain what the "normal" value means.

Do you have some link to an explanation of the format? TIA.

The 'normal' value is the average over the period 1979-2008.
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on June 07, 2015, 05:05:56 PM
From today's NSIDC sea ice concentration data, I calculate the following updates to CT-area:

Sat       9.811351
Sun -104.6  9.706756
Mon -106.6  9.600135
Tue -136.2  9.463930


A massive drop of SIA in Laptev (-82k) and a slightly smaller one in the CAB (-50k) are the cause.

It looks that the first CT-area's drop has finally started.
And that does seem to take us in to  record low territory  for Area!!


Well, that would be 2nd place by Tuesday (day 0.4329) behind 2010, but by only about 13k. However, as has been stated before, 2012 jumped off the cliff on 0.4329, dropping 1.872 million km2 over the next 11 days, so 2015 has some mighty big shoes to fill. (By way of comparison, 2014 decreased just 875k km2 over that same 11-day stretch--an obvious difference of about a million km2--while 2013 dropped by 1.254 million km2, and 2007 fell 1.303 million.)
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on June 07, 2015, 05:27:28 PM
...
Yup, correct for the "values" column but the "normal's" are just pasted in and now not aligned anymore and the "anomalies" column is incorrect. 
...
I have long been curious about the three columns in CT data, your comment seems to imply they should be labelled "anomaly", "value" and "normal"?

I have tried to find explanation for the file but so far no luck. Overall it appears that [anomaly = value - normal] with some jitter, but that does not explain what the "normal" value means.

Do you have some link to an explanation of the format? TIA.

I did not spot your question at first, sorry for that. The three values are graphed here:
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Farctic.atmos.uiuc.edu%2Fcryosphere%2FIMAGES%2Fseaice.recent.arctic.png&hash=5bf49d8468051293597b66bb572a2119)

As the legend says, the normals are  the means of 1979-2008, they are repeated every year in the data file.


Title: Re: 2015 sea ice area and extent data
Post by: BornFromTheVoid on June 07, 2015, 06:35:30 PM
Update for the week to June 6th

The current 5 day mean is on 11,425,200km2 while the 1 day extent is at 11,335,000km2.
The daily anomaly (compared to 81-10) is at -920,660km2, a decrease from -927,650km2 last week. The anomaly compared to the 07, 11 and 12 average is at -402,070km2, a decrease from -440,200km2 last week. We're currently lowest on record, the same as last week.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FLQMpp0J.png&hash=31a214c2d4728f79d6679737440d33cc)

The average daily change over the last 7 days was -59.9k/day, compared to the long term average of -60.1k/day, and the 07, 11 and 12 average of -65.3k/day.
The average long term change over the next week is -44.3k/day, with the 07, 11, and 12 average being -82.5k/day.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FxL09jdn.png&hash=6198ed3d85a0c63c41cb04030e6d092f)

The loss so far this June is the 15th largest on record. To achieve the largest monthly drop, a daily loss of at least 105.2k/day is required, while the smallest drop requires a loss of less than 29.0k/day and an average drop requires a loss of 54.1k/day.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FaOH0v1W.png&hash=282f5cfe56099e88973eaaf0d7a163ad)

The loss in May was the 9th largest on record, while the average monthly extent was the lowest on record.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2Fve7lhfW.png&hash=fe5715a11cc9ba7fbae79cf4150932fd)

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FKGNNzAB.png&hash=df35ee2c75addc30224fcdf096c0a768)
Title: Re: 2015 sea ice area and extent data
Post by: jdallen on June 07, 2015, 06:58:28 PM
From today's NSIDC sea ice concentration data, I calculate the following updates to CT-area:

Sat       9.811351
Sun -104.6  9.706756
Mon -106.6  9.600135
Tue -136.2  9.463930


A massive drop of SIA in Laptev (-82k) and a slightly smaller one in the CAB (-50k) are the cause.

It looks that the first CT-area's drop has finally started.
And that does seem to take us in to  record low territory  for Area!!


Well, that would be 2nd place by Tuesday (day 0.4329) behind 2010, but by only about 13k. However, as has been stated before, 2012 jumped off the cliff on 0.4329, dropping 1.872 million km2 over the next 11 days, so 2015 has some mighty big shoes to fill. (By way of comparison, 2014 decreased just 875k km2 over that same 11-day stretch--an obvious difference of about a million km2--while 2013 dropped by 1.254 million km2, and 2007 fell 1.303 million.)
Big shoes indeed. However, I think wipneus' numbers are starting to reflect the influence of all the thin, weak first year ice across the Kara, Laptev and ESS; ice which never thickened adequately during the winter.
Its currently being blasted by hot moist air streaming out of west Asia and Eastern Europe, which shows no sign of stopping.

Add the cyclone/dipole, and I think 2012 will get a run for its money.  2015 might not stay ahead in June, but will be set up with much weaker ice in July and August.  I'm pretty alarmed by the predicted weather.
Title: Re: 2015 sea ice area and extent data
Post by: Buddy on June 07, 2015, 07:06:51 PM
Central Arctic is going to get crushed this summer...... :-[
Title: Re: 2015 sea ice area and extent data
Post by: Neven on June 07, 2015, 10:45:39 PM
Well Cryosphere data has been updated but they seem to  have forgotten Thursday. It's a good thing we have Wipneus to tell us what  is really  going on.

Indeed, the jump between 4164 and 4219 still hasn't been filled in (normally the difference between two days is 0027 or 0028). Things like this is probably what caused my spreadsheet to go wrong in the past, as I never look at the 'dates'.
Title: Re: 2015 sea ice area and extent data
Post by: plg on June 08, 2015, 06:16:40 AM
...
The 'normal' value is the average over the period 1979-2008.

...
As the legend says, the normals are  the means of 1979-2008, they are repeated every year in the data file.

Thanks, very helpful.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on June 08, 2015, 04:25:49 PM
From today's NSIDC sea ice concentration data I expect CT to report the following area changes:

Sun       9.707218
Mon -106.6  9.600597
Tue -136.1  9.464449
Wed -63.5  9.400


In case you wondered: ESS contributes -43k to the Wednesday number.
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on June 09, 2015, 01:23:21 PM
ADS-NIPR Extent:
10,590,546 km2 (08 June)
Down 3,351,514 km2 (24.04%) from 2015 maximum of 13,942,060 km2 on 15 February.
7,413,091 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Up 1,662 km2 from previous day.
Down 255,239 km2 over past seven days (daily average: -36,463 km2).
Down 288,025 km2 for the month of June (daily average: -36,003 km2).
713,374 km2 below 2000s average for this date.
254,089 km2 below 2010s average for this date.
404,137 km2 below 2014 value for this date.
254,202 km2 below 2012 value for this date.
Lowest June to-date average.
Lowest value for the date.
62 days this year (38.99% year-to-date) have recorded the lowest daily extent.
31 days (19.5%) have recorded the second lowest.
27 days (16.98%) have recorded the third lowest.
120 days (75.47%) in total have been among the three lowest on record.


CT Area:
9,463,663 km2 (08 June [Day 0.4329])
Down 3,810,892 km2 (28.71%) from 2015 maximum of 13,274,555 km2 on 17 February [Day 0.1288].
7,229,654 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Down 136,745 km2 from previous day.
Down 577,327 km2 over past seven days (daily average: -82,475 km2).
Down 672,917 km2 for the month of June (daily average: -84,115 km2).
449,062 km2 below 2000s average for this date.
96,380 km2 below 2010s average for this date.
147,139 km2 below 2014 value for this date.
50,195 km2 below 2012 value for this date.
7th lowest June to-date average.
2nd lowest value for the date.
7 days this year (4.4% year-to-date) have recorded the lowest daily area.
19 days (11.95%) have recorded the second lowest.
28 days (17.61%) have recorded the third lowest.
54 days in total (33.96%) have been among the lowest three on record.

NOTE: for those of you keeping track, the CT SIA number for Day 0.4192 has been restored: 10.0149279




Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on June 09, 2015, 06:38:01 PM
From today's NSIDC sea ice concentration data I expect CT to report the following area changes:

Tue       9.463663
Wed -63.5  9.400168
Thu -11.5  9.388671

For Thursday, just a small decline (which would have been a small uptick without the -15k drop of lake ice).
The increases are in CAB, Hudson, Laptev, and Beaufort. Declines in Baffin, Kara and ESS.
 
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on June 10, 2015, 04:23:24 PM
From today's NSIDC sea ice concentration data I expect CT to report another quiet day:

Wed       9.400280
Thu -11.5  9.388799
Fri -16.1  9.372721


Friday: biggest uptick ESS (+26.3k) and biggest drop Barents (-19.7k).
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on June 11, 2015, 04:16:57 PM
From today's NSIDC sea ice concentration data I expect CT to report another not so exiting daily change:

Wed       9.400280
Thu -11.5  9.388799
Fri -16.1  9.372733
Sat -29.6  9.343161


Highlights of the Saturday change are a -49k5 drop in Kara, nearly compensated by an uptick in the CAB of +42k2.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on June 12, 2015, 05:09:30 PM
From today's NSIDC sea ice concentration data I expect CT to report a near century on Sunday:

Thu       9.388636
Fri -16.1  9.372570
Sat -29.5  9.343038
Sun -98.8  9.244221


That is with the help of lake ice (-17k4), regions with high losses are Kara (-46k), CAA (-28k9) and Beaufort (-20k8). Laptev increased by +17k6.

NSIDC extent saw an uptick today (+64k), lots of false coastal ice in the Pacific.
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on June 13, 2015, 03:40:01 PM
ADS-NIPR Extent:
10,457,859 km2 (12 June)
Down 3,484,201 km2 (24.99%) from 2015 maximum of 13,942,060 km2 on 15 February.
7,280,404 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Down 47,973 km2 from previous day.
Down 159,768 km2 over past seven days (daily average: -22,824 km2).
Down 420,712 km2 for the month of June (daily average: -35,059 km2).
666,864 km2 below 2000s average for this date.
124,877 km2 below 2010s average for this date.
327,758 km2 below 2014 value for this date.
115,672 km2 above 2012 value for this date.
Lowest June to-date average.
3rd lowest value for the date.
64 days this year (39.26% year-to-date) have recorded the lowest daily extent.
32 days (19.63%) have recorded the second lowest.
28 days (17.18%) have recorded the third lowest.
124 days (76.07%) in total have been among the three lowest on record.


CT Area:
9,342,906 km2 (12 June [Day 0.4438])
Down 3,931,649 km2 (29.62%) from 2015 maximum of 13,274,555 km2 on 17 February [Day 0.1288].
7,108,897 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Down 29,539 km2 from previous day.
Down 468,445 km2 over past seven days (daily average: -66,921 km2).
Down 793,675 km2 for the month of June (daily average: -66,140 km2).
329,323 km2 below 2000s average for this date.
148,335 km2 above 2010s average for this date.
18 km2 above 2014 value for this date.
658,170 km2 above 2012 value for this date.
7th lowest June to-date average.
8th lowest value for the date.
7 days this year (4.29% year-to-date) have recorded the lowest daily area.
19 days (11.66%) have recorded the second lowest.
28 days (17.18%) have recorded the third lowest.
54 days in total (33.13%) have been among the lowest three on record.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on June 13, 2015, 04:56:30 PM
And on Monday CT-area will accelerate further:

Sat       9.342906
Sun -93.0  9.249906
Mon -143.4  9.106457

(CAB -55k, Barents -29k, CAA -28k)
Title: Re: 2015 sea ice area and extent data
Post by: wanderer on June 13, 2015, 05:15:58 PM
And on Monday CT-area will accelerate further:

Sat       9.342906
Sun -93.0  9.249906
Mon -143.4  9.106457

(CAB -55k, Barents -29k, CAA -28k)

Seems like the cliff is finally there!
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on June 14, 2015, 03:04:39 PM
And on Monday CT-area will accelerate further:

Sat       9.342906
Sun -93.0  9.249906
Mon -143.4  9.106457

(CAB -55k, Barents -29k, CAA -28k)

And that would leave 2015 in 8th place behind (in order) 2012 (by about 700k), 2010, 2007, 2011, 2006, 2014, and 2008. IOW, in the most recent ten year span, only 2013 and 2009 have been higher for the date.
Title: Re: 2015 sea ice area and extent data
Post by: Nick_Naylor on June 14, 2015, 03:28:35 PM
And that would leave 2015 in 8th place behind (in order) 2012 (by about 700k), 2010, 2007, 2011, 2006, 2014, and 2008. IOW, in the most recent ten year span, only 2013 and 2009 have been higher for the date.

Hycom shows a big area of thin ice that looks destined to fail soon, but then again I don't know how to reconcile Hycom's version of the ice conditions with PIOMAS, which still shows 2015 with about 5% more ice than 2014:
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2F&hash=35d7d5d7526c9897dfb55501e320295a)
Title: Re: 2015 sea ice area and extent data
Post by: Buddy on June 14, 2015, 03:45:28 PM
I'll stick my neck out a little further after looking at the two views (2015 vs 2014) you just posted.

1)  Look at the MYI "strip" north of the Canadian Archipelago and Greenland north coast.  The MYI in 2015 if NOTICEABLY thinner (especially the north Greenland coast).  It is NOT due to warm air temperatures in Greenland this year....it is the warmer water.

2)  Look at the Chukchi Sea and the Arctic north of the Chukchi Sea (the area you pointed out).  If you look at the COMBINED AREA of (a) no ice PLUS (b) thin ice.....the area this year is SIGNIFICANTLY greater than the combined area last year.  A BIG DROPOFF could be looming in coming weeks.

3)  Again....looking at the combined area of no ice + thin ice......the area along the Russian side of the Arctic is significantly weaker than last year....combined with warmer waters intruding further into the Arctic Ocean this year compared to last year.

I think we could indeed set a new record low of extent this coming September......yes lower than 2012.  Definitely NOT rooting for it....but everything is "lining up":

a)  snow cover is gone
b)  significant weak areas all around the Arctic that are "set up" to melt out
c)  warm anomalies around the Arctic

Not good.......
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on June 14, 2015, 06:01:18 PM
My estimate for CT-area gives another century on Tuesday.

Sun       9.250292
Mon -143.5  9.106802
Tue -119.3  8.987481


For Tuesday Chukchi (-32k), CAA (-30k), ESS (-20k) and Laptev (-16k) declined most. The CAB sings out of tune with a +25k uptick.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on June 15, 2015, 10:29:52 AM
Keeping an eye on the ADS-NIPR (Jaxa) AMSR2 sea ice thickness/melting map, melting area has greatly increased in the last few day. With today's map the total area in  melting has risen above 2013 and 2014 levels. Area's affected include the Canadian Archipelago, the "Barents Bite" and today an explosion on the Pacific side (Beaufort, Chukchi, ESS and bordering part of the CAB).
In area only the CAA is making a clear nosedive, perhaps in a few days other regions will follow?

Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on June 15, 2015, 04:49:09 PM
Well, area as calculated from NSIDC sea ice concentration certainly sees it that way. From that I expect a fat triple century next Wednesday:

Mon       9.106157
Tue -119.6  8.986600
Wed -340.0  8.646564

The regions on the Pacific side that I mentioned in the previous post are responsible: CAB(-132k), ESS(-48k), Beaufort (-30k) and Chukchi (-27k). Add an active Hudson (-57k) and Kara (-21k)  to secure the third century.
Title: Re: 2015 sea ice area and extent data
Post by: oren on June 15, 2015, 05:14:42 PM
Well, area as calculated from NSIDC sea ice concentration certainly sees it that way. From that I expect a fat triple century next Wednesday:

Mon       9.106157
Tue -119.6  8.986600
Wed -340.0  8.646564

The regions on the Pacific side that I mentioned in the previous post are responsible: CAB(-132k), ESS(-48k), Beaufort (-30k) and Chukchi (-27k). Add an active Hudson (-57k) and Kara (-21k)  to secure the third century.

Fat triple century indeed. Impressive.
Title: Re: 2015 sea ice area and extent data
Post by: Neven on June 15, 2015, 05:47:17 PM
A quick glance at my CT SIA spreadsheet tells me a drop this big (300K+) hasn't happened since 2008. Impressive indeed.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on June 15, 2015, 05:52:32 PM
As this animation of the NSIDC sea ice concentration shows it is not only the Pacific side, but also a broad range in what has been called the "Barents Bite".
Title: Re: 2015 sea ice area and extent data
Post by: BornFromTheVoid on June 15, 2015, 06:55:54 PM
Update for the week to June 13th

The current 5 day mean is on 11,175,800km2 while the 1 day extent is at 11,076,000km2.
The daily anomaly (compared to 81-10) is at -859,890km2, a decrease from -920,660km2 last week. The anomaly compared to the 07, 11 and 12 average is at -73,930km2, a decrease from -402,070km2 last week. We're currently 4th lowest on record, down from lowest last week.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2F3QWWb2Y.png&hash=92e2e276b7d5e1eac01c2a6f12f20a33)

The average daily change over the last 7 days was -35.6k/day, compared to the long term average of -44.3k/day, and the 07, 11 and 12 average of -82.5k/day.
The average long term change over the next week is -52.6k/day, with the 07, 11, and 12 average being -81.2k/day.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FKjsMXbr.png&hash=480cc11bf8e8ddc34e6cb8484a0ebc24)

The loss so far this June is the 18th smallest on record. To achieve the largest monthly drop, a daily loss of at least 133.8k/day is required, while the smallest drop requires a loss of less than 26.2k/day and an average drop requires a loss of 61.7k/day.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FxaGBabL.png&hash=37ec8e6ece338b9e13d7e3282a13a5f3)
Title: Re: 2015 sea ice area and extent data
Post by: Tor Bejnar on June 15, 2015, 07:27:01 PM
Continued thanks BFTV for these summary updates.

I note that the 'minimum extent loss' line is made up of mostly small segments of slow loss  whereas the 'maximum extent loss' line is dominated by much larger segments of high loss; I'll hazard a guess that post-2006 years dominate the 'maximum extent loss' line.  (I recall you identified some of the years for some of the record-holding years.)

I'm sure this is due to the changing climate.  :D
Title: Re: 2015 sea ice area and extent data
Post by: Stephen on June 16, 2015, 04:44:08 AM
Well, area as calculated from NSIDC sea ice concentration certainly sees it that way. From that I expect a fat triple century next Wednesday:

Mon       9.106157
Tue -119.6  8.986600
Wed -340.0  8.646564

The regions on the Pacific side that I mentioned in the previous post are responsible: CAB(-132k), ESS(-48k), Beaufort (-30k) and Chukchi (-27k). Add an active Hudson (-57k) and Kara (-21k)  to secure the third century.

Thanks for you work Wipneus but when you say next Wednesday, do you mean the 17th or the 24th?

Seinfield (https://www.youtube.com/watch?v=71nvWNAvZfs) did an episode on the difference. 

Maybe include day number (of the year)? then it would be easier for dummies like me.  CT uses day number.
Title: Re: 2015 sea ice area and extent data
Post by: jdallen on June 16, 2015, 05:16:10 AM
Well, area as calculated from NSIDC sea ice concentration certainly sees it that way. From that I expect a fat triple century next Wednesday:

Mon       9.106157
Tue -119.6  8.986600
Wed -340.0  8.646564

The regions on the Pacific side that I mentioned in the previous post are responsible: CAB(-132k), ESS(-48k), Beaufort (-30k) and Chukchi (-27k). Add an active Hudson (-57k) and Kara (-21k)  to secure the third century.

Thanks for you work Wipneus but when you say next Wednesday, do you mean the 17th or the 24th?

Seinfield (https://www.youtube.com/watch?v=71nvWNAvZfs) did an episode on the difference. 

Maybe include day number (of the year)? then it would be easier for dummies like me.  CT uses day number.
Pretty clear to me he's talking about the 17th.
Title: Re: 2015 sea ice area and extent data
Post by: DavidR on June 16, 2015, 05:40:59 AM
Well, area as calculated from NSIDC sea ice concentration certainly sees it that way. From that I expect a fat triple century next Wednesday:

Mon       9.106157
Tue -119.6  8.986600
Wed -340.0  8.646564

The regions on the Pacific side that I mentioned in the previous post are responsible: CAB(-132k), ESS(-48k), Beaufort (-30k) and Chukchi (-27k). Add an active Hudson (-57k) and Kara (-21k)  to secure the third century.

Thanks for you work Wipneus but when you say next Wednesday, do you mean the 17th or the 24th?

Seinfield (https://www.youtube.com/watch?v=71nvWNAvZfs) did an episode on the difference. 

Maybe include day number (of the year)? then it would be easier for dummies like me.  CT uses day number.
Stephen,
Wipneus calculates the area from the NSIDC data that CT uses in their calculations.  CT release their data 2 days, (or more) after NSIDC releases it. He has got the calculation so accurate that there is rarely even 1000 km^2 variation between his calculations and theirs. Also  note that  the day given is the day CT releases the data the measurements would have been taken on Sunday  and released as extent data on Monday. 
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on June 16, 2015, 07:57:38 AM
Right. Apologies for the ambiguous (if not wrong) "next" Wednesday. I will try to be more clear about this in the future.
Title: Re: 2015 sea ice area and extent data
Post by: oren on June 16, 2015, 08:07:22 AM
It's funny. Why don't CT publish their results 2 days earlier? If Wipneus can, so can they...
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on June 16, 2015, 08:15:31 AM
Updated the AMSR2  thickness/melting (from ADS-NIPR Jaxa) animation.

Again the melting area increased in several regions. Hudson and ESS most clearly. Melting crossed the "pole hole".

Jaxa and UH AMSR2 area have still not responded to the sudden increase in melting (as defined by these maps). You can see this for example here (https://sites.google.com/site/arctischepinguin/home/amsr2/grf/amsr2-area-all-cmpare.png)
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on June 16, 2015, 02:50:44 PM
A quick glance at my CT SIA spreadsheet tells me a drop this big (300K+) hasn't happened since 2008. Impressive indeed.
That's correct. For the record, there were two monster single-day drops that year: 396k in late April, and 437k in early May. The largest one-day decrease since then was 287k in the first week of June last year.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on June 16, 2015, 04:31:05 PM
From today's NSIDC sea ice concentration data update, I calculate the CT-area updates of the coming few day's:

Mon       9.106157
Tue -119.6  8.986600
Wed -340.2  8.646372
Thu -71.6  8.574772

After Wednesday the drop on Thursday will be much smaller. Regarding the small extent uptick of (NSIDC calculation +4k6), the melting effect is still very much active.
Regional the fastest area declines are in Hudson (-36k), Chukchi(-21k) and CAB (-19k).
Title: Re: 2015 sea ice area and extent data
Post by: Yuha on June 16, 2015, 04:40:35 PM
A quick glance at my CT SIA spreadsheet tells me a drop this big (300K+) hasn't happened since 2008. Impressive indeed.
That's correct. For the record, there were two monster single-day drops that year: 396k in late April, and 437k in early May. The largest one-day decrease since then was 287k in the first week of June last year.

The triple century follows two centuries (-143.5k and -119.6k) with a combined loss of over 600k in three days. How rare is that?
Title: Re: 2015 sea ice area and extent data
Post by: Bruce Steele on June 16, 2015, 05:27:41 PM
Wipneus, Thank you for the beautiful graphics. The retreat of the ice edge and the two fingers it forms on either side of the Herald Shoal ( Chukchi Sea ) are forming in the animation above. The retreat is a full month earlier than in 92-94 as documented in the Martin + Drucker '97 paper on Taylor columns.

  http://polar.ocean.washington.edu/taylor/chukchi_shoals.html (http://polar.ocean.washington.edu/taylor/chukchi_shoals.html)

Title: Re: 2015 sea ice area and extent data
Post by: Tor Bejnar on June 16, 2015, 05:46:51 PM
Slater Probabilistic Ice Extent (SPIE) (http://cires1.colorado.edu/~aslater/SEAICE/) 50-day projection is sure responding to something that is happening 'now'!

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fcires1.colorado.edu%2F%7Easlater%2FSEAICE%2Ffcst_apr_oct.gif&hash=066f9d1df8dfb7a6ec303e553a47446b)
Title: Re: 2015 sea ice area and extent data
Post by: Lord M Vader on June 16, 2015, 06:03:01 PM
Tor Bejnar: not a too dramatic pic from Slater if you ask me. From August an until the minimum the Arctic loses roughly 2 million km2. That would yield a minima about 4,5-5 million km2. Of course, I would like to know earlier years minima/extent for the same time period.

Best, LMV
Title: Re: 2015 sea ice area and extent data
Post by: Lord M Vader on June 16, 2015, 06:18:24 PM
Tor Bejnar: I would like to add the following link to get a better picture of Slaters historical forecasts versus observations: http://cires1.colorado.edu/~aslater/SEAICE/Slater_AGU_2013_poster.pdf (http://cires1.colorado.edu/~aslater/SEAICE/Slater_AGU_2013_poster.pdf)

//LMV
Title: Re: 2015 sea ice area and extent data
Post by: Lord M Vader on June 16, 2015, 06:30:53 PM
What I find most surprising with Slaters pic is the very high probability for ice in the ESS by the beginning of August as well as the rather low likelihood for ice at the North Pole.

//LMV
Title: Re: 2015 sea ice area and extent data
Post by: jai mitchell on June 16, 2015, 06:37:25 PM
The 2012 August 7th value for Charctic was 5.767 this is about 4 days ahead of the Slater chart for that same day, however, the rate of decline is more and it seems that it would catch up and surpass the 2012 minimum without too much difficulty.  It is not clear to me what would drive the rapid decrease?  Would it be a function of current ice thickness patterns?   or possibly a greater rate of ice export?  wave effects? all the above?

amazing that they have been so accurate up to this point, thanks for the poster LMV.
Title: Re: 2015 sea ice area and extent data
Post by: seaicesailor on June 16, 2015, 10:15:27 PM
What I find most surprising with Slaters pic is the very high probability for ice in the ESS by the beginning of August as well as the rather low likelihood for ice at the North Pole.

//LMV

From the discussion in the "melting season" thread, I gather that the Eurasian coast, including Laptev, has been cold and started melting late, but ice may be thin now, due to record strength of the Transpolar drift this winter. Seems very complicated to predict the outcome there.
Title: Re: 2015 sea ice area and extent data
Post by: AySz88 on June 17, 2015, 08:15:28 AM
Tor Bejnar: not a too dramatic pic from Slater if you ask me. From August an until the minimum the Arctic loses roughly 2 million km2. That would yield a minima about 4,5-5 million km2. Of course, I would like to know earlier years minima/extent for the same time period.

Best, LMV

By my reading, the oddity being pointed out is not the forecast per se, but literally the fact that it has suddenly shifted down.  I wonder whether that rate is "real" or if it is due to some unexpected development in the sea ice concentration data that came in during the last few days. In the latter case, that would seem to suggest that the last few days have changed the game a bit, at least from the perspective of Slater's forecasting model.  (But on the other hand, that drop may have been waiting in the wings all along, say if we used the same method to get forecasts of days 51-57 from last week's data. Hard to tell....)

Edited to add...

What I find most surprising with Slaters pic is the very high probability for ice in the ESS by the beginning of August as well as the rather low likelihood for ice at the North Pole.

//LMV

I'd note that, as far as I can tell, the probability of survival is calculated solely from the current "concentration" in the grid cell (possibly melt pond contaminated) and the current date - the model is ignorant of where the grid cell is located.  Also the model doesn't seem that skillful in mid June....
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on June 17, 2015, 01:28:18 PM
ADS-NIPR Extent:
10,207,482 km2 (16 June)
Down 3,734,578 km2 (26.79%) from 2015 maximum of 13,942,060 km2 on 15 February.
7,030,027 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Down 76,315 km2 from previous day.
Down 380,736 km2 over past seven days (daily average: -54,391 km2).
Down 671,089 km2 for the month of June (daily average: -41,943 km2).
684,926 km2 below 2000s average for this date.
94,984 km2 below 2010s average for this date.
295,452 km2 below 2014 value for this date.
145,232 km2 above 2012 value for this date.
Lowest June to-date average.
3rd lowest value for the date.
64 days this year (38.32% year-to-date) have recorded the lowest daily extent.
32 days (19.16%) have recorded the second lowest.
32 days (19.16%) have recorded the third lowest.
128 days (76.65%) in total have been among the three lowest on record.


CT Area:
8,646,584 km2 (16 June [Day 0.4548])
Down 4,627,972 km2 (34.86%) from 2015 maximum of 13,274,555 km2 on 17 February [Day 0.1288].
6,412,574 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Down 339,857 km2 from previous day.
Down 753,696 km2 over past seven days (daily average: -107,671 km2).
Down 1,489,997 km2 for the month of June (daily average: -93,125 km2).
651,227 km2 below 2000s average for this date.
26,221 km2 below 2010s average for this date.
305,494 km2 below 2014 value for this date.
616,678 km2 above 2012 value for this date.
7th lowest June to-date average.
3rd lowest value for the date.
7 days this year (4.19% year-to-date) have recorded the lowest daily area.
19 days (11.38%) have recorded the second lowest.
29 days (17.37%) have recorded the third lowest.
55 days in total (32.93%) have been among the lowest three on record.
Title: Re: 2015 sea ice area and extent data
Post by: Blizzard_of_Oz on June 17, 2015, 02:38:59 PM
What I find most surprising with Slaters pic is the very high probability for ice in the ESS by the beginning of August as well as the rather low likelihood for ice at the North Pole.

Indeed the forecasts from the last few days are a surprising turn of events. The SPIE is a statistical forecast with zero memory, so let's see what happens in the next week or so. If it is in error now, it could 'self-correct' - it has done so in the past (e.g. 2010). In any case, it makes me think there are some interesting events ahead.

Also, for some info on prior performance, scroll down to 'Regional Contributions' and Figures 9 & 10
http://www.arcus.org/sipn/sea-ice-outlook/2014/post-season (http://www.arcus.org/sipn/sea-ice-outlook/2014/post-season)
(but I wouldn't judge relative skill of forecast systems on the basis of one year/event)
Title: Re: 2015 sea ice area and extent data
Post by: Nightvid Cole on June 17, 2015, 04:16:42 PM
June 16th CT value has fallen off the June cliff!
Title: Re: 2015 sea ice area and extent data
Post by: Nick_Naylor on June 17, 2015, 04:23:14 PM
Indeed. Very impressive launch to June Swoon :)
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on June 17, 2015, 04:38:13 PM
The cliff has already paused. The CT-area numbers (calculated from today's NSIDC sea ice concentration update) for the coming two days are:

Wed       8.646584
Thu -71.7  8.574850
Fri -54.4  8.520460

OK, the last drop would have been higher without the uptick in "lake" ice (+23k7). Also the CAB went up (+27k5). The declines are in ESS , Laptev, CAA, Beaufort, Baffin and Kara (all similar ~-18k).
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on June 17, 2015, 05:29:21 PM
The cliff has already paused. The CT-area numbers (calculated from today's NSIDC sea ice concentration update) for the coming two days are:

Wed       8.646584
Thu -71.7  8.574850
Fri -54.4  8.520460

OK, the last drop would have been higher without the uptick in "lake" ice (+23k7). Also the CAB went up (+27k5). The declines are in ESS , Laptev, CAA, Beaufort, Baffin and Kara (all similar ~-18k).

Those numbers will knock CT SIA back into 5th place, and again roughly three-quarters of a million square kilometers below 2012's same-day numbers. Then again, the steepest part of 2012's cliff ended this Friday; having dropped nearly 2 million km2 in the previous two week period (where 2015 will have lost just 1.3 million), 2012's torrid pace calmed for a bit, losing just 418k over the ensuing week. IOW: 2015 should be able to do a little catching up.
Title: Re: 2015 sea ice area and extent data
Post by: Nightvid Cole on June 17, 2015, 06:07:40 PM
The cliff has already paused. The CT-area numbers (calculated from today's NSIDC sea ice concentration update) for the coming two days are:

Wed       8.646584
Thu -71.7  8.574850
Fri -54.4  8.520460

OK, the last drop would have been higher without the uptick in "lake" ice (+23k7). Also the CAB went up (+27k5). The declines are in ESS , Laptev, CAA, Beaufort, Baffin and Kara (all similar ~-18k).

I am confused. Today's NSIDC data is for yesterday (6/16). Since CT data also extends through yesterday, how can you possibly 'foretell' CT data using NDISC data if the latter does not cover more days than the former? Please explain.
Title: Re: 2015 sea ice area and extent data
Post by: Nick_Naylor on June 17, 2015, 06:23:42 PM
The CT data plots area vs. publication date rather than data acquisition date, which is three days earlier. That's how Wipneus is able to forecast so spectacularly :)
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on June 17, 2015, 06:25:04 PM
I am confused. Today's NSIDC data is for yesterday (6/16). Since CT data also extends through yesterday, how can you possibly 'foretell' CT data using NDISC data if the latter does not cover more days than the former? Please explain.

CT presents data that is 2 days behind for reasons I do not know.
Attached is a graph with the real CT-values and my calculations. Only by a shift of two days they can match.
Title: Re: 2015 sea ice area and extent data
Post by: Nightvid Cole on June 17, 2015, 06:37:51 PM
Ok, makes sense now.  :)
Title: Re: 2015 sea ice area and extent data
Post by: ChrisReynolds on June 17, 2015, 09:08:54 PM
June 16th CT value has fallen off the June cliff!

Area 'proper' as calculated by Wipneus, the closest thing we have to regional has dropped even more.

http://dosbat.blogspot.co.uk/2015/06/looking-promising.html (http://dosbat.blogspot.co.uk/2015/06/looking-promising.html)
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on June 18, 2015, 05:06:54 PM
From today's update of NSIDC sea ice concentration data, I calculate CT-area for tomorrow and the day after:

Thu       8.576599
Fri -54.5  8.522109
Sat -35.0  8.487070

Bad melting day, Saturday, especially as it includes a -21k drop in "lake ice". Upticks in CAB (+43k5 and Beaufort (+16k5). Kara, Baffin, CAA and Greenland Sea decline at rates ~ -18k.
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on June 18, 2015, 10:53:23 PM
From today's update of NSIDC sea ice concentration data, I calculate CT-area for tomorrow and the day after:

Thu       8.576599
Fri -54.5  8.522109
Sat -35.0  8.487070

Bad melting day, Saturday, especially as it includes a -21k drop in "lake ice". Upticks in CAB (+43k5 and Beaufort (+16k5). Kara, Baffin, CAA and Greenland Sea decline at rates ~ -18k.
That will knock 2015 back down to 7th place (behind 2012, 2011, 2007, 2006, 2008, and 2010), and nearly three-quarters of a million square kilometers behind 2012.

With the singular exception of the 340k drop the other day, this has been a very mild few weeks melt-wise. Will it continue this way? Or is there any mechanism by which the melt season might get even close to what was hinted at back just a month or two ago? Eight weeks ago, 2015 was 840k ahead of 2012; 2012 is now 629k ahead of 2015, a swing of nearly a million-and-a-half square kilometers. What happened?

Title: Re: 2015 sea ice area and extent data
Post by: DavidR on June 18, 2015, 11:20:06 PM
From today's update of NSIDC sea ice concentration data, I calculate CT-area for tomorrow and the day after:

Thu       8.576599
Fri -54.5  8.522109
Sat -35.0  8.487070

Bad melting day, Saturday, especially as it includes a -21k drop in "lake ice". Upticks in CAB (+43k5 and Beaufort (+16k5). Kara, Baffin, CAA and Greenland Sea decline at rates ~ -18k.
That will knock 2015 back down to 7th place (behind 2012, 2011, 2007, 2006, 2008, and 2010), and nearly three-quarters of a million square kilometers behind 2012.

With the singular exception of the 340k drop the other day, this has been a very mild few weeks melt-wise. Will it continue this way? Or is there any mechanism by which the melt season might get even close to what was hinted at back just a month or two ago? Eight weeks ago, 2015 was 840k ahead of 2012; 2012 is now 629k ahead of 2015, a swing of nearly a million-and-a-half square kilometers. What happened?

Eight weeks ago, in 2012, there was an extra 6-700 K km^2 in the north Pacific plus a much larger area of ice that was between 0.6 and 1 m  in 2012 compared to 2015. This ice has now melted out.  2012 was also much  warmer in May and June. Given the fact that early  May this year was comparatively cold the fact that  we have lost as much ice as we have this year is surprising.     
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on June 19, 2015, 04:30:36 PM
Today's NSIDC sea ice concentrate update gives these expected CT-area updates:

Fri       8.520306
Sat -35.0  8.485257
Sun -147.3  8.337985

So on Sunday again a big drop in sea ice area, while the extent is hardly changed. That is a sign of surface melting. Regions are  ESS, Laptev and CAB where this is happening (-71k, -31k and -15k).
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on June 20, 2015, 03:18:00 PM
Today's NSIDC sea ice concentrate update gives these expected CT-area updates:

Fri       8.520306
Sat -35.0  8.485257
Sun -147.3  8.337985

So on Sunday again a big drop in sea ice area, while the extent is hardly changed. That is a sign of surface melting. Regions are  ESS, Laptev and CAB where this is happening (-71k, -31k and -15k).

And that will drop SIA from its current 5th spot to 6th, behind 2012, 2011, 2010, 2006, and 2007.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on June 20, 2015, 07:21:55 PM
Based on today's NSIDC sea ice concentrate update I expect on Monday another large drop in CT-area:

Fri       8.520306
Sat -35.0  8.485257
Sun -147.3  8.337926
Mon -169.6  8.168340

With the corresponding extent drop very limited (-28k2 for NSIDC extent), we can assume this is mostly a surface melting effect. The drop is very large in the ESS (-71k1) and CAB (-43k3). "Lake ice" jumped +17k2.
Title: Re: 2015 sea ice area and extent data
Post by: Lord M Vader on June 20, 2015, 07:43:06 PM
Wipneus: what were the corresponding CTA numbers for the years ahead 2015? If possible, do you have an opportunity to put in the leaders number when you're doing those great updates? :D

Looking at ESS today is very interesting! Wipneus 3,125 km resolution of the Arctic basin shows that the ESS is breaking up at the shoreline, something I think didn't occurred until sometime in July both 2014 and 2013? Correct or?!

If current trend in the ESS continues and some more melting will be seen in the Laptev Sea, the Northern Sea Route should maybe, just maybe, open up in a narrow channel by July 15...

Best, LMV
Title: Re: 2015 sea ice area and extent data
Post by: seaicesailor on June 20, 2015, 08:06:39 PM
Wipneus: what were the corresponding CTA numbers for the years ahead 2015? If possible, do you have an opportunity to put in the leaders number when you're doing those great updates? :D

Looking at ESS today is very interesting! Wipneus 3,125 km resolution of the Arctic basin shows that the ESS is breaking up at the shoreline, something I think didn't occurred until sometime in July both 2014 and 2013? Correct or?!

If current trend in the ESS continues and some more melting will be seen in the Laptev Sea, the Northern Sea Route should maybe, just maybe, open up in a narrow channel by July 15...

Best, LMV

From MODIS today,

https://forum.arctic-sea-ice.net/index.php/topic,1149.msg54504.html#msg54504

Count Laptev Sea as well for the July crash
Title: Re: 2015 sea ice area and extent data
Post by: Lord M Vader on June 20, 2015, 08:30:22 PM
Seaicesailor: aaah, yes, I saw that nice picture :) Will be interesting to see if the July crash materializes!  8)
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on June 21, 2015, 04:53:31 PM
Based on today's NSIDC sea ice concentrate update I expect Tuesday to be a slow melt day:

Fri       8.520306
Sat -35.0  8.485257
Sun -147.3  8.337926
Mon -169.4  8.168544
Tue -48.5  8.119998

That includes a -21k drop in "lake ice". Conditions in the ESS (+69k7) and Laptev (+23k8) seem to have gone from melting to freezing somehow. Hudson (-29k4) and Baffin (-22k1) drop most (and those lakes of course).
Title: Re: 2015 sea ice area and extent data
Post by: BornFromTheVoid on June 21, 2015, 08:48:40 PM
Update for the week to June 20th

The current 5 day mean is on 10,780,600km2 while the 1 day extent is at 10,693,000km2.
The daily anomaly (compared to 81-10) is at -887,150km2, an increase from -859,890km2 last week. The anomaly compared to the 07, 11 and 12 average is at +98,467km2, an increase from -73,930km2 last week. We're currently 4th lowest on record, the same as last week.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FjbMdMTZ.png&hash=d021a4a1fc7d982b0f01345a707e309c)

The average daily change over the last 7 days was -56.5k/day, compared to the long term average of -52.6k/day, and the 07, 11 and 12 average of -81.2k/day.
The average long term change over the next week is -60.5k/day, with the 07, 11, and 12 average being -81.1k/day.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FyqeJE6W.png&hash=6f0f3fd25216c217fd467accc5482ba4)

The loss so far this June is the 18th largest on record. To achieve the largest monthly drop, a daily loss of at least 187.9k/day is required, while the smallest drop requires a loss of less than 5.1k/day and an average drop requires a loss of 65.4k/day.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FKx6mosU.png&hash=68db374cead17b6ed8b343c2acac88f4)
Title: Re: 2015 sea ice area and extent data
Post by: Buddy on June 21, 2015, 10:25:28 PM
Quote
...and an average drop requires a loss of 65.4k/day

An average drop covering what time span?

Thanks...

Title: Re: 2015 sea ice area and extent data
Post by: DavidR on June 21, 2015, 11:06:24 PM
Quote
...and an average drop requires a loss of 65.4k/day

An average drop covering what time span?

Thanks...
All rates are quoted until the end of the month ie to acheive an average drop  for the month of June. 
Recently average drop  for the remainder of the month is over 100k / day so 65.4 would remain remarkably  low.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on June 22, 2015, 04:37:15 PM
No losses on Wednesday, expected CT-area updates from today's update of NSIDC sea ice concentration data:

Fri       8.520306
Sat -35.0  8.485257
Sun -147.3  8.337926
Mon -169.4  8.168544
Tue -48.9  8.119646
Wed +0.3  8.119995

Area in ESS and CAA went up (+22k5 and 13k7), Hudson and Baffin down (-18k and -16k4).
Title: Re: 2015 sea ice area and extent data
Post by: jdallen on June 22, 2015, 05:41:23 PM
No losses on Wednesday, expected CT-area updates from today's update of NSIDC sea ice concentration data:

Fri       8.520306
Sat -35.0  8.485257
Sun -147.3  8.337926
Mon -169.4  8.168544
Tue -48.9  8.119646
Wed +0.3  8.119995

Area in ESS and CAA went up (+22k5 and 13k7), Hudson and Baffin down (-18k and -16k4).
...

Got to be melt ponds draining.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on June 22, 2015, 07:17:18 PM
For a better understanding where the area increase and decreases are coming from, I have added a color shade tot the NSIDC delta map. Pinkish is where concentration dropped more than some threshold, light bluish is where the concentration increased. For now I have set the threshold at 7%.

As before bright red and blue indicate crossing the 15% line, meaning extent increase/decrease.
Title: Re: 2015 sea ice area and extent data
Post by: ChrisReynolds on June 22, 2015, 07:26:24 PM
No losses on Wednesday, expected CT-area updates from today's update of NSIDC sea ice concentration data:

Fri       8.520306
Sat -35.0  8.485257
Sun -147.3  8.337926
Mon -169.4  8.168544
Tue -48.9  8.119646
Wed +0.3  8.119995

Area in ESS and CAA went up (+22k5 and 13k7), Hudson and Baffin down (-18k and -16k4).

That takes me up to 23 June with CT Area data, albeit 'provisional'.

So my CT Area prediction for 2015 September minimum (daily value) is:

3.0 to 3.8M km^2, central value 3.4M km^2

The hindcasts for the model are 80% successful. In the post 2007 period there were two failures, 2009 and 2012 (0.18 and 0.17 respectively below the lower bound).

This prediction encompasses 2009, 2010, 2013 and 2014. This suggests a relatively normal post 2015 minimum.

Method described here:
http://dosbat.blogspot.co.uk/2015/05/predicting-ct-area-minimum.html (http://dosbat.blogspot.co.uk/2015/05/predicting-ct-area-minimum.html)
Title: Re: 2015 sea ice area and extent data
Post by: AySz88 on June 22, 2015, 08:28:59 PM
Quote
...and an average drop requires a loss of 65.4k/day

An average drop covering what time span?

Thanks...

In case you're asking about years and not days, I think it's the average of 1981-2010 assuming its the same time period as the middle graph.
Title: Re: 2015 sea ice area and extent data
Post by: Buddy on June 22, 2015, 09:15:50 PM
Quote
In case you're asking about years and not days, I think it's the average of 1981-2010 assuming its the same time period as the middle graph.

Yes....thanks.  I asked a "sloppy" question, and was just about to clarify.

Thanks again....


Title: Re: 2015 sea ice area and extent data
Post by: seaicesailor on June 23, 2015, 01:09:03 AM
No losses on Wednesday, expected CT-area updates from today's update of NSIDC sea ice concentration data:

Fri       8.520306
Sat -35.0  8.485257
Sun -147.3  8.337926
Mon -169.4  8.168544
Tue -48.9  8.119646
Wed +0.3  8.119995

Area in ESS and CAA went up (+22k5 and 13k7), Hudson and Baffin down (-18k and -16k4).
...

Got to be melt ponds draining.

All at the same time... like somebody flushed them down?
Just teasing  ;)
Title: Re: 2015 sea ice area and extent data
Post by: Stephen on June 23, 2015, 03:56:02 AM
Looks like CT is having a little break, they haven't updated their area graph since the 18th
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on June 23, 2015, 05:18:02 PM
From today's NSIDC sea ice concentration update I calculate the following future CT-area updates:

Fri       8.520306
Sat -35.0  8.485257
Sun -147.3  8.337926
Mon -169.4  8.168544
Tue -48.9  8.119646
Wed +0.3  8.119965
Thu -92.9  8.027085

Biggest declines for Thursday are CAA (-23k), Baffin (-21k), CAB (-16k2) and Beaufort (-12k1).
In the attached delta map, pixels with larger concentration changes than 7% or colored pinkish (down) or light blue (up)

Title: Re: 2015 sea ice area and extent data
Post by: seaicesailor on June 23, 2015, 05:36:58 PM
No losses on Wednesday, expected CT-area updates from today's update of NSIDC sea ice concentration data:

Fri       8.520306
Sat -35.0  8.485257
Sun -147.3  8.337926
Mon -169.4  8.168544
Tue -48.9  8.119646
Wed +0.3  8.119995

Area in ESS and CAA went up (+22k5 and 13k7), Hudson and Baffin down (-18k and -16k4).

That takes me up to 23 June with CT Area data, albeit 'provisional'.

So my CT Area prediction for 2015 September minimum (daily value) is:

3.0 to 3.8M km^2, central value 3.4M km^2

The hindcasts for the model are 80% successful. In the post 2007 period there were two failures, 2009 and 2012 (0.18 and 0.17 respectively below the lower bound).

This prediction encompasses 2009, 2010, 2013 and 2014. This suggests a relatively normal post 2015 minimum.

Method described here:
http://dosbat.blogspot.co.uk/2015/05/predicting-ct-area-minimum.html (http://dosbat.blogspot.co.uk/2015/05/predicting-ct-area-minimum.html)

You recently wrote in your blog (post about possible crash this year) about the possibility of area going down in June (unremarkably) while June extent stalling. Compaction dropping, but still not meaning much in either direction.

So your method is purely quantitative, but still, don't you think your result has much to do with recent weather (and by recent I mean past 7 days).

A sensitivity test would consist on doing same math analysis for 15 June, or for July 1st when it comes. Just to see how your semi-statistical method converges...

Just a thought.



Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on June 23, 2015, 05:42:34 PM
ADS-NIPR Extent:
9,991,615 km2 (22 June)
Down 3,950,445 km2 (28.33%) from 2015 maximum of 13,942,060 km2 on 15 February.
6,814,160 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Down 40,059 km2 from previous day.
Down 292,182 km2 over past seven days (daily average: -41,740 km2).
Down 886,956 km2 for the month of June (daily average: -40,316 km2).
491,449 km2 below 2000s average for this date.
79,923 km2 above 2010s average for this date.
29,009 km2 above 2014 value for this date.
302,133 km2 above 2012 value for this date.
Lowest June to-date average.
5th lowest value for the date.
64 days this year (36.99% year-to-date) have recorded the lowest daily extent.
32 days (18.5%) have recorded the second lowest.
32 days (18.5%) have recorded the third lowest.
128 days (73.99%) in total have been among the three lowest on record.


CT Area:
NOTE: due to the prolonged absence of official CT sea ice area data, I've instead used Wipneus' calculated area numbers for the period from 18 June through 22 June. The official numbers will be inserted if/when available. In the meantime, thanks, Wipneus!
8,119,646 km2 (22 June [Day 0.4712])
Down 5,154,909 km2 (38.83%) from 2015 maximum of 13,274,555 km2 on 17 February [Day 0.1288].
5,885,637 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Down 48,898 km2 from previous day.
Down 866,795 km2 over past seven days (daily average: -123,828 km2).
Down 2,016,935 km2 for the month of June (daily average: -91,679 km2).
542,932 km2 below 2000s average for this date.
80,808 km2 above 2010s average for this date.
141,966 km2 below 2014 value for this date.
532,248 km2 above 2012 value for this date.
7th lowest June to-date average.
6th lowest value for the date.
7 days this year (4.05% year-to-date) have recorded the lowest daily area.
19 days (10.98%) have recorded the second lowest.
29 days (16.76%) have recorded the third lowest.
55 days in total (31.79%) have been among the lowest three on record.



Title: Re: 2015 sea ice area and extent data
Post by: jdallen on June 23, 2015, 05:44:55 PM
No losses on Wednesday, expected CT-area updates from today's update of NSIDC sea ice concentration data:

Fri       8.520306
Sat -35.0  8.485257
Sun -147.3  8.337926
Mon -169.4  8.168544
Tue -48.9  8.119646
Wed +0.3  8.119995

Area in ESS and CAA went up (+22k5 and 13k7), Hudson and Baffin down (-18k and -16k4).
...

Got to be melt ponds draining.

All at the same time... like somebody flushed them down?
Just teasing  ;)
Taken in good spirit
Title: Re: 2015 sea ice area and extent data
Post by: wanderer on June 23, 2015, 06:29:42 PM

CT Area:
8,119,646 km2 (22 June [Day 0.4712])
Down 5,154,909 km2 (38.83%) from 2015 maximum of 13,274,555 km2 on 17 February [Day 0.1288].
532,248 km2 above 2012 value for this date.

2015 is 532k above 2012.

Baffin: ~ 200k behind 2012 -> will melt
Kara: ~ 100k behind 2012 -> will melt
Barents: ~ 100-150k behind 2012 -> will melt

2012 is just a little bit ahead in Laptev and Beaufort, other regions are almost the same.

So... I expect more losses soon, nothing is decided yet.
Title: Re: 2015 sea ice area and extent data
Post by: Neven on June 23, 2015, 06:52:21 PM
From today's NSIDC sea ice concentration update I calculate the following future CT-area updates:

Fri       8.520306
Sat -35.0  8.485257
Sun -147.3  8.337926
Mon -169.4  8.168544
Tue -48.9  8.119646
Wed +0.3  8.119965


Wipneus, did you perhaps count a day double (maybe the one that has +0.3)? CT SIA is now one day ahead of IJIS SIE in my CAPIE spreadsheet (it used to be one day behind, with your calculations everything was going synchronously).  But maybe/probably I'm doing something wrong.
Title: Re: 2015 sea ice area and extent data
Post by: ChrisReynolds on June 23, 2015, 07:48:29 PM
No losses on Wednesday, expected CT-area updates from today's update of NSIDC sea ice concentration data:

Fri       8.520306
Sat -35.0  8.485257
Sun -147.3  8.337926
Mon -169.4  8.168544
Tue -48.9  8.119646
Wed +0.3  8.119995

Area in ESS and CAA went up (+22k5 and 13k7), Hudson and Baffin down (-18k and -16k4).

That takes me up to 23 June with CT Area data, albeit 'provisional'.

So my CT Area prediction for 2015 September minimum (daily value) is:

3.0 to 3.8M km^2, central value 3.4M km^2

The hindcasts for the model are 80% successful. In the post 2007 period there were two failures, 2009 and 2012 (0.18 and 0.17 respectively below the lower bound).

This prediction encompasses 2009, 2010, 2013 and 2014. This suggests a relatively normal post 2015 minimum.

Method described here:
http://dosbat.blogspot.co.uk/2015/05/predicting-ct-area-minimum.html (http://dosbat.blogspot.co.uk/2015/05/predicting-ct-area-minimum.html)

You recently wrote in your blog (post about possible crash this year) about the possibility of area going down in June (unremarkably) while June extent stalling. Compaction dropping, but still not meaning much in either direction.

So your method is purely quantitative, but still, don't you think your result has much to do with recent weather (and by recent I mean past 7 days).

A sensitivity test would consist on doing same math analysis for 15 June, or for July 1st when it comes. Just to see how your semi-statistical method converges...

Just a thought.

It was pointed out back in 2013 that this method is going to be overly sensitive to short term weather. Yes I could adapt it by filtering or averaging data around a date. Maybe that would decrease the sigma, and narrow the range?

Likewise the sensitivity test. You can see the tests I have done to select the date in the graph on my blog post. But running multiple predictions from multiple dates with multiple constants for the standard deviation of error, not to mention running hindcasts/forecasts for different past periods of data... It all sounds like a lot of programming (too complex for a speadsheet) and I hate programming.

In the end, CT Area isn't a dataset I use anymore since Wipneus figured out how they calculate it (and I wasn't impressed). So I can't be bothered. The method stands as it is, late summer losses in CT Area show virtually no trend which is a useful feature. As for trying to improve it, I can't be bothered.  :P  Sorry.

My main method remains April volume and NSIDC extent, that's simple too.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on June 24, 2015, 08:21:47 AM
From today's NSIDC sea ice concentration update I calculate the following future CT-area updates:

Fri       8.520306
Sat -35.0  8.485257
Sun -147.3  8.337926
Mon -169.4  8.168544
Tue -48.9  8.119646
Wed +0.3  8.119965


Wipneus, did you perhaps count a day double (maybe the one that has +0.3)? CT SIA is now one day ahead of IJIS SIE in my CAPIE spreadsheet (it used to be one day behind, with your calculations everything was going synchronously).  But maybe/probably I'm doing something wrong.

Neven,

I have not changed anything to the script that produces this list, nor do I see anything strange about the sequence.
It may mean nothing but you did not include the last line in your quote:
Quote
Thu -92.9  8.027085

Also note that the days in the list are the dates of the expected CT update, and starts with the last day that CT updated (last Friday at this moment).


Title: Re: 2015 sea ice area and extent data
Post by: Neven on June 24, 2015, 10:14:27 AM
From today's NSIDC sea ice concentration update I calculate the following future CT-area updates:

Fri       8.520306
Sat -35.0  8.485257
Sun -147.3  8.337926
Mon -169.4  8.168544
Tue -48.9  8.119646
Wed +0.3  8.119965


Wipneus, did you perhaps count a day double (maybe the one that has +0.3)? CT SIA is now one day ahead of IJIS SIE in my CAPIE spreadsheet (it used to be one day behind, with your calculations everything was going synchronously).  But maybe/probably I'm doing something wrong.

Neven,

I have not changed anything to the script that produces this list, nor do I see anything strange about the sequence.
It may mean nothing but you did not include the last line in your quote:
Quote
Thu -92.9  8.027085

Also note that the days in the list are the dates of the expected CT update, and starts with the last day that CT updated (last Friday at this moment).

Okay. I just fill in your calculated data in as preliminary data, in my CT spreadsheet and in my CAPIE spreadsheet. In the latter I noticed that CT SIA data was now 1 day ahead of IJIS SIE data. For instance, when IJIS SIE data was reported yesterday June the 23rd, the data was running up to June 22nd. But your preliminary CT SIA data was running up to June 23rd, on June 23rd. That's a combination of ultra-fast and a time zone difference thing.

But I've probably made a mistake somewhere. Thanks for checking.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on June 24, 2015, 11:09:58 AM
Let us have a look where we (dis)agree.

The last line in CT's data file is:

Quote
2015.4603  -1.2570381   8.5203056   9.7773438

The file date shows that the update was on:

Quote
Last-Modified: Fri, 19 Jun 2015 10:13:15 GMT

What date is meant by 2015.4603, and what date is it actually from?

And of course how was it entered in your spread sheet?

Here is my interpretation:

2015.4603 is 0.4603 years into 2015. That is 0.4603*365=168 days. Day 168 is the 17th of June.
(I base myself on something Dr. Chapman said a long time ago on ASIB, implying 2015.0000 in the file was actually 2014-12-31).

So CT says it reports data from the 17th in their update on the 19th.

My research has shown that this update is actually calculated from NSIDC sea ice concentration data that was published on the 17th of June and labeled as the 16th of June.

If you are still with me, this means there is actually a two day gap in NSIDC's data and CT-area data if you compare their day-to-day updates.

The data previously known as IJIS, is probably more like that from NSIDC. There should theoretically be a delay of 0.5 day due to the two day filtering but it is not obvious from their data (correlation).
Title: Re: 2015 sea ice area and extent data
Post by: Neven on June 24, 2015, 12:02:44 PM
Aha, so what CT reports as data for June 17th (like I have it in my spreadsheet, ie 8.5203056 for June 17th ), NSIDC reports as data for June 16th? That explains it then.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on June 24, 2015, 12:06:21 PM
Aha, so what CT reports as data for June 17th (like I have it in my spreadsheet, ie 8.5203056 for June 17th ), NSIDC reports as data for June 16th? That explains it then.

That is correct.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on June 24, 2015, 06:02:20 PM

From today's NSIDC sea ice concentration update I calculate the following future CT-area updates:
(starts with the last actual CT update on Friday, 19 June 2015)

Fri       8.520306
Sat -35.0  8.485257
Sun -147.3  8.337926
Mon -169.4  8.168544
Tue -48.9  8.119646
Wed +0.3  8.119965
Thu -92.5  8.027503
Fri -70.6  7.956866


Regions where area declined: CAB (-65k5), Baffin (-25k7), Hudson (-16k2) and Laptev (-12k2). Area increased in the Beaufort (+31k4) and "lakes" (+13k9).
In the attached delta map, pixels with larger concentration changes than 7% or colored pinkish (down) or light blue (up)

Title: Re: 2015 sea ice area and extent data
Post by: jdallen on June 24, 2015, 06:58:54 PM
The Wed. Number (0.3) still looks like a glitch.  Given the current heat exchange, at the peak of insolation, I'm hard pressed to come up with an explanation for it.
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on June 24, 2015, 08:58:51 PM
Cryosphere Today has finally updated its numbers through Day 0.4740. As follows:

2015.4630  -1.2066629   8.4857779   9.6924410
2015.4657  -1.2671592   8.3374977   9.6046572
2015.4685  -1.3478416   8.1689644   9.5168057
2015.4712  -1.3161162   8.1196880   9.4358044
2015.4740  -1.2032638   8.1203060   9.3235693

Anti-climactic, of course, since Wipneus already gave us the numbers...
Title: Re: 2015 sea ice area and extent data
Post by: jdallen on June 24, 2015, 10:24:15 PM
Cryosphere Today has finally updated its numbers through Day 0.4740. As follows:

2015.4630  -1.2066629   8.4857779   9.6924410
2015.4657  -1.2671592   8.3374977   9.6046572
2015.4685  -1.3478416   8.1689644   9.5168057
2015.4712  -1.3161162   8.1196880   9.4358044
2015.4740  -1.2032638   8.1203060   9.3235693

Anti-climactic, of course, since Wipneus already gave us the numbers...
2015.4740 still looks like a glitch.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on June 25, 2015, 04:11:44 PM
From today's NSIDC data update I calculate the following CT updates (by day that CT "normally" reports):

Wed       8.120306
Thu -92.5  8.027844
Fri -70.6  7.957204
Sat -123.8  7.833411

Biggest declines in Hudson (-37k), Baffin (-23k), Chukchi (-18k) and Greenland Sea (-13k).
In the attached delta map, pixels with larger concentration changes than 7% or colored pinkish (down) or light blue (up)
Title: Re: 2015 sea ice area and extent data
Post by: Neven on June 25, 2015, 04:53:55 PM
The Wed. Number (0.3) still looks like a glitch.  Given the current heat exchange, at the peak of insolation, I'm hard pressed to come up with an explanation for it.

CT itself has reported it too, but it's not unprecedented or anything. 2007 saw increases of 1999 km2 (June 23rd) and 15,672 km2 (June 27th), for instance.
Title: Re: 2015 sea ice area and extent data
Post by: ghoti on June 25, 2015, 05:10:45 PM
The delta map shows all of Lake Erie and Lake Ontario suddenly being completely ice covered. Seriously? They really have to fix that.
Title: Re: 2015 sea ice area and extent data
Post by: Nightvid Cole on June 25, 2015, 05:57:23 PM
OSISAF/MyOcean shows heavily reduced concentration now covering ~50% of the Arctic Ocean. How can CT not continue going further off the June cliff?



Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on June 25, 2015, 06:57:18 PM
The Wed. Number (0.3) still looks like a glitch.  Given the current heat exchange, at the peak of insolation, I'm hard pressed to come up with an explanation for it.

CT itself has reported it too, but it's not unprecedented or anything. 2007 saw increases of 1999 km2 (June 23rd) and 15,672 km2 (June 27th), for instance.
Indeed. 2012 itself saw a drop of 56,420 (0.4630). It happens...
Title: Re: 2015 sea ice area and extent data
Post by: jdallen on June 25, 2015, 07:02:14 PM
The Wed. Number (0.3) still looks like a glitch.  Given the current heat exchange, at the peak of insolation, I'm hard pressed to come up with an explanation for it.

CT itself has reported it too, but it's not unprecedented or anything. 2007 saw increases of 1999 km2 (June 23rd) and 15,672 km2 (June 27th), for instance.
Indeed. 2012 itself saw a drop of 56,420 (0.4630). It happens...
Precidented or not, it's counter to the heat flow in a major way, and begs an explanation.
Title: Re: 2015 sea ice area and extent data
Post by: sedziobs on June 25, 2015, 07:10:38 PM
Precidented or not, it's counter to the heat flow in a major way, and begs an explanation.

I see no reason to believe it's anything other than noise associated with remote sensing - the same reason why 5 day means are often used. 
Title: Re: 2015 sea ice area and extent data
Post by: Siffy on June 25, 2015, 07:59:01 PM
My thoughts are it's combination of many factors a few of which are melt ponds draining through cracks and movement of ice between scanning borders which allows for ice to be potentially counted twice and cloud cover.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on June 26, 2015, 08:21:03 AM
Looking at the day-to-day changes for the last three weeks, shows that the +0.3 glitch pales in comparison with the mega -340k "glitch" a week before. Explain that one before bothering with a point just a few k above several others that looks very much as the noise in the graph.

I would call neither a glitch, if it was so then a negative glitch would be followed by a return to normal: a positive spike. Likewise for a positive "glitch".

Title: Re: 2015 sea ice area and extent data
Post by: Lord M Vader on June 26, 2015, 08:55:04 AM
Morning guys!

I just found this interesting product with perhaps a daily calculation of the volume in the Arctic basin in combination with a estimated ice thickness. Have you seen it before? What kind of value does it have?

http://ocean.dmi.dk/arctic/icethickness/thk.uk.php (http://ocean.dmi.dk/arctic/icethickness/thk.uk.php)

http://ocean.dmi.dk/arctic/icethickness/images/FullSize_CICE_combine_thick_SM_EN_20150625.png (http://ocean.dmi.dk/arctic/icethickness/images/FullSize_CICE_combine_thick_SM_EN_20150625.png)

This is another map of the modelled ice thickness including a forecast for the next 5 days. Of interest is only the Arctic Sea and to some degree Greenland. Unfortunely, the five last parameters don't work for the Arctic Sea.

http://ocean.dmi.dk/anim/index.uk.php (http://ocean.dmi.dk/anim/index.uk.php)

Most interesting is the forecast of the sea ice thickness around the North Pole which is foreseen to be less than 1,5 m by June 30....

Oh, finally a link to satellite images around Greenland including Nares Strait :)
http://ocean.dmi.dk/arctic/morrisjessup.uk.php (http://ocean.dmi.dk/arctic/morrisjessup.uk.php)

and a link to Greenland ice charts. http://ocean.dmi.dk/arctic/icecharts_gl_1.uk.php (http://ocean.dmi.dk/arctic/icecharts_gl_1.uk.php)

Sincerely, LMV
Title: Re: 2015 sea ice area and extent data
Post by: wanderer on June 26, 2015, 09:01:55 AM
Day 173: CT area

2015: 8.12031 million sq. km
2012: 7.72807 million sq. km

Difference just about 400k

2015 is 200k behind in Baffin, 100k in Kara, these regions will melt out anyway and won't trigger or delay other melting, so actually we are (100k) close to 2012

Nevertheless, 2012-arcticseaice still looks weeker to me here:
http://igloo.atmos.uiuc.edu/cgi-bin/test/print.sh?fm=06&fd=23&fy=2012&sm=06&sd=23&sy=2015 (http://igloo.atmos.uiuc.edu/cgi-bin/test/print.sh?fm=06&fd=23&fy=2012&sm=06&sd=23&sy=2015)

Here, 2015-arcticseaice seems to be (much!) weeker:
http://www7320.nrlssc.navy.mil/hycomARC/navo/arcticict/nowcast/ict2015062418_2015062500_040_arcticict.001.gif (http://www7320.nrlssc.navy.mil/hycomARC/navo/arcticict/nowcast/ict2015062418_2015062500_040_arcticict.001.gif)
http://www7320.nrlssc.navy.mil/hycomARC/navo/arcticict/nowcast/ict2012062418_2012062500_035_arcticict.001.gif (http://www7320.nrlssc.navy.mil/hycomARC/navo/arcticict/nowcast/ict2012062418_2012062500_035_arcticict.001.gif)
(But i think ice thickness was underestimated in 2013 and 2014 as well...)
Title: Re: 2015 sea ice area and extent data
Post by: jdallen on June 26, 2015, 09:23:17 AM
Looking at the day-to-day changes for the last three weeks, shows that the +0.3 glitch pales in comparison with the mega -340k "glitch" a week before. Explain that one before bothering with a point just a few k above several others that looks very much as the noise in the graph.

I would call neither a glitch, if it was so then a negative glitch would be followed by a return to normal: a positive spike. Likewise for a positive "glitch".
Can't argue with your logic; -340 is definitely glitchy as hell.

Can't say it necessarily makes 0.3 less or more glitchy, so I'll disagree with the notion I need to solve the -340 problem before the 0.3 problem.

It does point towards problems with the day-over-day sampling of extent and area.
Title: Re: 2015 sea ice area and extent data
Post by: slow wing on June 26, 2015, 09:34:04 AM
Morning guys!

I just found this interesting product with perhaps a daily calculation of the volume in the Arctic basin in combination with a estimated ice thickness. Have you seen it before? What kind of value does it have?

http://ocean.dmi.dk/arctic/icethickness/thk.uk.php (http://ocean.dmi.dk/arctic/icethickness/thk.uk.php)

http://ocean.dmi.dk/arctic/icethickness/images/FullSize_CICE_combine_thick_SM_EN_20150625.png (http://ocean.dmi.dk/arctic/icethickness/images/FullSize_CICE_combine_thick_SM_EN_20150625.png)

This is another map of the modelled ice thickness including a forecast for the next 5 days. Of interest is only the Arctic Sea and to some degree Greenland. Unfortunely, the five last parameters don't work for the Arctic Sea.

http://ocean.dmi.dk/anim/index.uk.php (http://ocean.dmi.dk/anim/index.uk.php)

Most interesting is the forecast of the sea ice thickness around the North Pole which is foreseen to be less than 1,5 m by June 30....

Oh, finally a link to satellite images around Greenland including Nares Strait :)
http://ocean.dmi.dk/arctic/morrisjessup.uk.php (http://ocean.dmi.dk/arctic/morrisjessup.uk.php)

and a link to Greenland ice charts. http://ocean.dmi.dk/arctic/icecharts_gl_1.uk.php (http://ocean.dmi.dk/arctic/icecharts_gl_1.uk.php)

Sincerely, LMV
Nice find!
Maybe others are already familiar with it, but a daily updated ice thickness map is very interesting!

PS it says it uses the DMI HYCOM-CICE model. How is this related to the CICE model that is linked to Neven's graphs page & appears here:
http://www7320.nrlssc.navy.mil/hycomARC/arctic.html (http://www7320.nrlssc.navy.mil/hycomARC/arctic.html)
?
Title: Re: 2015 sea ice area and extent data
Post by: Jim Hunt on June 26, 2015, 12:07:05 PM
I just found this interesting product with perhaps a daily calculation of the volume in the Arctic basin in combination with a estimated ice thickness. Have you seen it before? What kind of value does it have?

The individual maps/graphs are available in larger format via the Polar Portal. See e.g.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fpolarportal.dk%2Ffileadmin%2Fpolarportal%2Fsea%2FCICE_map_thick_LA_EN_20150625.png&hash=b9f158de5e064de3df46e5247f8864cb)

This is probably not the sort of value you had in mind, but I used one of them to pull "Steve Goddard's" chain the other day:

Does a Lie Told Often Enough Become the Truth? (http://GreatWhiteCon.info/2015/06/does-a-lie-told-often-enough-become-the-truth/#DMI-Volume)

Regarding real value, then I suppose ongoing comparisons with ACNFS/PIOMAS are in order?
Title: Re: 2015 sea ice area and extent data
Post by: slow wing on June 26, 2015, 12:49:22 PM
Someone's plonked down a giant spade next to Greenland and scraped a furrow in the ice all the way to Siberia!
Title: Re: 2015 sea ice area and extent data
Post by: Jim Hunt on June 26, 2015, 12:57:49 PM
it says it uses the DMI HYCOM-CICE model. How is this related to the CICE model that is linked to Neven's graphs page?

DMI aren't very specific, but it sounds like much the same model with ECMWF instead of NAVGEM forcing. The CICE version number isn't mentioned either. Version 5 is now out there, but ACNFS/GOFS still use version 4 as far as I am aware.
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on June 26, 2015, 01:21:11 PM
ADS-NIPR Extent:
9,883,311 km2 (25 June)
Down 4,058,749 km2 (29.11%) from 2015 maximum of 13,942,060 km2 on 15 February.
6,705,856 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Down 33,495 km2 from previous day.
Down 227,522 km2 over past seven days (daily average: -32,503 km2).
Down 995,260 km2 for the month of June (daily average: -39,810 km2).
392,371 km2 below 2000s average for this date.
197,606 km2 above 2010s average for this date.
191,982 km2 above 2014 value for this date.
389,614 km2 above 2012 value for this date.
3rd lowest June to-date average.
6th lowest value for the date.
64 days this year (36.36% year-to-date) have recorded the lowest daily extent.
32 days (18.18%) have recorded the second lowest.
32 days (18.18%) have recorded the third lowest.
128 days (72.73%) in total have been among the three lowest on record.

Falling further and further behind:
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2F6uBC6W6.png&hash=3d00ceb315d2e053affbfccb55ae2d6a)


CT Area:
NOTE: due to the absence of official CT sea ice area data, I've instead used Wipneus' calculated area numbers for Days 0.4767 - 0.4795. The official numbers will be inserted if/when available. In the meantime, thanks, Wipneus!
7,957,204 km2 (25 June [Day 0.4795])
Down 5,317,351 km2 (40.06%) from 2015 maximum of 13,274,555 km2 on 17 February [Day 0.1288].
5,723,195 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Down 70,640 km2 from previous day.
Down 563,102 km2 over past seven days (daily average: -80,443 km2).
Down 2,179,377 km2 for the month of June (daily average: -87,175 km2).
433,249 km2 below 2000s average for this date.
159,374 km2 above 2010s average for this date.
60,690 km2 below 2014 value for this date.
585,975 km2 above 2012 value for this date.
7th lowest June to-date average.
6th lowest value for the date.
7 days this year (3.98% year-to-date) have recorded the lowest daily area.
19 days (10.8%) have recorded the second lowest.
29 days (16.48%) have recorded the third lowest.
55 days in total (31.25%) have been among the lowest three on record.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on June 26, 2015, 04:29:36 PM
From today's NSIDC data update I calculate the following CT updates (by day that CT "normally" reports, starting with the day of the last day that CT updated its data):

Wed       8.120306
Thu -92.5  8.027844
Fri -70.6  7.957204
Sat -123.7  7.833457
Sun -45.5  7.787915

That is with help from the "lake ice" dropping -10k. Other regions that declined are CAB (-22k3), Beaufort (-15k5), Greenland Sea (-13k5)  and Hudson (-13k1). Area increases in Laptev (+25k5) and CAA (+12k2).
In the attached delta map, pixels with larger concentration changes than 7% or colored pinkish (down) or light blue (up)
Title: Re: 2015 sea ice area and extent data
Post by: Tor Bejnar on June 26, 2015, 05:22:33 PM
I really appreciate your adding the pinks and light blues, Wipneus.  It gives a sense of 'trending'.  Thanks!
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on June 27, 2015, 04:25:54 PM
From today's NSIDC data update I calculate the following CT updates (by day that CT "normally" reports, starting with the day of the last day that CT updated its data):

Wed       8.120306
Thu -92.5  8.027844
Fri -70.6  7.957204
Sat -123.7  7.833457
Sun -45.5  7.787983
Mon -79.3  7.708670

Declines in the CAB (-56k), Hudson (-27k) and Kara (-15k2). Area increases inCAA (+13k3) and ESS (+12k2).

In the attached NSIDC delta map, pixels with larger concentration changes than 7% or colored pinkish (down) or light blue (up). Solid red and blue are where the pixel concentration crosses the 15% limit (for extent).
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on June 28, 2015, 03:12:57 PM
ADS-NIPR Extent:
9,731,983 km2 (27 June)
Down 4,210,077 km2 (30.2%) from 2015 maximum of 13,942,060 km2 on 15 February.
6,554,528 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Down 85,736 km2 from previous day.
Down 354,982 km2 over past seven days (daily average: -50,712 km2).
Down 1,146,588 km2 for the month of June (daily average: -42,466 km2).
409,126 km2 below 2000s average for this date.
237,313 km2 above 2010s average for this date.
224,853 km2 above 2014 value for this date.
395,909 km2 above 2012 value for this date.
3rd lowest June to-date average.
6th lowest value for the date.
64 days this year (35.96% year-to-date) have recorded the lowest daily extent.
32 days (17.98%) have recorded the second lowest.
32 days (17.98%) have recorded the third lowest.
128 days (71.91%) in total have been among the three lowest on record.


CT Area:
7,787,654 km2 (27 June [Day 0.485])
Down 5,486,901 km2 (41.33%) from 2015 maximum of 13,274,555 km2 on 17 February [Day 0.1288].
5,553,645 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Down 45,791 km2 from previous day.
Down 549,843 km2 over past seven days (daily average: -78,549 km2).
Down 2,348,926 km2 for the month of June (daily average: -86,997 km2).
375,231 km2 below 2000s average for this date.
236,417 km2 above 2010s average for this date.
64,977 km2 below 2014 value for this date.
675,500 km2 above 2012 value for this date.
6th lowest June to-date average.
7th lowest value for the date.
7 days this year (3.93% year-to-date) have recorded the lowest daily area.
19 days (10.67%) have recorded the second lowest.
29 days (16.29%) have recorded the third lowest.
55 days in total (30.9%) have been among the lowest three on record.



Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on June 28, 2015, 05:00:39 PM
From today's NSIDC data update I calculate the following CT updates (by day that CT "normally" reports, starting with the day of the last day that CT updated its data):

Sun       7.787654
Mon -79.8  7.707865
Tue -144.1  7.563812

Perhaps we are in for a late June cliff. Biggest decline is the CAB (-70k5) but I think the most impressive is Laptev at -67k7. With Beaufort (-18k6) , the Basin is in solid decline.

In the attached NSIDC delta map, pixels with larger concentration changes than 7% or colored pinkish (down) or light blue (up). Solid red and blue are where the pixel concentration crosses the 15% limit (for extent).
Title: Re: 2015 sea ice area and extent data
Post by: BornFromTheVoid on June 28, 2015, 07:17:33 PM
Update for the week to June 28th

The current 5 day mean is on 10,413,200km2 while the 1 day extent is at 10,280,000km2.
The daily anomaly (compared to 81-10) is at -831,290km2, a decrease from -887,150km2 last week. The anomaly compared to the 07, 11 and 12 average is at +299,000km2, an increase from +98,467km2 last week. We're currently 7th lowest on record, down from 4th last week.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FcWuZWyX.png&hash=8b9c563db6f249f3a78d15ebf59a628b)

The average daily change over the last 7 days was -52.5k/day, compared to the long term average of -60.5k/day, and the 07, 11 and 12 average of -81.1k/day.
The average long term change over the next week is -85.2k/day, with the 07, 11, and 12 average being -124.6k/day.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2F8DEgHLZ.png&hash=2de13751813f14031633a164008ed506)

The loss so far this June is the 18th largest on record. To achieve the largest monthly drop, a daily loss of at least 503.9k/day is required, while the smallest drop requires an increase of at least than 105.6k/day and an average drop requires a loss of 95.5k/day.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FilrlXwh.png&hash=00f17c27b864440ca83b7e2147057729)
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on June 29, 2015, 04:31:09 PM
From today's NSIDC data update I calculate the following CT updates (by day that CT "normally" reports, starting with the day of the last day that CT updated its data):

Mon       7.707334
Tue -143.9  7.563430
Wed -108.4  7.455033

Wednesday would not be a century without the help of "lake ice" (-16k). Biggest declines were Hudson (-44k5), CAB (-29k2), Baffin (-20k6) and Kara (-18k1). Ice are grew in Beaufort (+21k) and Laptev (+19k1).

In the attached NSIDC delta map, pixels with larger concentration changes than 7% or colored pinkish (down) or light blue (up). Solid red and blue are where the pixel concentration crosses the 15% limit (for extent).
Title: Re: 2015 sea ice area and extent data
Post by: jdallen on June 29, 2015, 05:34:46 PM
Let see if I've got this right. By wipneus' numbers, June 25 through 30 inclusive, the ice has/will decline 540k KM2, or an average of about 90K per day.

Wednesday starts July off with a century break, after which it looks like the weather gets worse.

So, what does the ice outlook appear to be if we lose 3 million KM2 in July? How probable would that be?
Title: Re: 2015 sea ice area and extent data
Post by: oren on June 29, 2015, 05:36:33 PM
It seems Hudson is finally giving way. It held up remarkably well until now.
Title: Re: 2015 sea ice area and extent data
Post by: Tor Bejnar on June 29, 2015, 06:03:29 PM
jdallen,
When you write "it looks like the weather gets worse", it not obvious whether you mean 'worse for ice' or 'worse for beast'.  One may mean sunny skies; the other (traditionally), snow and cold wind ["It ain't a fit night out for man or beast." (https://www.youtube.com/watch?v=VcGfuEZ9dSo)].  (In the long run, or course, melted ice is not good for the current assemblage of mammals that wander in the Arctic.)

From context, I think you mean 'worse for ice'.

This imprecision is a recurring problem in this forum; I'm sure I do it too.
Title: Re: 2015 sea ice area and extent data
Post by: Buddy on June 29, 2015, 06:28:26 PM
Quote
This imprecision is a recurring problem in this forum

It is also, unfortunately, a problem with the English language.....AND.....a problem with humans in general (we ALWAYS know what WE mean.....and don't understand why other people don't understand US:)

That is one of the reasons the US has SOOOOO many lawyers (imprecise English language, and imprecise humans that don't communicate CLEARLY).  We ALL do it.....unfortunately.

Title: Re: 2015 sea ice area and extent data
Post by: Tensor on June 29, 2015, 10:46:47 PM
We ALL do it.....unfortunately.

Not true. Obviously, the last few post talk about how the clear humans wandering the arctic are made of ice from beasts.   
Title: Re: 2015 sea ice area and extent data
Post by: DavidR on June 29, 2015, 11:15:33 PM
Let see if I've got this right. By wipneus' numbers, June 25 through 30 inclusive, the ice has/will decline 540k KM2, or an average of about 90K per day.

Wednesday starts July off with a century break, after which it looks like the weather gets worse.

So, what does the ice outlook appear to be if we lose 3 million KM2 in July? How probable would that be?
jda,
you  are forgetting thay Wipneus' figures are 'day released', not 'day measured'  Wed in this case means measured on Sunday (28th).
Title: Re: 2015 sea ice area and extent data
Post by: jdallen on June 30, 2015, 04:45:26 AM

From context, I think you mean 'worse for ice'.

This imprecision is a recurring problem in this forum; I'm sure I do it too.
Sorry - it is something I've also noticed and normally attempt to stay ahead of, at the risk of being pedantic.

Thank you for the criticism.
Title: Re: 2015 sea ice area and extent data
Post by: jdallen on June 30, 2015, 04:50:33 AM
Let see if I've got this right. By wipneus' numbers, June 25 through 30 inclusive, the ice has/will decline 540k KM2, or an average of about 90K per day.

Wednesday starts July off with a century break, after which it looks like the weather gets worse.

So, what does the ice outlook appear to be if we lose 3 million KM2 in July? How probable would that be?
jda,
you  are forgetting thay Wipneus' figures are 'day released', not 'day measured'  Wed in this case means measured on Sunday (28th).

Hmmm.  Suggests the cascade off of the cliff is even steeper, which in context of the weather, makes sense.

My over all point is, in spite of perceptions that somehow, 2015 wasn't keeping up with the lowest three years, weather *is* pushing melt hard, even if has not followed arbitrary human perceptions of timing.
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on June 30, 2015, 12:49:22 PM
Let see if I've got this right. By wipneus' numbers, June 25 through 30 inclusive, the ice has/will decline 540k KM2, or an average of about 90K per day.

Wednesday starts July off with a century break, after which it looks like the weather gets worse.

So, what does the ice outlook appear to be if we lose 3 million KM2 in July? How probable would that be?

Losing 3 million km2 of area in July isn't unprecedented; it happened in both 2007 and 2009 (and 2013 came close with a decrease of 2.89 million). But losing 3 million this year would give SIA a month-ending value of 4.5 million km2, which would still leave 2015 in 5th place behind 2012, 2011, 2007, and 2010. (To begin August in the top three, July would have to see more than 3.2 million km2 of area disappear, and that's never happened.)

In short: time is running out for the 2015 SIA minimum to even crack the top three years on record. That's not to say it can't or won't happen; July and August weather can cause wild swings either way. We could see a GAC event like in 2012 that eats ice by the gigaton. Or we could see a ten-day period at the end of July like we did in 2013 where area actually grew by 20k km2.

Ah, the fun of watching the ice... :)
Title: Re: 2015 sea ice area and extent data
Post by: Jim Hunt on June 30, 2015, 03:09:40 PM
DMI aren't very specific, but it sounds like much the same model with ECMWF instead of NAVGEM forcing

I've now received some additional information from DMI:

Quote
Our operational model system consists of the HYCOM version 2.2.55 and CICE version 4.0 models, coupled using the ESMF coupler. The model resolution is about 10 km, and the domain covers the Arctic Ocean and the Atlantic Ocean to approximately 20°S. We currently use ECMWF operational atmospheric forcing, and the model assimilates OSISAF reanalysed sea ice concentration and GHRSST Level 4 DMI_OI sea surface temperatures.

There's a publicly available description of the operational model setup here: http://ocean.dmi.dk/models/hycom.uk.php (http://ocean.dmi.dk/models/hycom.uk.php)

We can be contacted through this page: http://www.dmi.dk/en/about/dmi-online/contact-dmi/ (http://www.dmi.dk/en/about/dmi-online/contact-dmi/)
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on June 30, 2015, 05:10:16 PM
From today's NSIDC data update I calculate the following CT updates (the days in this list are the days of data released, three days behind ice dates):

Mon       7.707334
Tue -143.9  7.563430
Wed -108.8  7.454602
Thu -34.0  7.420578

That would have been only -26k without the "lake ice". There were declines in Barents (-14k) and Baffin (-12k). Area increased in the CAB (+23k1) and Kara (+12k8).

In the attached NSIDC delta map, pixels with larger concentration changes than 7% or colored pinkish (down) or light blue (up). Solid red and blue are where the pixel concentration crosses the 15% limit (for extent).
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on June 30, 2015, 07:04:40 PM
From today's NSIDC data update I calculate the following CT updates (the days in this list are the days of data released, three days behind ice dates):

Mon       7.707334
Tue -143.9  7.563430
Wed -108.8  7.454602
Thu -34.0  7.420578


And the painfully slow melt continues. These numbers will drop 2015 back to 8th place, behind 2012, 2010, 2011, 2007, 2013, 2014, and 2008. In fact, the difference between 2012 and this year will be over 800,000 km2, the widest gap so far this year. 2015 has struggled to put together any extended strings of consecutive century breaks, and failed.
Title: Re: 2015 sea ice area and extent data
Post by: sedziobs on June 30, 2015, 07:13:58 PM
It should be noted from the Regional Graphs page that area is comparatively low in the CAB and Chukchi; high in Hudson, Baffin and Barents; and mixed in the other seas.  In the areas where melt is lagging, we would still expect a complete melt in the next month.
Title: Re: 2015 sea ice area and extent data
Post by: jdallen on June 30, 2015, 10:13:25 PM
From today's NSIDC data update I calculate the following CT updates (the days in this list are the days of data released, three days behind ice dates):

Mon       7.707334
Tue -143.9  7.563430
Wed -108.8  7.454602
Thu -34.0  7.420578


And the painfully slow melt continues. These numbers will drop 2015 back to 8th place, behind 2012, 2010, 2011, 2007, 2013, 2014, and 2008. In fact, the difference between 2012 and this year will be over 800,000 km2, the widest gap so far this year. 2015 has struggled to put together any extended strings of consecutive century breaks, and failed.

The numbers are what you say, but they make utterly no sense.  Weather *absolutely* is better for melt than 2013 and 2014.  More heat is entering the arctic, yet here we are.
Title: Re: 2015 sea ice area and extent data
Post by: epiphyte on July 01, 2015, 06:25:04 AM
From today's NSIDC data update I calculate the following CT updates (the days in this list are the days of data released, three days behind ice dates):

Mon       7.707334
Tue -143.9  7.563430
Wed -108.8  7.454602
Thu -34.0  7.420578


And the painfully slow melt continues. These numbers will drop 2015 back to 8th place, behind 2012, 2010, 2011, 2007, 2013, 2014, and 2008. In fact, the difference between 2012 and this year will be over 800,000 km2, the widest gap so far this year. 2015 has struggled to put together any extended strings of consecutive century breaks, and failed.

Melt is not, not, not, the same thing as decrease in extent.
Melt is not, not, not the same thing as decrease in area.

Does anyone seriously dispute that?


Title: Re: 2015 sea ice area and extent data
Post by: LRC1962 on July 01, 2015, 07:01:28 AM

Melt is not, not, not, the same thing as decrease in extent.
Melt is not, not, not the same thing as decrease in area.

Does anyone seriously dispute that?
Technically correct. But from my observation in this forum it is a shortcut to describing decreases. That would include, melting, exporting, compaction and any other reason for that decrease. From there we then go and sometimes discuss Why the decrease. True melt is always part of the equation, but almost always only a part. Example: decreases in September rarely have to do with melting, Sometimes export, more often compaction.
Where 'melt' also gets involved in is the thinning of the ice.
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on July 01, 2015, 01:50:14 PM
Melt is not, not, not, the same thing as decrease in extent.
Melt is not, not, not the same thing as decrease in area.

Does anyone seriously dispute that?

Of course not. But in the popular press, the term "melt" is used most often when talking about the Arctic sea ice disappearing, so I too--as a non-professional scientist--most often use the term "melt" as shorthand for all forms of ice decrease for the sake of brevity. Most laypeople read of the Arctic sea ice "melting"; they neither know nor care about compaction, or sublimation, or export. So when I write something here such as "the painfully slow melt continues", I'm trusting that everyone reading it is knowledgeable enough to understand that I'm referring to all manner of sea ice extent and area decrease.
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on July 01, 2015, 03:28:46 PM
ADS-NIPR Extent:
9,482,316 km2 (30 June)
Down 4,459,744 km2 (31.99%) from 2015 maximum of 13,942,060 km2 on 15 February.
6,304,861 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Down 59,822 km2 from previous day.
Down 482,568 km2 over past seven days (daily average: -68,938 km2).
Down 1,396,255 km2 for the month of June (daily average: -46,542 km2).
423,885 km2 below 2000s average for this date.
287,281 km2 above 2010s average for this date.
424,759 km2 above 2014 value for this date.
442,405 km2 above 2012 value for this date.
4th lowest June average.
7th lowest value for the date.
64 days this year (35.36% year-to-date) have recorded the lowest daily extent.
32 days (17.68%) have recorded the second lowest.
32 days (17.68%) have recorded the third lowest.
128 days (70.72%) in total have been among the three lowest on record.


CT Area:
7,454,821 km2 (30 June [Day 0.4932])
Down 5,819,735 km2 (43.84%) from 2015 maximum of 13,274,555 km2 on 17 February [Day 0.1288].
5,220,811 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Down 109,291 km2 from previous day.
Down 665,485 km2 over past seven days (daily average: -95,069 km2).
Down 2,681,760 km2 for the month of June (daily average: -89,392 km2).
453,410 km2 below 2000s average for this date.
237,587 km2 above 2010s average for this date.
84,658 km2 below 2014 value for this date.
725,730 km2 above 2012 value for this date.
7th lowest June average.
5th lowest value for the date.
7 days this year (3.87% year-to-date) have recorded the lowest daily area.
19 days (10.5%) have recorded the second lowest.
29 days (16.02%) have recorded the third lowest.
55 days in total (30.39%) have been among the lowest three on record.
Title: Re: 2015 sea ice area and extent data
Post by: epiphyte on July 01, 2015, 09:05:06 PM
Melt is not, not, not, the same thing as decrease in extent.
Melt is not, not, not the same thing as decrease in area.

Does anyone seriously dispute that?

Of course not. But in the popular press, the term "melt" is used most often when talking about the Arctic sea ice disappearing, so I too--as a non-professional scientist--most often use the term "melt" as shorthand for all forms of ice decrease for the sake of brevity. Most laypeople read of the Arctic sea ice "melting"; they neither know nor care about compaction, or sublimation, or export. So when I write something here such as "the painfully slow melt continues", I'm trusting that everyone reading it is knowledgeable enough to understand that I'm referring to all manner of sea ice extent and area decrease.

Understood - but if everyone uses the word "melt" as a proxy for decreases in area and/or extent, then it closes people's minds to the possibility that there can be aggressive melt (i.e. reduction in volume) occurring without changing the extent much at all.

Conversely, if the extent were to drop off a huge cliff sometime soon, which IMO is quite probable, it would not be because all the ice that was there in April melted at once.
Title: Re: 2015 sea ice area and extent data
Post by: ChrisReynolds on July 01, 2015, 10:48:05 PM
From today's NSIDC data update I calculate the following CT updates (the days in this list are the days of data released, three days behind ice dates):

Mon       7.707334
Tue -143.9  7.563430
Wed -108.8  7.454602
Thu -34.0  7.420578


And the painfully slow melt continues. These numbers will drop 2015 back to 8th place, behind 2012, 2010, 2011, 2007, 2013, 2014, and 2008. In fact, the difference between 2012 and this year will be over 800,000 km2, the widest gap so far this year. 2015 has struggled to put together any extended strings of consecutive century breaks, and failed.

The numbers are what you say, but they make utterly no sense.  Weather *absolutely* is better for melt than 2013 and 2014.  More heat is entering the arctic, yet here we are.

2007 to 2012 summers were dominated by a dipole, low over coastal Siberia, high over the Arctic ice pack and Greenland. The Greenland high increased export through Fram, the dipole between the Arctic Ocean and Siberia drew in warm Pacific air. This state has not developed so far this year, all we have had is fleeting occurences of daily patterns that could have developed into a 2007 to 2012 type dipole pattern but didn't. In the first half of June a strong dipole between a low centred on Barents and the Greenland high developed, it kept Greenland sea area up - a sign of strong export. Since about 14 June vector winds over the Fram Strait have been normal and Greenland sea export has faltered leading to a decrease in area similar to the climatological mean loss.

Yes, this year is warm, yes conditions for melt are better than 2013 /2014. But because of the large scale synoptic pattern and lack of the 2007 to 2012 dipole type pattern, prospects for a melt towards the lowest of the 2007 to 2012 years is poor. Something around the median of the range of 2007 to 2012 years is the most likely outcome for September.
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on July 01, 2015, 11:07:36 PM
Melt is not, not, not, the same thing as decrease in extent.
Melt is not, not, not the same thing as decrease in area.

Does anyone seriously dispute that?

Of course not. But in the popular press, the term "melt" is used most often when talking about the Arctic sea ice disappearing, so I too--as a non-professional scientist--most often use the term "melt" as shorthand for all forms of ice decrease for the sake of brevity. Most laypeople read of the Arctic sea ice "melting"; they neither know nor care about compaction, or sublimation, or export. So when I write something here such as "the painfully slow melt continues", I'm trusting that everyone reading it is knowledgeable enough to understand that I'm referring to all manner of sea ice extent and area decrease.

Understood - but if everyone uses the word "melt" as a proxy for decreases in area and/or extent, then it closes people's minds to the possibility that there can be aggressive melt (i.e. reduction in volume) occurring without changing the extent much at all.

Conversely, if the extent were to drop off a huge cliff sometime soon, which IMO is quite probable, it would not be because all the ice that was there in April melted at once.

Again: "[W]hen I write something here such as "the painfully slow melt continues", I'm trusting that everyone reading it is knowledgeable enough to understand that I'm referring to all manner of sea ice extent and area decrease." I seriously doubt that I'm closing anyone's mind to "...the possibility that there can be aggressive melt". I'm just just employing a well-understood, widely-used shorthand term for ice loss without actually repeating the terms "loss" or "decrease" a dozen times in each sentence.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on July 02, 2015, 08:21:58 AM
From yesterday's NSIDC data update I calculate the following CT updates (the days in this list are the days of data released, three days behind ice dates):
Wed       7.454821
Thu -34.3  7.420529
Fri -139.8  7.280707

Biggest declines outside the Basin in Baffin (-42k), Hudson (-25k5) and Kara (-14k1). Within the Basin ESS dropped -25k1.

In the attached NSIDC delta map, pixels with larger concentration changes than 7% or colored pinkish (down) or light blue (up). Solid red and blue are where the pixel concentration crosses the 15% limit (for extent).

Note: due to computer problems (the local heatwave seems to affect the aging silicon or something) this message came to you with a delay. This may last for some time until I have wired up another computer, affecting my other regular forum activities (PIOMAS and "Home Brew") as well. Cooler weather is expected this Sunday.
Title: Re: 2015 sea ice area and extent data
Post by: epiphyte on July 02, 2015, 09:06:04 AM
Melt is not, not, not, the same thing as decrease in extent.
Melt is not, not, not the same thing as decrease in area.

Does anyone seriously dispute that?

Of course not. But in the popular press, the term "melt" is used most often when talking about the Arctic sea ice disappearing, so I too--as a non-professional scientist--most often use the term "melt" as shorthand for all forms of ice decrease for the sake of brevity. Most laypeople read of the Arctic sea ice "melting"; they neither know nor care about compaction, or sublimation, or export. So when I write something here such as "the painfully slow melt continues", I'm trusting that everyone reading it is knowledgeable enough to understand that I'm referring to all manner of sea ice extent and area decrease.

Understood - but if everyone uses the word "melt" as a proxy for decreases in area and/or extent, then it closes people's minds to the possibility that there can be aggressive melt (i.e. reduction in volume) occurring without changing the extent much at all.

Conversely, if the extent were to drop off a huge cliff sometime soon, which IMO is quite probable, it would not be because all the ice that was there in April melted at once.

Again: "[W]hen I write something here such as "the painfully slow melt continues", I'm trusting that everyone reading it is knowledgeable enough to understand that [...]


Bad idea. If you say  "the painfully slow melt continues" [...]   ,under the assumption that others can be relied upon to translate what you say into what you mean,  the only thing you can be sure of is that someone else will pick up on what you said, attribute to you it's literal meaning, and then hang it around your neck.

...and again. "all manner of sea ice extent and area decrease"  is not synonymous with "melt". The two aren't totally independent, but they are far from in lockstep with each other.


 



Title: Re: 2015 sea ice area and extent data
Post by: Neven on July 02, 2015, 09:56:02 AM
Note: due to computer problems (the local heatwave seems to affect the aging silicon or something) this message came to you with a delay. This may last for some time until I have wired up another computer, affecting my other regular forum activities (PIOMAS and "Home Brew") as well. Cooler weather is expected this Sunday.

Hang in there, Wip! The 'ellende' has just started in Austria as well.

Quote
Bad idea. If you say  "the painfully slow melt continues" [...]   ,under the assumption that others can be relied upon to translate what you say into what you mean,  the only thing you can be sure of is that someone else will pick up on what you said, attribute to you it's literal meaning, and then hang it around your neck.

I don't agree. In that case we may all as well stop writing. Most people know what is meant with 'melt' in this context. If they don't, you explain. I get this all the time with the "good/bad weather stuff", and I'm glad it pops up, because it offers me the chance to espouse my views about good and bad wrt Arctic sea ice loss.
Title: Re: 2015 sea ice area and extent data
Post by: DavidR on July 02, 2015, 04:13:46 PM
Well the June figures for NSIDC extent are in, and at just 1.864 M km^2  its the smallest drop since 2004 which fell just over 1.2 M km^2.  At the time 2004 was the 9th lowest on record but by the end of the season it had dropped to 3rd lowest on record.

We didn't even get near the statistical 260 K anomalous drop that we normally see on July 1st.  The only  recent time we haven't seem this drop on July 1st it showed up on July 2nd so it will be interesting to see what  tomorrow brings.

All in all still an interesting season where anything can happen if the el Nino starts to  bite.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on July 02, 2015, 04:49:08 PM
From yesterday's NSIDC data update I calculate the following CT updates (the days in this list are the days of data released, three days behind ice dates):

Thu       7.419765
Fri -138.9  7.280890
Sat -177.8  7.103101


That is including the "first of the month" effect. This effect is much less than extent but still perhepa -40k. Even without that effect, there is still a big drop within the Basin. It was visible on ADS-NIPR Jaxa's thickness/melting map as well, so the phrase "melting" does not seem out of place.
Biggest declines within the basin: ESS (-44k 1), Laptev (-29k7), Beaufort (-21k4) Chukchi (-13k7). Outside the basin there is Baffin with -23k8, but this region will be affected by the 1st of the month effect.

In the attached NSIDC delta map, pixels with larger concentration changes than 7% or colored pinkish (down) or light blue (up). Solid red and blue are where the pixel concentration crosses the 15% limit (for extent).
Title: Re: 2015 sea ice area and extent data
Post by: Nightvid Cole on July 02, 2015, 04:53:01 PM
Well the June figures for NSIDC extent are in, and at just 1.864 M km^2  its the smallest drop since 2004 which fell just over 1.2 M km^2.  At the time 2004 was the 9th lowest on record but by the end of the season it had dropped to 3rd lowest on record.

We didn't even get near the statistical 260 K anomalous drop that we normally see on July 1st.  The only  recent time we haven't seem this drop on July 1st it showed up on July 2nd so it will be interesting to see what  tomorrow brings.

All in all still an interesting season where anything can happen if the el Nino starts to  bite.

El nino is probably totally irrelevant. In the satellite record, el ninos beginning in summer of a given year appear to have no discernible impact on September extent. The two strongest ones began in 1982 and 1997 - and the September extent even in those extreme years was well within the range of the years just before and just after it. I should also add that one of those years was above the linear trendline and the other was below it, but not significantly so.

I think it is safe to conclude that even a monster El nino starting this summer should have no detectable effect on September 2015 ice extent. It is safe to ignore it.
Title: Re: 2015 sea ice area and extent data
Post by: ChrisReynolds on July 02, 2015, 06:51:36 PM
Well the June figures for NSIDC extent are in, and at just 1.864 M km^2  its the smallest drop since 2004 which fell just over 1.2 M km^2.  At the time 2004 was the 9th lowest on record but by the end of the season it had dropped to 3rd lowest on record.

We didn't even get near the statistical 260 K anomalous drop that we normally see on July 1st.  The only  recent time we haven't seem this drop on July 1st it showed up on July 2nd so it will be interesting to see what  tomorrow brings.

All in all still an interesting season where anything can happen if the el Nino starts to  bite.

El nino is probably totally irrelevant. In the satellite record, el ninos beginning in summer of a given year appear to have no discernible impact on September extent. The two strongest ones began in 1982 and 1997 - and the September extent even in those extreme years was well within the range of the years just before and just after it. I should also add that one of those years was above the linear trendline and the other was below it, but not significantly so.

I think it is safe to conclude that even a monster El nino starting this summer should have no detectable effect on September 2015 ice extent. It is safe to ignore it.

It is rather a nice feeling to agree with you Nightvid, we seem to disagree on key issues rather a lot...

Take Curry 2004.
http://onlinelibrary.wiley.com/doi/10.1029/2004GL019858/full (http://onlinelibrary.wiley.com/doi/10.1029/2004GL019858/full)
ENSO has an effect, but it is not dominant.

Take NINO 3.4
http://www.esrl.noaa.gov/psd/gcos_wgsp/Timeseries/Nino34/ (http://www.esrl.noaa.gov/psd/gcos_wgsp/Timeseries/Nino34/)

Take NSIDC September extent.
ftp://sidads.colorado.edu/DATASETS/NOAA/G02135/Sep/N_09_area.txt (http://ftp://sidads.colorado.edu/DATASETS/NOAA/G02135/Sep/N_09_area.txt)

NSIDC extent has a strong trend, so I detrend using interannual difference of the September extent. This transforms the question to 'does June to August average NINO 3.4 have an relationship to the interannual difference of NSIDC September extent'. Doing a scatter plot and using a linear fit, the slope is -0.047, the R2 is 0.0015 (An R2 of 0 means no relationship, an R2 of 1 means a 1:1 correlation. So the slope is very slight, and the relationship is non existent.

If people think this isn't the right test they have the data, in the links above, but using such tests I have been unable to find any evidence of a relationship.

Tray another angle: Take NCEP/NCAR correlations from here:
http://www.esrl.noaa.gov/psd/data/correlation/ (http://www.esrl.noaa.gov/psd/data/correlation/)

NINO 3.4 is positive recently
https://www.ncdc.noaa.gov/teleconnections/enso/indicators/sst.php (https://www.ncdc.noaa.gov/teleconnections/enso/indicators/sst.php)
Only got up to May right now, but I presume the +ve phase has continued.

AO is positive recently.
http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/ao_index.html (http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/ao_index.html)

What does regression tell us?

See the attachments. Regression of ENSO is much smaller than for AO. AO suggets a negative regression over the Arctic Ocean (+ve AO index -> low pressure), ENSO suggests a positive regression over the Arctic Ocean (+ve NINO 3.4 -> high pressure).

Thus the NINO 3.4 index does not account for June's low pressure dominance over the Arctic Ocean.
Title: Re: 2015 sea ice area and extent data
Post by: wili on July 02, 2015, 07:52:25 PM
" el ninos beginning in summer of a given year appear to have no discernible impact on September extent."

That's true, but hasn't this El Nino been building for a lot longer than this summer?
Title: Re: 2015 sea ice area and extent data
Post by: Tor Bejnar on July 02, 2015, 09:11:10 PM
I think I remember reading somewhere that a strong El Niño during the northern hemisphere (NH) autumn or winter affects the following year's Arctic sea ice.  (Sometimes a La Niña is in place during the affected melting season.)  According to NOAA, we had a week El Niño last NH autumn/winter.  The effects of this now moderate (forecast by many to become strong) El Niño, if I remember correctly, wouldn't be felt until 2016.
Title: Re: 2015 sea ice area and extent data
Post by: ChrisReynolds on July 02, 2015, 10:54:45 PM
" el ninos beginning in summer of a given year appear to have no discernible impact on September extent."

That's true, but hasn't this El Nino been building for a lot longer than this summer?

You've got links to data, feel free to demonstrate it. :)
Title: Re: 2015 sea ice area and extent data
Post by: wili on July 03, 2015, 12:52:53 AM
I'm not sure there would be enough data to produce anything robust. How many week El Nino's have there been in August over the years?

Do you know if there's any support for Tor's claim?

ETA: This is what it says in the NSIDC FAQ page:
Quote
Lastly, the El Nino and La Nina cycle also appear to influence sea ice in the Pacific sector. El Nino patterns (a warm eastern tropical Pacific) are associated with warmer winds and less ice; the opposite is true for La Nina.

That is just talking about the 'Pacific sector' rather than the whole ice pack, and it doesn't say when in the year the El Nino occurs when it has even this limited effect. And it doesn't, unfortunately, link to any supporting study. More to search for...

http://nsidc.org/arcticseaicenews/faq/ (http://nsidc.org/arcticseaicenews/faq/)
Title: Re: 2015 sea ice area and extent data
Post by: LRC1962 on July 03, 2015, 03:47:53 AM
I do think there will be problems with any past studies of the enso effects on the Arctic as this will be the first time a change of El Nino/La Nina has occurred since the Terrible Troughs/Ridged Ridges has become a major influence in the North American weather pattern cycle.
Although things can change in a hurry, Southern Ontario has still seen generally cooler than normal temps given a warming world since January. This is indicative of troughs much more prevalent than ridges over that time span.
Title: Re: 2015 sea ice area and extent data
Post by: Tor Bejnar on July 03, 2015, 05:31:44 AM
What I remember having read might be this 2010 ASI blog post: Arctic sea ice melt: a correlation with ENSO? (http://neven1.typepad.com/blog/2010/06/a-correlation-.html)
Title: Re: 2015 sea ice area and extent data
Post by: ChrisReynolds on July 03, 2015, 11:21:31 AM
Tor,

Unfortunately things didn't pan out as suggested in that post. Wayne is reported as saying "If El-Nino persists till the spring, and La-Nina follows, ships at the Pole will wander unobstructed in August 2010." What happened was that the El Nino persisted through until the summer, with a La Nina in the autumn.
http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/ensostuff/ensoyears.shtml (http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/ensostuff/ensoyears.shtml)
So we will never know whether Wayne's anecdotal prediction was sound or not.

The major problem with that post though is that despite being entitled 'A correlation' there is a singular lack of mathematical correlation analysis using past data.

Wili,

Quote
I'm not sure there would be enough data to produce anything robust. How many week El Nino's have there been in August over the years?

Then ignore the neutral/weak states! Order in terms of most postive and most negative and see how much of the expected order of detrended September extent carries through that ordering process.

Or you could just look at Curry et al - They conclude that the ENSO and AO impact the ice 'greatly'. Yet with respect to the ENSO the impact found by Curry is really rather limited, the detail is the paragraph under figure 3.

Figure 4a shows the situation in Bering Sea and Alaska, with northward flow in El Nino years towards Beaufort & Chukchi. One could argue that this plays a role in the current Chukchi decline. True, extent in Chukchi is tracking close to 2007 and 2011. But in Beaufort extent continues to fall, after initial losses decline has arrested as the ice edge has hit the boundary of MYI (see HYCOM). And it is hard to seperate the impacts of the 10 June storm from the possible impact of El Nino in Chukchi. I should add that (from part of my upcoming June blog posts - the first half of June does show the expected northwards flow from the Pacific, but the second half does not).
Title: Re: 2015 sea ice area and extent data
Post by: DavidR on July 03, 2015, 12:01:18 PM
" el ninos beginning in summer of a given year appear to have no discernible impact on September extent."

That's true, but hasn't this El Nino been building for a lot longer than this summer?

You've got links to data, feel free to demonstrate it. :)
There are a number of indicators that the impact  of this El Nino may  be different  than previous ones.

1:  This year  the SOI has been reasonably  negative since August last  year:
http://www.bom.gov.au/climate/current/soihtm1.shtml (http://www.bom.gov.au/climate/current/soihtm1.shtml)
compared to  1982 and 1997  where it  was neutral or positive until the northern spring. 

2: the 1982 El Nino was impacted by the El Chichon volcanic eruption in April 1982 which would have reduced global temperature increases, however a record global temperature, and Sea Ice extent minimum occurred the following year.
https://en.wikipedia.org/wiki/El_Chichon (https://en.wikipedia.org/wiki/El_Chichon)

3. The Pacific Decadal Oscillation Index sat  above +2 for four months from December to  March this year:
http://research.jisao.washington.edu/pdo/PDO.latest (http://research.jisao.washington.edu/pdo/PDO.latest)
The last time this happened was June - Sept  1997; and every time it  has happened we have seen global temperature records in that year or the subsequent year.

So, given that all the precursors of significant warming were in  place from late last year, I  believe there is the possibility of significant impact this year.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on July 03, 2015, 04:17:33 PM
From yesterday's NSIDC data update I calculate the following CT updates (the days in this list are the days of data released, three days behind ice dates):

Fri       7.282727
Sat -177.7  7.105018
Sun -11.7  7.093290

Bad melt day (you know what I mean). About the only region with a decent decline is Laptev (-29k1). A few regions with small (~+10k) increases: CAB, ESS, Hudson and "Lakes".

In the attached NSIDC delta map, pixels with larger concentration changes than 7% or colored pinkish (down) or light blue (up). Solid red and blue are where the pixel concentration crosses the 15% limit (for extent).
Title: Re: 2015 sea ice area and extent data
Post by: Tor Bejnar on July 03, 2015, 04:37:56 PM
Thanks, Chris, for putting my remembered reading into perspective. 
Now, how do I erase that memory I've been holding on to for 4 years?! (I long for the interrobang!)
Title: Re: 2015 sea ice area and extent data
Post by: ChrisReynolds on July 03, 2015, 11:09:32 PM
Thanks, Chris, for putting my remembered reading into perspective. 
Now, how do I erase that memory I've been holding on to for 4 years?! (I long for the interrobang!)

Often when I answer even the simplest of questions it takes ages of digging to make sure I remembered it right.

David R,

Let's leave the thread to its proper purpose now. If you want to make a testable prediction based on your reasoning (sorry I don't find it at all persuasive) then you can evaluate it in September.
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on July 04, 2015, 03:45:37 PM
ADS-NIPR Extent:
9,341,259 km2 (03 July)
Down 4,600,801 km2 (33.%) from 2015 maximum of 13,942,060 km2 on 15 February.
6,163,804 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Down 46,395 km2 from previous day.
Down 476,460 km2 over past seven days (daily average: -68,066 km2).
Down 141,057 km2 for the month of July (daily average: -47,019 km2).
331,325 km2 below 2000s average for this date.
420,123 km2 above 2010s average for this date.
563,453 km2 above 2014 value for this date.
595,324 km2 above 2012 value for this date.
8th lowest July to-date average.
8th lowest value for the date.
64 days this year (34.78% year-to-date) have recorded the lowest daily extent.
32 days (17.39%) have recorded the second lowest.
32 days (17.39%) have recorded the third lowest.
128 days (69.57%) in total have been among the three lowest on record.


CT Area:
7,103,773 km2 (03 July [Day 0.5013])
Down 6,170,782 km2 (46.49%) from 2015 maximum of 13,274,555 km2 on 17 February [Day 0.1288].
4,869,764 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Down 178,954 km2 from previous day.
Down 729,672 km2 over past seven days (daily average: -104,239 km2).
Down 3,032,807 km2 for the month of July (daily average: -1,010,936 km2).
317,648 km2 below 2000s average for this date.
228,125 km2 above 2010s average for this date.
95,877 km2 below 2014 value for this date.
789,966 km2 above 2012 value for this date.
6th lowest July to-date average.
5th lowest value for the date.
7 days this year (3.8% year-to-date) have recorded the lowest daily area.
19 days (10.33%) have recorded the second lowest.
29 days (15.76%) have recorded the third lowest.
55 days in total (29.89%) have been among the lowest three on record.

Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on July 04, 2015, 04:56:45 PM
From yesterday's NSIDC data update I calculate the following CT updates (the days in this list are the days of data released, three days behind ice dates):

Sat       7.103773
Sun -11.7  7.092045
Mon -212.6  6.879408

Strong melt day follows a weak one reported on Sunday. Biggest decline in the CAB (-92k4), then Hudson (-61k9), ESS (-29k) and Laptev (-25k5).

In the attached NSIDC delta map, pixels with larger concentration changes than 7% or colored pinkish (down) or light blue (up). Solid red and blue are where the pixel concentration crosses the 15% limit (for extent).
Title: Re: 2015 sea ice area and extent data
Post by: oren on July 04, 2015, 05:21:51 PM
ADS-NIPR Extent:
9,341,259 km2 (03 July)
Down 4,600,801 km2 (33.%) from 2015 maximum of 13,942,060 km2 on 15 February.
6,163,804 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Down 46,395 km2 from previous day.
Down 476,460 km2 over past seven days (daily average: -68,066 km2).
Down 141,057 km2 for the month of July (daily average: -47,019 km2).
331,325 km2 below 2000s average for this date.
420,123 km2 above 2010s average for this date.
563,453 km2 above 2014 value for this date.
595,324 km2 above 2012 value for this date.
8th lowest July to-date average.
8th lowest value for the date.
64 days this year (34.78% year-to-date) have recorded the lowest daily extent.
32 days (17.39%) have recorded the second lowest.
32 days (17.39%) have recorded the third lowest.
128 days (69.57%) in total have been among the three lowest on record.


CT Area:
7,103,773 km2 (03 July [Day 0.5013])
Down 6,170,782 km2 (46.49%) from 2015 maximum of 13,274,555 km2 on 17 February [Day 0.1288].
4,869,764 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Down 178,954 km2 from previous day.
Down 729,672 km2 over past seven days (daily average: -104,239 km2).
Down 3,032,807 km2 for the month of July (daily average: -1,010,936 km2).
317,648 km2 below 2000s average for this date.
228,125 km2 above 2010s average for this date.
95,877 km2 below 2014 value for this date.
789,966 km2 above 2012 value for this date.
6th lowest July to-date average.
5th lowest value for the date.
7 days this year (3.8% year-to-date) have recorded the lowest daily area.
19 days (10.33%) have recorded the second lowest.
29 days (15.76%) have recorded the third lowest.
55 days in total (29.89%) have been among the lowest three on record.

There's an error in the area numbers July to date.
Title: Re: 2015 sea ice area and extent data
Post by: Neven on July 04, 2015, 06:42:16 PM
From yesterday's NSIDC data update I calculate the following CT updates (the days in this list are the days of data released, three days behind ice dates):

Sat       7.103773
Sun -11.7  7.092045
Mon -212.6  6.879408

Well well, a double century. That's going to make the CAPIE/compactness numbers even more interesting than they already are.
Title: Re: 2015 sea ice area and extent data
Post by: Buddy on July 04, 2015, 07:32:13 PM
Two months of interesting weather left....and July should prove to be the most interesting of all...

"The ice that remains, has been ravaged through the years,
As politicians spout convincing lies about how she is in fine shape,
But they cannot save the final crystals of the Arctic with their deception,
The truth lay in wait....for the final crystals to pass....and aye, they WILL pass."

"author unknown"
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on July 05, 2015, 03:30:31 PM
There's an error in the area numbers July to date.

Yes, thanks.

If you spot such errors in the future, please send a message directly to me. That will ensure the issue comes to my attention more quickly--and it will also ensure the error doesn't get copied and thus perpetuated in places I can't edit.

Thanks...
Title: Re: 2015 sea ice area and extent data
Post by: Nightvid Cole on July 05, 2015, 04:54:44 PM
" el ninos beginning in summer of a given year appear to have no discernible impact on September extent."

That's true, but hasn't this El Nino been building for a lot longer than this summer?

You've got links to data, feel free to demonstrate it. :)
There are a number of indicators that the impact  of this El Nino may  be different  than previous ones.

1:  This year  the SOI has been reasonably  negative since August last  year:
http://www.bom.gov.au/climate/current/soihtm1.shtml (http://www.bom.gov.au/climate/current/soihtm1.shtml)
compared to  1982 and 1997  where it  was neutral or positive until the northern spring. 

2: the 1982 El Nino was impacted by the El Chichon volcanic eruption in April 1982 which would have reduced global temperature increases, however a record global temperature, and Sea Ice extent minimum occurred the following year.
https://en.wikipedia.org/wiki/El_Chichon (https://en.wikipedia.org/wiki/El_Chichon)

3. The Pacific Decadal Oscillation Index sat  above +2 for four months from December to  March this year:
http://research.jisao.washington.edu/pdo/PDO.latest (http://research.jisao.washington.edu/pdo/PDO.latest)
The last time this happened was June - Sept  1997; and every time it  has happened we have seen global temperature records in that year or the subsequent year.

So, given that all the precursors of significant warming were in  place from late last year, I  believe there is the possibility of significant impact this year.

Arctic sea ice is only impacted by local forcing, not global temperatures. This forcing can include temperature, dew point, shortwave and longwave radiation (upwelling and downwelling), wind, sea surface temperature and salinity, waves, and other factors.

At the level of changes in climate, which take place over multidecadal and longer time scales, local temperatures and global temperatures are very tightly correlated, for both natural climate changes observable from paleoclimate data, and also from human-induced climate change which is easiest to observe in the records of the most recent decades (i.e. the 1980s and later).

However, when it comes to weather changes that cause year-to-year fluctuations in Arctic ice extent, area, and volume, there is no reason to presume a correlation with year-to-year global weather fluctuations.

 
Title: Re: 2015 sea ice area and extent data
Post by: BornFromTheVoid on July 05, 2015, 05:04:38 PM
Update for the week to July 4th

The current 5 day mean is on 9,860,000km2 while the 1 day extent is at 9,726,000km2.
The daily anomaly (compared to 81-10) is at -788,180km2, a decrease from -831,290km2 last week. The anomaly compared to the 07, 11 and 12 average is at +618,200km2, an increase from +299,000km2 last week. We're currently 8th lowest on record, down from 7th last week.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FHWiVcwI.png&hash=1e568dc0f7caabee0adfe0828547f5b9)

The average daily change over the last 7 days was -79.0k/day, compared to the long term average of -85.2k/day, and the 07, 11 and 12 average of -124.6k/day.
The average long term change over the next week is -80.5k/day, with the 07, 11, and 12 average being -115.8k/day.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2F0z3uWbk.png&hash=b10feba036b10cf96a16ae9d7c5ab016)

The loss so far this July is the 8th smallest on record. To achieve the largest monthly drop, a daily loss of at least 121.2k/day is required, while the smallest drop requires a loss of less than 65.4k/day and an average drop requires a loss of 89.7k/day.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FvqQD3bD.png&hash=5e15482444e205119b46d7fe1dd167f7)

The loss in June was the 18th smallest on record, while the average extent was the 4th smallest on record.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FMJBGnIC.png&hash=b595540e48c05c9b0cd9e8e613ff6eb1)

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2Fpot7nlP.png&hash=c0e93cdf1ed608b63e64c2c5630eb83c)
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on July 05, 2015, 05:52:05 PM
From yesterday's NSIDC data update I calculate the following CT updates (the days in this list are the days of data released, three days behind ice dates):

Sun       7.091670
Mon -212.6  6.879042
Tue -102.6  6.776474

Tuesday's century is supported by the following regions: CAB (-25k7), Greenland Sea (-20k3), ESS (-18k7), Laptev (-16k1) and Chukchi (-14k4). Opposition is by Beaufort (+23k3).

In the attached NSIDC delta map, pixels with larger concentration changes than 7% or colored pinkish (down) or light blue (up). Solid red and blue are where the pixel concentration crosses the 15% limit (for extent).
Title: Re: 2015 sea ice area and extent data
Post by: DavidR on July 06, 2015, 03:39:02 AM
Arctic sea ice is only impacted by local forcing, not global temperatures. This forcing can include temperature, dew point, shortwave and longwave radiation (upwelling and downwelling), wind, sea surface temperature and salinity, waves, and other factors.
NightVid,
My point was that there is insufficient evidence on the impact of major EL Ninos to rule an impact in or out this year.  The circumstances of the only two we have seen since 1979 were quite different from each other, and from this year, so any inferences of an impact or otherwise is purely  speculative.

SST and Air temperatures across the Arctic rebounded in June from the anomalously  low temperatures in May and if this continues for the next couple months we should return to a more dramatic melt than we have seen in the last month. An EL Nino could assist in raising these temperatures.
Title: Re: 2015 sea ice area and extent data
Post by: LRC1962 on July 06, 2015, 06:26:55 AM
Arctic sea ice is only impacted by local forcing, not global temperatures. This forcing can include temperature, dew point, shortwave and longwave radiation (upwelling and downwelling), wind, sea surface temperature and salinity, waves, and other factors.

At the level of changes in climate, which take place over multidecadal and longer time scales, local temperatures and global temperatures are very tightly correlated, for both natural climate changes observable from paleoclimate data, and also from human-induced climate change which is easiest to observe in the records of the most recent decades (i.e. the 1980s and later).

However, when it comes to weather changes that cause year-to-year fluctuations in Arctic ice extent, area, and volume, there is no reason to presume a correlation with year-to-year global weather fluctuations.
I have no clue where you get that idea from. Example: Jan - Mar there were a lot of cyclones that hit the Atlantic side of the Arctic. They did not start in the Arctic they got their start from the equatorial region of the Atlantic. To say they had no influence on the area/extent of the ice is nuts. To also say those storms and the frequency of them were not influenced by global temps is also nuts.
The Arctic is not an isolated insulated environment not affected by what is going on on a daily global scale is absolutely unbelievable otherwise we could weather forecast out to 2-3 months very accurately instead of 4-5 days.
Ice area and extent IMO are directly related to what happens on a global scale. The more local it becomes the greater the influence, but if the influence is big enough the effect on the ice even if the event is in Australia will change the ice in the Arctic.
Title: Re: 2015 sea ice area and extent data
Post by: plinius on July 06, 2015, 01:45:24 PM
I'd say a lot of your discrepancies appears to come from neglect of the non-linearities/feedbacks in the system. It is certainly true that most of the forcing/melt energy is coming from insolation and not atmospheric or oceanic heat advection. However, that's a bit of a short leap, isn't it? If you do not remove the snow cover first, albedo over the pack is so large that you keep your equilibrium temperature below 0 over most of the pack, so there will never be any serious melt if you do not initiate it. I think that's also one of the main reasons why ice climate models have had so many failures in correct predictions. Just don't cover the feedbacks on the ice properly.
Title: Re: 2015 sea ice area and extent data
Post by: Jim Hunt on July 06, 2015, 02:12:20 PM
Jan - Mar there were a lot of cyclones that hit the Atlantic side of the Arctic. They did not start in the Arctic they got their start from the equatorial region of the Atlantic. To say they had no influence on the area/extent of the ice is nuts.

I even made a video of all that pushing and shoving:

http://youtu.be/xmZkpURTJZs (http://youtu.be/xmZkpURTJZs)
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on July 06, 2015, 04:11:06 PM
From yesterday's NSIDC data update I calculate the following CT updates (the days in this list are the days of data released, three days behind ice dates):

Mon       6.878442
Tue -102.5  6.775924
Wed +39.2  6.815120

The largest increase since May 13, thanks to the CAB (+45k2) , Hudson (+27k2) and many regions with smaller increases. Declines in ESS (-29k3) and Chukchi (-25k1).

In the attached NSIDC delta map, pixels with larger concentration changes than 7% or colored pinkish (down) or light blue (up). Solid red and blue are where the pixel concentration crosses the 15% limit (for extent).
Title: Re: 2015 sea ice area and extent data
Post by: ghoti on July 06, 2015, 04:29:10 PM
Oh look! Toronto harbour is icing up again in time for the Climate Summit of the Americas :P

I really have trouble trusting all the data when the Great Lakes data keeps showing them icing up and melting while the temperatures hit 30C in July.

Oh well we don't seem to have a better source.
Title: Re: 2015 sea ice area and extent data
Post by: Nightvid Cole on July 06, 2015, 04:45:39 PM
LRC1962 and DavidR,

There is a lag of several months between El Nino region SST's and global temps; also, there's no evidence of correlation of detrended global temps with detrended Arctic temps over a relevant period (say, 1980-present or 1981-2010).

Yes, some mixing does occur, but so what? That could lead to a positive correlation, or it could lead to a negative correlation (since warm air going into the Arctic would be expected to occur simultaneously with cold air flowing out of the Arctic and thus reducing temperatures elsewhere), or, it could lead to a zero correlation.

You simply don't have any justification at all for inferring from year-to-year fluctuations of El Nino, PDO, or global temps to temps in the Arctic, except on a multidecadal (climate) basis.

The mere existence of atmospheric mixing does nothing to change that.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on July 06, 2015, 05:11:39 PM
Oh look! Toronto harbour is icing up again in time for the Climate Summit of the Americas :P

I really have trouble trusting all the data when the Great Lakes data keeps showing them icing up and melting while the temperatures hit 30C in July.

Oh well we don't seem to have a better source.

A repeat seems in order about lake ice.

CT-area and NSIDC extent are based on the same data, available as NSIDC gridded sea ice concentration data.

NSIDC does not include in its calculation ice detected in lakes, so there is no need to filter that says "No lake ice in July". In the ocean it _is_ filtered, so there will be "No ice in St. Lawrence" for example.

CT-area does include lake ice and also does not filter anything unless NSIDC has filtered it already.

This is only one of the deficiencies (my judgement) of the CT-area figures. But is a popular measure so I add some additional information about it. That is report it timely, summarize the regional deviations and note obvious "false" changes, like (dis)appearance of "lake ice".

Today's lake ice (and to be reported by CT on Wednesday) bumped +7k, which is under my radar.
Title: Re: 2015 sea ice area and extent data
Post by: oren on July 06, 2015, 05:14:16 PM
This melting season is wierd  :-\
Title: Re: 2015 sea ice area and extent data
Post by: LRC1962 on July 06, 2015, 05:36:49 PM
On the other hand is it at all possible to detrend what goes on in the Arctic with what goes on elsewhere? As I stated before and you have in no way denied, it is not an isolated environment.
You can not detrend the weather in England from what occurs in the Caribbean or what is happening in Greenland, they are all linked.
The extent in the Arctic is linked to the amount of snowfall on the ice, the SST of the Arctic, lows and highs, rainfall, wind direction, fires ..... all of which are governed far more by outside Arctic influences then by the Arctic itself especially in its current state. The problem science has is that the more chaotic things get the more trouble science has at defining what is important or how much each influence has importance. The less ASI you have the more chaotic everything becomes. The more chaotic thins become the less you can detrend anything because everything starts impacting everything else more and more.
Example: up to about 2000ish when you had a very high min extent, the jet stream was very fast smooth and very predictable. With that cam fairly predictable overall seasonal weather patterns. Now the jet stream wanders all over the place, seasonal weather patterns in any given geographical location have become more and more unusual, ocean currents are now starting to noticeably change etc.
BUT the greatest influences are no longer IMO based on multidecadal impacts, it is much more on the impacts of systems being sent into the Arctic that get their start far further away.
When a blocking high gets setup over Greenland systems get stuck over North America and systems in the Pacific then are tending to end up going into the Arctic. At the same time systems coming up the East coast of NA hit that high and either go west and push things north of Greenland into the Arctic or go east and because of a vacuum type effect end up going into the Arctic. These are not decadal systems these are just regular systems that always move around. The problem with that Greenland blocking high is that if the ice extent had been high it would have been located over the north pole. All this trying to say that you can no longer decouple the Arctic from the globe because chaos reigns supreme.

As Dr Barber and many others have stated. When they started studying the ASI is was boring because nothing happened, now things are changing so fast they have no clue what is going on and why.
Title: Re: 2015 sea ice area and extent data
Post by: seaicesailor on July 06, 2015, 05:48:05 PM
This melting season is wierd  :-\

I hear you
Title: Re: 2015 sea ice area and extent data
Post by: Nightvid Cole on July 06, 2015, 05:48:39 PM
On the other hand is it at all possible to detrend what goes on in the Arctic with what goes on elsewhere? As I stated before and you have in no way denied, it is not an isolated environment.
You can not detrend the weather in England from what occurs in the Caribbean or what is happening in Greenland, they are all linked.
The extent in the Arctic is linked to the amount of snowfall on the ice, the SST of the Arctic, lows and highs, rainfall, wind direction, fires ..... all of which are governed far more by outside Arctic influences then by the Arctic itself especially in its current state. The problem science has is that the more chaotic things get the more trouble science has at defining what is important or how much each influence has importance. The less ASI you have the more chaotic everything becomes. The more chaotic thins become the less you can detrend anything because everything starts impacting everything else more and more.
Example: up to about 2000ish when you had a very high min extent, the jet stream was very fast smooth and very predictable. With that cam fairly predictable overall seasonal weather patterns. Now the jet stream wanders all over the place, seasonal weather patterns in any given geographical location have become more and more unusual, ocean currents are now starting to noticeably change etc.
BUT the greatest influences are no longer IMO based on multidecadal impacts, it is much more on the impacts of systems being sent into the Arctic that get their start far further away.
When a blocking high gets setup over Greenland systems get stuck over North America and systems in the Pacific then are tending to end up going into the Arctic. At the same time systems coming up the East coast of NA hit that high and either go west and push things north of Greenland into the Arctic or go east and because of a vacuum type effect end up going into the Arctic. These are not decadal systems these are just regular systems that always move around. The problem with that Greenland blocking high is that if the ice extent had been high it would have been located over the north pole. All this trying to say that you can no longer decouple the Arctic from the globe because chaos reigns supreme.

I'll show you one example. Here is a plot of July-August temperatures averaged over the tropics, year by year:

http://www.esrl.noaa.gov/psd/cgi-bin/data/timeseries/timeseries.pl?ntype=1&var=Air+Temperature&level=2000&lat1=23.5&lat2=-23.5&lon1=0&lon2=360&iseas=1&mon1=6&mon2=7&iarea=1&typeout=2&Submit=Create+Timeseries (http://www.esrl.noaa.gov/psd/cgi-bin/data/timeseries/timeseries.pl?ntype=1&var=Air+Temperature&level=2000&lat1=23.5&lat2=-23.5&lon1=0&lon2=360&iseas=1&mon1=6&mon2=7&iarea=1&typeout=2&Submit=Create+Timeseries)

and here is the same for the Arctic:

http://www.esrl.noaa.gov/psd/cgi-bin/data/timeseries/timeseries.pl?ntype=1&var=Air+Temperature&level=2000&lat1=90&lat2=66.5&lon1=0&lon2=360&iseas=1&mon1=6&mon2=7&iarea=1&typeout=2&Submit=Create+Timeseries (http://www.esrl.noaa.gov/psd/cgi-bin/data/timeseries/timeseries.pl?ntype=1&var=Air+Temperature&level=2000&lat1=90&lat2=66.5&lon1=0&lon2=360&iseas=1&mon1=6&mon2=7&iarea=1&typeout=2&Submit=Create+Timeseries)

You can open them side by side in two browser windows and see that, apart from the overall warming trend, the individual warm/cool years in one series don't line up with those in the other series.
Title: Re: 2015 sea ice area and extent data
Post by: jdallen on July 06, 2015, 05:55:44 PM
From yesterday's NSIDC data update I calculate the following CT updates (the days in this list are the days of data released, three days behind ice dates):

Mon       6.878442
Tue -102.5  6.775924
Wed +39.2  6.815120

The largest increase since May 13, thanks to the CAB (+45k2) , Hudson (+27k2) and many regions with smaller increases. Declines in ESS (-29k3) and Chukchi (-25k1).

In the attached NSIDC delta map, pixels with larger concentration changes than 7% or colored pinkish (down) or light blue (up). Solid red and blue are where the pixel concentration crosses the 15% limit (for extent).
What's the granularity on CT again?  12.5KM?

It would be simply absurd to imagine that Wednesday increase is due to anything except for (1) sensors being fooled by surface conditions, (2) eccentricities of the algorithm or (3 - my favorite) ice breaking up at very small scales and spreading out.

(Edit: to my point - quick shot of detail around Wrangel island from yesterday.)
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on July 06, 2015, 06:31:33 PM
Quote
What's the granularity on CT again?  12.5KM?

Grid cell size (25x25km for CT and NSIDC) affects mostly extent. On area not so much and even less for the CT version (reason is the 0% cut-off applied in the algorithm, no ice is discarded when it just falls outside a particular grid cell).
Title: Re: 2015 sea ice area and extent data
Post by: Rubikscube on July 06, 2015, 06:55:40 PM
What's the granularity on CT again?  12.5KM?

It would be simply absurd to imagine that Wednesday increase is due to anything except for (1) sensors being fooled by surface conditions, (2) eccentricities of the algorithm or (3 - my favorite) ice breaking up at very small scales and spreading out.

(Edit: to my point - quick shot of detail around Wrangel island from yesterday.)

Considering the large drops during the last several days, it doesn't really seem that strange to have an uptick again, the maps Wipneus have been posting show that small upticks in concentration are quite usual, even on days with massive overall drops. It would be much stranger if ESS or Chukchi was gaining area again when these are the regions which are currently being pounded with heat, and it would be vary strange if this uptick is followed up by more slow days during this week.
Title: Re: 2015 sea ice area and extent data
Post by: Greenbelt on July 06, 2015, 11:04:37 PM
I wonder if strong winds from the north are expanding the ice pack toward Franz Josef land and Novaya Zemlya.  This could maybe have a similar impact as Fram export, expanding the ice extent at first, but reducing it over longer period of time.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on July 07, 2015, 04:09:57 PM
From yesterday's NSIDC data update I calculate the following CT updates (the days in this list are the days of data released, three days behind ice dates):

Tue       6.775785
Wed +39.4  6.815138
Thu -164.3  6.650875

Back to the big declines on Thursday. The big three are ESS (-33k3), Kara (-33k1) and CAB (-30k4), followed at some distance by Hudson (-20k8), Chukchi (-11k9) and CAA (-11k2).

In the attached NSIDC delta map, pixels with larger concentration changes than 7% or colored pinkish (down) or light blue (up). Solid red and blue are where the pixel concentration crosses the 15% limit (for extent).
Title: Re: 2015 sea ice area and extent data
Post by: seaicesailor on July 07, 2015, 04:22:01 PM
From yesterday's NSIDC data update I calculate the following CT updates (the days in this list are the days of data released, three days behind ice dates):

Tue       6.775785
Wed +39.4  6.815138
Thu -164.3  6.650875

Back to the big declines on Thursday. The big three are ESS (-33k3), Kara (-33k1) and CAB (-30k4), followed at some distance by Hudson (-20k8), Chukchi (-11k9) and CAA (-11k2).

In the attached NSIDC delta map, pixels with larger concentration changes than 7% or colored pinkish (down) or light blue (up). Solid red and blue are where the pixel concentration crosses the 15% limit (for extent).

Wipneus, allow me one question: the NSIDC map labeled with "July 6, 2015" reflects data of same time as the Uni-Bremen map labeled with "July 6, 2015" or is there some time offset? Thx.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on July 07, 2015, 04:39:05 PM

Wipneus, allow me one question: the NSIDC map labeled with "July 6, 2015" reflects data of same time as the Uni-Bremen map labeled with "July 6, 2015" or is there some time offset? Thx.

They are both of July 6. I assume that is from 0h00 UTC to 23h59 UTC, although that information is seldom mentioned.
Title: Re: 2015 sea ice area and extent data
Post by: seaicesailor on July 07, 2015, 04:45:13 PM

Wipneus, allow me one question: the NSIDC map labeled with "July 6, 2015" reflects data of same time as the Uni-Bremen map labeled with "July 6, 2015" or is there some time offset? Thx.

They are both of July 6. I assume that is from 0h00 UTC to 23h59 UTC, although that information is seldom mentioned.

Thank you.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on July 08, 2015, 06:03:25 PM
From yesterday's NSIDC data update I calculate the following CT updates (the days in this list are the days of data released, three days behind ice dates):

Wed       6.815259
Thu -164.0  6.651229
Fri -193.1  6.458162

The second century of how many? Actually without lake ice Friday (+11k8) would show a double century. Big area declines in Hudson (-55k2),  the CAB (-44k4), ESS (-43k6). Smaller declines (-13k - -18k) in Baffin, Beaufort, Kara and Chukchi. 

In the attached NSIDC delta map, pixels with larger concentration changes than 7% or colored pinkish (down) or light blue (up). Solid red and blue are where the pixel concentration crosses the 15% limit (for extent).
Title: Re: 2015 sea ice area and extent data
Post by: F.Tnioli on July 09, 2015, 12:26:09 PM
...
What's the granularity on CT again?  12.5KM?

It would be simply absurd to imagine that Wednesday increase is due to anything except for (1) sensors being fooled by surface conditions, (2) eccentricities of the algorithm or (3 - my favorite) ice breaking up at very small scales and spreading out.

(Edit: to my point - quick shot of detail around Wrangel island from yesterday.)
How about (4) - melt pond draining? Is my guess on it (http://forum.arctic-sea-ice.net/index.php/topic,1149.msg56070.html#msg56070) - of any much significance, you think?
Title: Re: 2015 sea ice area and extent data
Post by: Peter Ellis on July 09, 2015, 12:40:22 PM
Melt ponds come under (1) - surface conditions - surely?
Title: Re: 2015 sea ice area and extent data
Post by: F.Tnioli on July 09, 2015, 12:55:00 PM
Melt ponds come under (1) - surface conditions - surely?
Nope, not if draining is complete, at least. Imagine a melt pond on a large solid thick (1m+) plate of ice. Surface melt. Let's say it gets to some, say, 20cm depth at some point. Ok, sensors fooled, that's (1) alright - but fooled "back then", not "now". Imagine that during following melt - i.e. "now" - water "drills a hole" in the middle of the pond, right through the ice, possibly through some imperfections - this kind of thing we see all the time on top of Greenland ice sheet summer-time, nowadays. And then _whole_ pond - to very last gramm of water, - goes down through the hole and into the ocean. Then we still have that large solid not-so-thick-now, but still quite thick plate of ice, with a small hole in the middle which "collects" any further melt water immediatelly. End result: where was water surface before ("fooled sensors"), we now have ice surface, real physical change - increased ice area at this specific place.

Now how many of such plates are out there? Hundreds thousands square kilometers? I guess alot. And sometimes lots of them get "drained" during a single day, hence real thing, affecting albedo, melt mode, etc. Partial drains give partial effect, etc.

This way, it's "previous larger drops" which were a result of "surface conditions", - but not the recent +40k gain, which then would be a result of "disappearance of surface conditions" a.k.a. melt ponds. To me, that matters...
Title: Re: 2015 sea ice area and extent data
Post by: Peter Ellis on July 09, 2015, 01:15:19 PM
I think we're talking at cross purposes.  In your example, the apparent increase in area was not a real increase in area, precisely because the sensors were initially fooled by the presence of a melt pond.  That's clearly a subset of (1) in my view.
Title: Re: 2015 sea ice area and extent data
Post by: LRC1962 on July 09, 2015, 01:18:53 PM
Interesting article about melt ponds. http://www.pri.org/stories/2014-12-11/scientist-unlocks-one-mysteries-arctic-ice-melt (http://www.pri.org/stories/2014-12-11/scientist-unlocks-one-mysteries-arctic-ice-melt) .
Quote
Here's how: The second bucket was full of fresh water, the kind you get when snow melts, not salty sea water. Fresh water freezes at a higher temperature than salt water, so it solidifies inside those tiny cracks in the ice when sea water won’t.

It's Polashenski’s eureka moment: That’s why the ponds stick around.
Once the snow is gone and the melt water from it is gone, you would be then left for the most part, based on the fact most ice in the Arctic now young ice, with salty melt which can not collect into ponds. Also puts a lie to the fact that Arctic ice is solid.
Title: Re: 2015 sea ice area and extent data
Post by: Nightvid Cole on July 09, 2015, 01:54:29 PM
I doubt that draining melt ponds would cause the concentration to go up that much in any one place. A melt pond that has been there long enough to lose its fresh water would have also been there long enough to have a good shot at turning into an outright melt hole, especially on first-year ice. If this happens, the area not covered by ice is still there, only now in the form of a melt hole instead of a melt pond. On the other hand, if the ice disintegrates into much smaller floes and spreads to cover the surface again, then this could cause concentration to go up.

I would argue that a more plausible explanation for these upticks is clouds. Though thin clouds don't affect the lower-frequency SSMI/S sensor as easily as the higher-frequency AMSR2, thick clouds still do it.

I don't have time at the moment to show a series of images that makes it visually clear how to see the impact of clouds on the concentration maps, but suffice it to say that if you have a MODIS image of well-defined cloud bands over heavily ponded ice, and open a browser window side-by-side with a CT or Bremen map of the same day*, it will be obvious what's going on, with only cursory inspection.

*BEWARE of the delay in CT maps - the labeled date is incorrect, and the actual date lags by 2-3 days.
Title: Re: 2015 sea ice area and extent data
Post by: ghoti on July 09, 2015, 04:47:31 PM
I think the fact that these sensors continue to show ice forming and melting in the Great Lakes in July is proof enough that clouds are fooling them (and us). The temperatures range from 20C to 30C  when they show this new "ice".
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on July 09, 2015, 05:07:22 PM
From yesterday's NSIDC data update I calculate the following CT updates (the days in this list are the days of data released, three days behind ice dates):

Thu       6.650652
Fri -192.9  6.457797
Sat -89.5  6.368337

So a sub-century again on Saturday. Regionally the declines are much more modest: Baffin (-19k6), CAA (-19k), CAB (-18k) and Laptev (-11k9). The extent update in Chukchi (+28k1) is remarkable with a modest area decline of +7k8.

In the attached NSIDC delta map, pixels with larger concentration changes than 7% or colored pinkish (down) or light blue (up). Solid red and blue are where the pixel concentration crosses the 15% limit (for extent).
Title: Re: 2015 sea ice area and extent data
Post by: Peter Ellis on July 09, 2015, 05:12:49 PM
I doubt that draining melt ponds would cause the concentration to go up that much in any one place. A melt pond that has been there long enough to lose its fresh water would have also been there long enough to have a good shot at turning into an outright melt hole, especially on first-year ice.
Do you have a bath?  If so, how big is the plughole? You can drain an acre of melt pond through a 1 metre hole.

I would argue that a more plausible explanation for these upticks is clouds. Though thin clouds don't affect the lower-frequency SSMI/S sensor as easily as the higher-frequency AMSR2, thick clouds still do it.
Clouds, sun angle, satellite angle, temperature and other factors, as I said a few hours ago in the "2015 melting season" thread.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on July 09, 2015, 05:17:06 PM
I think the fact that these sensors continue to show ice forming and melting in the Great Lakes in July is proof enough that clouds are fooling them (and us). The temperatures range from 20C to 30C  when they show this new "ice".

You and I are having different ideas what proofs are.
The reason for false ice can be seen on all coasts and is called "land spillover". It is a well known effect caused by the large field of view of the SSMIS sensor and can be seen on all the coasts.

The false ice is of low concentration so the influence on area is also small (but not zero). On extent it is much larger (due to the 15% is counted as 100% effect), but wisely NSIDC does not include lake ice in their extent figures.

The AMSR2 sensor is superior in this respect.
Title: Re: 2015 sea ice area and extent data
Post by: Nightvid Cole on July 09, 2015, 06:03:52 PM
I doubt that draining melt ponds would cause the concentration to go up that much in any one place. A melt pond that has been there long enough to lose its fresh water would have also been there long enough to have a good shot at turning into an outright melt hole, especially on first-year ice.
Do you have a bath?  If so, how big is the plughole? You can drain an acre of melt pond through a 1 metre hole.


Ok, but if the effective freeboard of the bottom of the melt pond is negative, then even with a drain, some water will remain in the pond at gravitational fluid (isostatic) equilibrium.
Title: Re: 2015 sea ice area and extent data
Post by: ktonine on July 09, 2015, 06:05:29 PM
I think the fact that these sensors continue to show ice forming and melting in the Great Lakes in July is proof enough that clouds are fooling them (and us). The temperatures range from 20C to 30C  when they show this new "ice".

You and I are having different ideas what proofs are.
The reason for false ice can be seen on all coasts and is called "land spillover". It is a well known effect caused by the large field of view of the SSMIS sensor and can be seen on all the coasts.

The false ice is of low concentration so the influence on area is also small (but not zero). On extent it is much larger (due to the 15% is counted as 100% effect), but wisely NSIDC does not include lake ice in their extent figures.

The AMSR2 sensor is superior in this respect.

Instruments have uncertainties.  Some of this may be seen as bias and some as random fluctuations.  Understanding measurement uncertainty makes many of these seemingly 'strange' data values become nothing more than - well, what did you expect?

Given that the uncertainties in these measurements are relatively large, fluctuations - whether positive or negative - should just be ignored.  A single daily value should be ignored.  It's hard not to trumpet a double-century, but it has as much error in the measurement as the +46k number.  We DON'T KNOW the true value in either case.  We only know that the true value lies around the stated value plus or minus the measurement uncertainty - and even that is typically only true 95% of the time.

If we could place the earth into a stasis field and let the satellite circle around 1000 times and provide us 1000 measurements of the exact same arctic we would hope to see a normal distribution around the true value.  We would NOT get 1000 measurements with the same value - even though the sensors would be looking at the exact same earth each time.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on July 09, 2015, 07:07:44 PM

Instruments have uncertainties.  Some of this may be seen as bias and some as random fluctuations.  Understanding measurement uncertainty makes many of these seemingly 'strange' data values become nothing more than - well, what did you expect?


Really? I haven't seen anything strange despite the assertions made here. Near surface temperatures (T2m) are still hovering around zero and occasionally dipping below. Under such circumstances the ice surface dries quickly and that is having a exaggerated effect on NSIDC concentration. Call it measurement uncertainty, it is a known feature of the product.

Melt ponds? Most of what you see in the day to day changes is IMO the whetting/drying of the surface.

BTW the ADS-NIPR AMSR2 Jaxa thickness/melting map showed a simultaneous drop in melting area at the same day (ice date) that CT-area had the uptick. Different sensors, different microwave bands, different methods. That bump was real, no need for calling something strange, do not miss the opportunity to learn.
Title: Re: 2015 sea ice area and extent data
Post by: ktonine on July 09, 2015, 07:10:20 PM

Instruments have uncertainties.  Some of this may be seen as bias and some as random fluctuations.  Understanding measurement uncertainty makes many of these seemingly 'strange' data values become nothing more than - well, what did you expect?


Really? I haven't seen anything strange despite the assertions made here. ....

I haven't seen anything strange either - that's why strange is in quotation marks.
Title: Re: 2015 sea ice area and extent data
Post by: ktonine on July 09, 2015, 08:26:05 PM
Just to remember what we're dealing with:

Quote
In terms of absolute uncertainty of the algorithms, daily concentration errors of 5-10% are found within the ice pack during cold winter conditions. However, errors can be much higher in non-optimal conditions, such as near the ice edge and during surface melt conditions, and vary both spatially and temporally due to local conditions. Because of the low spatial resolution of the passive microwave sensors (footprints as large as 70 km for some frequencies), daily concentrations near ice edge may have errors of 50% or more; the low spatial resolution essentially limits the precision of the ice edge determination to ~25-50 km. Near the ice edge, concentration may be overestimated or underestimated depending on the sensor footprint location relative to the edge and the character of the ice at the edge (thin vs. thick, consolidated vs. loose). Within the ice pack, the passive microwave algorithms tend to underestimate concentration, especially in regions of thin ice and melting ice. Under strong surface melt conditions (including melt pond formation), concentrations may be underestimated by 20-30%. Extreme cold surface temperatures and atmospheric emission (primarily from thick clouds) tend to result in less extreme underestimations.

Obs4MIPs Sea Ice Concentration CDR Technical Note v3.1 (http://monitor.cicsnc.org/obs4MIPs/pdfs/Obs4MIPs%20Sea%20Ice%20Concentration%20CDR%20Technical%20Note%20v3.1.pdf)
Title: Re: 2015 sea ice area and extent data
Post by: seaicesailor on July 09, 2015, 09:01:23 PM

Instruments have uncertainties.  Some of this may be seen as bias and some as random fluctuations.  Understanding measurement uncertainty makes many of these seemingly 'strange' data values become nothing more than - well, what did you expect?


Really? I haven't seen anything strange despite the assertions made here. Near surface temperatures (T2m) are still hovering around zero and occasionally dipping below. Under such circumstances the ice surface dries quickly and that is having a exaggerated effect on NSIDC concentration. Call it measurement uncertainty, it is a known feature of the product.

Melt ponds? Most of what you see in the day to day changes is IMO the whetting/drying of the surface.

BTW the ADS-NIPR AMSR2 Jaxa thickness/melting map showed a simultaneous drop in melting area at the same day (ice date) that CT-area had the uptick. Different sensors, different microwave bands, different methods. That bump was real, no need for calling something strange, do not miss the opportunity to learn.
Chukchi extent increase is indeed strange. I wouldn't call it normal given current conditions.  8)
Title: Re: 2015 sea ice area and extent data
Post by: plinius on July 09, 2015, 09:18:55 PM
Indeed - would also like to point out that on the obuoy cameras you can even see a bit of frost extending into the little melt ponds... it's not always surface melt 24h/day, in particular not so far off the pole.
Title: Re: 2015 sea ice area and extent data
Post by: ktonine on July 09, 2015, 09:42:37 PM
Chukchi extent increase is indeed strange. I wouldn't call it normal given current conditions.  8)

The Chukchi has roughly extent of approximately 200k.  We see an uptick of 28k.  Is this strange or normal?

No.  The daily numbers have uncertainties that are likely 25% to 40% over the Chukchi at this point in the melt season.  I.e., the +28k probably has an uncertainty of anywhere from +/- 50k to +/- 80k.  So the 'true' value may well be -50k. 

Or the value from the day before may have been incorrect by -28k.  What we today is the 'true' value - meaning the number had to go up by +28k to correct for the previous number.

Bearing all this in mind a single day value increasing by 28k just simply is NOT surprising.  It doesn't matter whether you expect it to decline or not.  Math, statistics, and uncertainties simply dictate that you HAVE to see values like this.

Now, if we saw this for 5 days in a row - then I'd call it surprising.

Title: Re: 2015 sea ice area and extent data
Post by: Rubikscube on July 09, 2015, 10:30:37 PM
The Chukchi has roughly extent of approximately 200k.  We see an uptick of 28k.  Is this strange or normal?

No.  The daily numbers have uncertainties that are likely 25% to 40% over the Chukchi at this point in the melt season.  I.e., the +28k probably has an uncertainty of anywhere from +/- 50k to +/- 80k.  So the 'true' value may well be -50k. 

Or the value from the day before may have been incorrect by -28k.  What we today is the 'true' value - meaning the number had to go up by +28k to correct for the previous number.

Bearing all this in mind a single day value increasing by 28k just simply is NOT surprising.  It doesn't matter whether you expect it to decline or not.  Math, statistics, and uncertainties simply dictate that you HAVE to see values like this.

Now, if we saw this for 5 days in a row - then I'd call it surprising.

Totally agree.

What I find most puzzling right now is that surface melt at the O-buoys and the North pole cam doesn't seem to correlate at all with the respective 850 hPa temps. The melt ponds at the pole apparently stopped expanding just when the heat should really start to pound the ice. I was expecting to see several more drops in the 150k range, but I'm not so sure anymore.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on July 10, 2015, 08:02:11 AM

Chukchi extent increase is indeed strange. I wouldn't call it normal given current conditions.  8)

It is only strange because you do not think. Try it.

Hints:
- think what extent means
- think why extent is not area
- think why grid size matters for extent

If you cannot figure it out, or someone else explains it to you, I will explain later today or tomorrow.
Title: Re: 2015 sea ice area and extent data
Post by: seaicesailor on July 10, 2015, 08:59:53 AM

Chukchi extent increase is indeed strange. I wouldn't call it normal given current conditions.  8)

It is only strange because you do not think. Try it.


Wow thank you! That is right, I do think as a norm. Maybe I could read some literature too.  :)


Title: Re: 2015 sea ice area and extent data
Post by: Neven on July 10, 2015, 12:27:12 PM
For everyone who doesn't like to think (like me), just say to yourself: it all evens out, it all evens out, it all evens out.  ;D
Title: Re: 2015 sea ice area and extent data
Post by: anthropocene on July 10, 2015, 04:47:14 PM
The Chukchi has roughly extent of approximately 200k.  We see an uptick of 28k.  Is this strange or normal?

No.  The daily numbers have uncertainties that are likely 25% to 40% over the Chukchi at this point in the melt season.  I.e., the +28k probably has an uncertainty of anywhere from +/- 50k to +/- 80k.  So the 'true' value may well be -50k. 

Or the value from the day before may have been incorrect by -28k.  What we today is the 'true' value - meaning the number had to go up by +28k to correct for the previous number.

Bearing all this in mind a single day value increasing by 28k just simply is NOT surprising.  It doesn't matter whether you expect it to decline or not.  Math, statistics, and uncertainties simply dictate that you HAVE to see values like this.

Now, if we saw this for 5 days in a row - then I'd call it surprising.

Totally agree.

What I find most puzzling right now is that surface melt at the O-buoys and the North pole cam doesn't seem to correlate at all with the respective 850 hPa temps. The melt ponds at the pole apparently stopped expanding just when the heat should really start to pound the ice. I was expecting to see several more drops in the 150k range, but I'm not so sure anymore.
850hPa is approx. 1500m altitude. For melting sea-ice that heat may as well be on the moon. I'll ask a question: 850hPa is at temp x. Is the surface at higher, lower or the same temp as x?7
Title: Re: 2015 sea ice area and extent data
Post by: realitybytes on July 10, 2015, 05:25:02 PM
The Chukchi has roughly extent of approximately 200k.  We see an uptick of 28k.  Is this strange or normal?

No.  The daily numbers have uncertainties that are likely 25% to 40% over the Chukchi at this point in the melt season.  I.e., the +28k probably has an uncertainty of anywhere from +/- 50k to +/- 80k.  So the 'true' value may well be -50k. 

Or the value from the day before may have been incorrect by -28k.  What we today is the 'true' value - meaning the number had to go up by +28k to correct for the previous number.

Bearing all this in mind a single day value increasing by 28k just simply is NOT surprising.  It doesn't matter whether you expect it to decline or not.  Math, statistics, and uncertainties simply dictate that you HAVE to see values like this.

Now, if we saw this for 5 days in a row - then I'd call it surprising.

Totally agree.

What I find most puzzling right now is that surface melt at the O-buoys and the North pole cam doesn't seem to correlate at all with the respective 850 hPa temps. The melt ponds at the pole apparently stopped expanding just when the heat should really start to pound the ice. I was expecting to see several more drops in the 150k range, but I'm not so sure anymore.
850hPa is approx. 1500m altitude. For melting sea-ice that heat may as well be on the moon. I'll ask a question: 850hPa is at temp x. Is the surface at higher, lower or the same temp as x?7
Yes. ;)
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on July 10, 2015, 06:55:03 PM
From yesterday's NSIDC data update I calculate the following CT updates (the days in this list are the days of data released, three days behind ice dates):

Fri       6.458558
Sat -89.5  6.369031
Sun -113.4  6.255653

Sunday's century is brought to you by Baffin (-36k7). Also brought by Laptev (-22k), Greenlands Sea (-17k2), ESS (-16k3) and CAA (-15k5).

Today's puzzle is the ESS. The (CT) area drops by -16k, but (NSIDC) extent .... has an increase of a whopping +45k7 !

You can post your explanation below. I am not sure what the answer is myself, but "cannot be" is almost certainly incorrect.

In the attached NSIDC delta map, pixels with larger concentration changes than 7% or colored pinkish (down) or light blue (up). Solid red and blue are where the pixel concentration crosses the 15% limit (for extent).
Title: Re: 2015 sea ice area and extent data
Post by: nuwandaraalwis on July 10, 2015, 08:17:45 PM
So great predictions. Seems you have internal connection with CT today group ;) lol
Title: Re: 2015 sea ice area and extent data
Post by: plinius on July 10, 2015, 08:29:24 PM
Nasty week, lost >10% of the remaining area...
Title: Re: 2015 sea ice area and extent data
Post by: seaicesailor on July 10, 2015, 11:58:07 PM

I am not sure what the answer is myself, ...


Now, that is strange
 
Title: Re: 2015 sea ice area and extent data
Post by: Rubikscube on July 11, 2015, 01:25:09 AM
850hPa is approx. 1500m altitude. For melting sea-ice that heat may as well be on the moon. I'll ask a question: 850hPa is at temp x. Is the surface at higher, lower or the same temp as x?7

Duh? I dare to claim that the amount of heat in the 850 hPa layer is more relevant to the sea ice melt than the amount of heat on the moon. As for your question, the answer depends on whether the underlying surface is ocean, ice or land as well as a whole range of other conditions such as season, cloudiness, altitude and the list goes on. Thats in fact the entire point of the 850 hPa temps; that they are relatively unaffected by the local surface conditions, and thus can be used to distinguish warm and cold air masses. So when an extremely warm air mass engulfs virtually the entire CAB one should expect melt rates at the surface to pick up, and I suspect that the recent failure to do so may be related to cloud cover.
Title: Re: 2015 sea ice area and extent data
Post by: anthropocene on July 11, 2015, 09:31:51 AM
850hPa is approx. 1500m altitude. For melting sea-ice that heat may as well be on the moon. I'll ask a question: 850hPa is at temp x. Is the surface at higher, lower or the same temp as x?7

Duh? I dare to claim that the amount of heat in the 850 hPa layer is more relevant to the sea ice melt than the amount of heat on the moon. As for your question, the answer depends on whether the underlying surface is ocean, ice or land as well as a whole range of other conditions such as season, cloudiness, altitude and the list goes on. Thats in fact the entire point of the 850 hPa temps; that they are relatively unaffected by the local surface conditions, and thus can be used to distinguish warm and cold air masses. So when an extremely warm air mass engulfs virtually the entire CAB one should expect melt rates at the surface to pick up, and I suspect that the recent failure to do so may be related to cloud cover.

Thank you Rubikscube - I couldn't have put it better myself. To paraphrase - high temperatures at 850hPa MAY provide heat energy to the surface, there again they may not. Some on here seem to think that this is a given and so massive ice melt should automatically be the outcome of high 850hPa temps. When the measurements of the ice do not match this assumption then the measurements are  treated as suspicious. I'm just pointing out that a fault in this assumption is more likely to be the cause of the mismatch between expectation and actual behaviour than any measurement issues. 
(of course you are correct about the moon and 850hPa - I mentioned it to provoke thought about what is the difference between 850hPa and the moon and when this is at its greatest. ).
Title: Re: 2015 sea ice area and extent data
Post by: andy_t_roo on July 11, 2015, 10:28:51 AM
Today's puzzle is the ESS. The (CT) area drops by -16k, but (NSIDC) extent .... has an increase of a whopping +45k7 !

That looks like a diffusion / shift by wind for the ice; nullschool shows slow wind towards ess, but faster winds in ess towards the coast.

Could this be simple divergence of fragmented ice? -- unusual fluctuations in *area* would be unphysical, but extent is just the shuffling of the ice fragments; especially with the purple "lost concentration %" segment nearby, it looks like that ice just got shuffled into pixels which had a little under 15% ice last pass.
Title: Re: 2015 sea ice area and extent data
Post by: seaicesailor on July 11, 2015, 11:44:03 AM
Today's puzzle is the ESS. The (CT) area drops by -16k, but (NSIDC) extent .... has an increase of a whopping +45k7 !

That looks like a diffusion / shift by wind for the ice; nullschool shows slow wind towards ess, but faster winds in ess towards the coast.

Could this be simple divergence of fragmented ice? -- unusual fluctuations in *area* would be unphysical, but extent is just the shuffling of the ice fragments; especially with the purple "lost concentration %" segment nearby, it looks like that ice just got shuffled into pixels which had a little under 15% ice last pass.

Divergent drift toward the coast sounds reasonable since it would explain both concentration decrease and extent increase. However, note that the edge advance happens along a length of +1000 Km. A total of 45k km2 of extent increase means an average of 45000 / 1000 / 24 / 3600 * 100000 = 50 cm/s of mean drift during the day, which is very high!. HYCOM model however shows this

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fwww7320.nrlssc.navy.mil%2FhycomARC%2Fnavo%2Farcticicespddrf%2Fnowcast%2Ficespddrf2015071018_2015071000_040_arcticicespddrf.001.gif&hash=f5c6116c4ba0d6ae9c5cddcd790fa79b)

This model doesn't usually show drifts in the opposite direction than real.

So the reason must be another one. Another bump on the road, at least a nice exercise to keep us thinking a bit.

PS. Apparently it is been colder than previous days too, google "Wrangler island weather". Maybe just as much as to stop surface melting and cause some refreezing, just as much as to make some grid elements with <15% concentration become >15%? The edge is so spread that the number of grid elements on the verge of 15% may be pretty large.
Title: Re: 2015 sea ice area and extent data
Post by: seaicesailor on July 11, 2015, 12:45:24 PM

Chukchi extent increase is indeed strange. I wouldn't call it normal given current conditions.  8)

It is only strange because you do not think. Try it.

Hints:
- think what extent means
- think why extent is not area
- think why grid size matters for extent

If you cannot figure it out, or someone else explains it to you, I will explain later today or tomorrow.

It took me two days, sorry. I figured out a possible reason for these fluctuations. If not correct, yes please, explain it to me.
When compaction is low (and this year beats records) NSIDC extent numbers are particularly noisy, because the edge is less compact too, (wider, more spread) and there can be a very large number of grid elements close to 15% of concentration.
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on July 11, 2015, 02:44:41 PM
ADS-NIPR Extent:
8,660,819 km2 (10 July)
Down 5,281,241 km2 (37.88%) from 2015 maximum of 13,942,060 km2 on 15 February.
5,483,364 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Down 89,966 km2 from previous day.
Down 680,440 km2 over past seven days (daily average: -97,206 km2).
Down 821,497 km2 for the month of July (daily average: -82,150 km2).
446,956 km2 below 2000s average for this date.
434,103 km2 above 2010s average for this date.
524,857 km2 above 2014 value for this date.
684,247 km2 above 2012 value for this date.
8th lowest July to-date average.
8th lowest value for the date.
64 days this year (33.51% year-to-date) have recorded the lowest daily extent.
32 days (16.75%) have recorded the second lowest.
32 days (16.75%) have recorded the third lowest.
128 days (67.02%) in total have been among the three lowest on record.


CT Area:
6,369,842 km2 (10 July [Day 0.5205])
Down 6,904,714 km2 (52.01%) from 2015 maximum of 13,274,555 km2 on 17 February [Day 0.1288].
4,135,832 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Down 88,717 km2 from previous day.
Down 733,932 km2 over past seven days (daily average: -104,847 km2).
Down 1,084,979 km2 for the month of July (daily average: -108,498 km2).
467,909 km2 below 2000s average for this date.
117,015 km2 above 2010s average for this date.
222,131 km2 below 2014 value for this date.
454,264 km2 above 2012 value for this date.
5th lowest July to-date average.
5th lowest value for the date.
7 days this year (3.66% year-to-date) have recorded the lowest daily area.
19 days (9.95%) have recorded the second lowest.
29 days (15.18%) have recorded the third lowest.
55 days in total (28.8%) have been among the lowest three on record.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on July 11, 2015, 06:15:17 PM
From yesterday's NSIDC data update I calculate the following CT updates (the days in this list are the days of data released, three days behind ice dates):

Sat       6.369842
Sun -113.4  6.256430
Mon -100.0  6.156442

So Monday the chance of a century is exactly 50%. Supported by Hudson (-29k7), Laptev (-21k9), ESS (-16k3), CAB (-12k9) and Greenland Sea (-12k4). Baffin showed a small uptick (+11k7).

In the attached NSIDC delta map, pixels with larger concentration changes than 7% or colored pinkish (down) or light blue (up). Solid red and blue are where the pixel concentration crosses the 15% limit (for extent).
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on July 11, 2015, 07:32:35 PM


It took me two days, sorry. I figured out a possible reason for these fluctuations. If not correct, yes please, explain it to me.
When compaction is low (and this year beats records) NSIDC extent numbers are particularly noisy, because the edge is less compact too, (wider, more spread) and there can be a very large number of grid elements close to 15% of concentration.

Yes, maybe I can offer another way to look at it.

Assuming an exact algorithm, in an idealized sea ice measurement:

- infinite small grid cell and microwave field of view width;

  extent and are a are the same and compactness is always 100%.

When the grid is not infinitely fine, or the microwave field of view is wider than zero, extent will be larger than area depending how the ice is distributed: compact or a loose flotilla. But it will depend in the first place on the grid cell size/ microwave field of view.

NSIDC has the larger grid cell size 25km and an even bigger field of view of the microwave sensor (50km or so). That is one reason why NSIDC may behave strange now and than, stranger than the Uni Hamburg AMSR2 product that I use in the "home brew" thread. (The other reason is of course that exact algorithms do not exist.)
Title: Re: 2015 sea ice area and extent data
Post by: seaicesailor on July 11, 2015, 09:22:56 PM
Thank you
Title: Re: 2015 sea ice area and extent data
Post by: BornFromTheVoid on July 12, 2015, 04:44:29 PM
Update for the week to July 12th

The current 5 day mean is on 9,230,800km2 while the 1 day extent is at 9,013,000km2.
The daily anomaly (compared to 81-10) is at -854,100km2, an increase from -788,180km2 last week. The anomaly compared to the 07, 11 and 12 average is at +799,267km2, an increase from +618,200km2 last week. We're currently 9th lowest on record, down from 8th last week.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2F8TNlGwx.jpg&hash=8c756c2141ccb41ce8fe5eac59b77c43)

The average daily change over the last 7 days was -89.9k/day, compared to the long term average of -80.5k/day, and the 07, 11 and 12 average of -115.8k/day.
The average long term change over the next week is -85.9k/day, with the 07, 11, and 12 average being -107.9k/day.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FwecraJT.jpg&hash=030c44cae0fc8bd7504e62cfe554eabd)

The loss so far this July is the 15th largest on record. To achieve the largest monthly drop, a daily loss of at least 128.3k/day is required, while the smallest drop requires a loss of less than 53.0k/day and an average drop requires a loss of 85.8k/day.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2F3sYH9ao.jpg&hash=d06afcd2d03cc8ffec39ae7c503330b9)
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on July 12, 2015, 04:54:42 PM
From today's NSIDC data update I calculate the following CT updates (the days in this list are the days of data released, three days behind ice dates):

Sat       6.369842
Sun -113.4  6.256430
Mon -100.3  6.156095
Tue -118.6  6.037464

The respected members of this forum will be pleased to see the thirdfourth clean century in a row without wild excursions in either direction. That is on expense of the NSIDC extent of course, you cannot have it all.
Today's decline come from mostly from the CAB (-62k9). Much smaller (~ -10k) are declines in ESS, Hudson, Laptev, Beaufort, Baffin and "Lakes". The CAA increased by +14k.

Today's region that increased in extent and decreased in area is Hudson ( +27k9, -12k6)

In the attached NSIDC delta map, pixels with larger concentration changes than 7% or colored pinkish (down) or light blue (up). Solid red and blue are where the pixel concentration crosses the 15% limit (for extent).
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on July 13, 2015, 02:22:34 PM
ADS-NIPR Extent:
8,461,055 km2 (12 July)
Down 5,481,005 km2 (39.31%) from 2015 maximum of 13,942,060 km2 on 15 February.
5,283,600 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Down 86,828 km2 from previous day.
Down 748,022 km2 over past seven days (daily average: -106,860 km2).
Down 1,021,261 km2 for the month of July (daily average: -85,105 km2).
482,504 km2 below 2000s average for this date.
438,276 km2 above 2010s average for this date.
511,351 km2 above 2014 value for this date.
688,000 km2 above 2012 value for this date.
8th lowest July to-date average.
8th lowest value for the date.
64 days this year (33.16% year-to-date) have recorded the lowest daily extent.
32 days (16.58%) have recorded the second lowest.
32 days (16.58%) have recorded the third lowest.
128 days (66.32%) in total have been among the three lowest on record.


CT Area:
6,156,546 km2 (12 July [Day 0.526])
Down 7,118,010 km2 (53.62%) from 2015 maximum of 13,274,555 km2 on 17 February [Day 0.1288].
3,922,536 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Down 100,730 km2 from previous day.
Down 721,897 km2 over past seven days (daily average: -103,128 km2).
Down 1,298,275 km2 for the month of July (daily average: -108,190 km2).
509,609 km2 below 2000s average for this date.
74,223 km2 above 2010s average for this date.
301,967 km2 below 2014 value for this date.
558,373 km2 above 2012 value for this date.
5th lowest July to-date average.
5th lowest value for the date.
7 days this year (3.63% year-to-date) have recorded the lowest daily area.
19 days (9.84%) have recorded the second lowest.
29 days (15.03%) have recorded the third lowest.
55 days in total (28.5%) have been among the lowest three on record.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on July 13, 2015, 04:12:01 PM
From today's NSIDC data update I calculate the following CT updates (the days in this list are the days of data released, three days behind ice dates):

Mon       6.156546
Tue -118.9  6.037617
Wed -100.1  5.937527

So the fifth near century in a row. Drops in ESS, Beaufort, CAB, Greenland Sea and Laptev, about -20k each. An increase in the CAA (+17k).

Ghoti: Yes, there was a large drop in lake ice extent (-25k), but by area not so much (-7k).

In the attached NSIDC delta map, pixels with larger concentration changes than 7% or colored pinkish (down) or light blue (up). Solid red and blue are where the pixel concentration crosses the 15% limit (for extent).
Title: Re: 2015 sea ice area and extent data
Post by: seaicesailor on July 13, 2015, 04:29:54 PM

FWIW, NSIDC Extent fell 1,023,000 km2 for the last 10 days, averaging 100K per day.

Title: Re: 2015 sea ice area and extent data
Post by: ghoti on July 13, 2015, 04:37:58 PM
 :D Thanks for the mention Wipneus!

I also wonder about the numbers for the entire CAA given that the distances across most of the straits are less than the distances from shore to shore of the Great Lakes. Seems as if land edge problems might swamp the values for gain and loss of ice in the CAA.

Clearly it doesn't make much difference in the overall scheme of things since the total area there is small relative to the total ice area.
Title: Re: 2015 sea ice area and extent data
Post by: plinius on July 13, 2015, 05:20:15 PM
Honestly I think the curve for the CAA is pretty realistic, if you figure in melt ponds: Fast ice --> fast drop when melt ponds form --> recovery in the statistics when the ice surface collapses and melt ponds start to disappear --> melt-out.
http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/recent365.anom.region.12.html (http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/recent365.anom.region.12.html)

We are now in phase III for most of the archipelago.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on July 13, 2015, 05:47:27 PM
:D Thanks for the mention Wipneus!

I also wonder about the numbers for the entire CAA given that the distances across most of the straits are less than the distances from shore to shore of the Great Lakes. Seems as if land edge problems might swamp the values for gain and loss of ice in the CAA.


Indeed. Again this affects extent more than area, because the concentration of the false ice is less than 100% and it is mostly important when there is little real ice.

If you look at the regional extent graphs for NSIDC and Uni Hamburgs higher resolution SIC, you see that at minimum NSIDC saw more than two times as much ice extent in the CAA. The UH 2012 data where obtained by SSMIS, the AMSR2 instrument would have been a lot sharper still!

NSIDC:
https://sites.google.com/site/arctischepinguin/home/sea-ice-extent-area/grf/nsidc-nt-regional-extent-overview.png (https://sites.google.com/site/arctischepinguin/home/sea-ice-extent-area/grf/nsidc-nt-regional-extent-overview.png)
UH Hamburg:
https://sites.google.com/site/arctischepinguin/home/amsr2/grf/amsr2-extent-regional.png (https://sites.google.com/site/arctischepinguin/home/amsr2/grf/amsr2-extent-regional.png)




There was a little discuusion on the "home brew" thread last winter about ice in the Baltic that has the same problem:
http://forum.arctic-sea-ice.net/index.php/topic,382.0.html (http://forum.arctic-sea-ice.net/index.php/topic,382.0.html)


Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on July 14, 2015, 04:22:57 PM
From today's NSIDC data update I calculate the following CT updates (the days in this list are the days of data released, three days behind ice dates):

Tue       6.037754
Wed -100.2  5.937507
Thu -70.0  5.867492

So a sub-century on Thursday, lake ice is a factor as it jumped +20k1 (or CT's decision to include it in its sea ice area calculation).
Otherwise it is again the ESS and Laptev regions that do this: -38k5 and -36k7. Hudson declined -23k1, Beaufort -10k but CAA increased (again), now +29k7.

Laptev is the most remarkable region as regional extent dropped by a massive -83k9.

In the attached NSIDC delta map, pixels with larger concentration changes than 7% or colored pinkish (down) or light blue (up). Solid red and blue are where the pixel concentration crosses the 15% limit (for extent).
Title: Re: 2015 sea ice area and extent data
Post by: BornFromTheVoid on July 14, 2015, 06:39:57 PM
Using the NSIDC daily data, we've lost 905k in the last 7 days.

To put that into context, before 2007, only 8 different 7 day periods on the whole record saw a loss of greater than 900k, once in 1990, twice in 1991, twice in 1993, once in 1999 and twice in 2005.

In contrast, from 2007 to 2014 there have been 35 such losses
Title: Re: 2015 sea ice area and extent data
Post by: Peter Ellis on July 14, 2015, 07:04:19 PM
i.e. an average of ~4.5 per year.  So we need at least another three weeks similar to the current one for 2015 too keep up with the other post-2007 years.  Or do I misunderstand?

Edit:  If you're allowing overlapping periods, then I guess we'd only need another ~4 days of this rate of melt for 2015 to keep up with the other post-2007 years.
Title: Re: 2015 sea ice area and extent data
Post by: BornFromTheVoid on July 14, 2015, 07:26:11 PM
Yep, some overlap. Also, many get a boost from the land mask and algorithm changes that occur from June 30th to July 1st, which usually produces a loss of several 100k.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FqHn1ias.png&hash=714827895067301c8dad93f75532ab85)
Title: Re: 2015 sea ice area and extent data
Post by: BornFromTheVoid on July 14, 2015, 08:03:15 PM
Taking a look at the 81-10 anomalies (for 1st of April to 15th of September) rather than the absolute losses, we get this.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FwqNOso2.png&hash=859f104f2987ee545c16840c921a2695)

The recent 905k drop has an anomaly of just 340k, which doesn't seem like too much compared to the >700k anomalies 2012 had at the start of June.
Title: Re: 2015 sea ice area and extent data
Post by: jdallen on July 15, 2015, 02:15:42 AM
Gonna say this again.. Strip out Hudson and Baffin Bay, and 2015 is almost spot on 2012 area and extent numbers.

The qualitative difference between 2015 and the lowest three minimums is much less than the numbers might suggest.
Title: Re: 2015 sea ice area and extent data
Post by: Bob Wallace on July 15, 2015, 06:44:12 AM
Gonna say this again.. Strip out Hudson and Baffin Bay, and 2015 is almost spot on 2012 area and extent numbers.

The qualitative difference between 2015 and the lowest three minimums is much less than the numbers might suggest.

Those numbers are now being graphed and updated each day....

https://sites.google.com/site/arctischepinguin/home/amsr2/grf/basin-extent-multiprod.png

https://sites.google.com/site/arctischepinguin/home/amsr2/grf/basin-area-multiprod.png

Title: Re: 2015 sea ice area and extent data
Post by: jdallen on July 15, 2015, 07:45:38 AM
Gonna say this again.. Strip out Hudson and Baffin Bay, and 2015 is almost spot on 2012 area and extent numbers.

The qualitative difference between 2015 and the lowest three minimums is much less than the numbers might suggest.

Those numbers are now being graphed and updated each day....

https://sites.google.com/site/arctischepinguin/home/amsr2/grf/basin-extent-multiprod.png

https://sites.google.com/site/arctischepinguin/home/amsr2/grf/basin-area-multiprod.png
Thanks for the affirmation, Bob :)

I hadn't realized wipneus was updating these daily.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on July 15, 2015, 07:55:57 AM
Gonna say this again.. Strip out Hudson and Baffin Bay, and 2015 is almost spot on 2012 area and extent numbers.

The qualitative difference between 2015 and the lowest three minimums is much less than the numbers might suggest.

Those numbers are now being graphed and updated each day....

https://sites.google.com/site/arctischepinguin/home/amsr2/grf/basin-extent-multiprod.png

https://sites.google.com/site/arctischepinguin/home/amsr2/grf/basin-area-multiprod.png

Yup, at least twice daily actually. In the graphs we can see that the numbers for the restricted Basin are also close to those of 2013 and 2014. To finish near 2012's minimum, 2015 will still have to show something special in the remainder of the season.

For the moment the fact is that some peripherals have a big problem meeting the "normal" melt levels/rates.

Title: Re: 2015 sea ice area and extent data
Post by: Tor Bejnar on July 15, 2015, 02:33:36 PM
I wonder if (when?) these two graphs will show up on the ASIG Regional Graph page.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on July 15, 2015, 04:24:36 PM
From today's NSIDC data update I calculate the following CT updates (the days in this list are the days of data released, three days behind ice dates):

Tue       6.037754
Wed -100.2  5.937507
Thu -69.2  5.868299
Fri -131.6  5.736748

The fat century (helped by lakes dropping -10k) was supported  by CAB (-62k4), ESS (-27k5), Baffin (-18k), Beaufort (-17k6) and the CAA (-11k). Increases in area are the Laptev (+21k) and Greenland Sea(+13k4).

Crazy region of the day is Laptev with an increase in extent of +83k .

In the attached NSIDC delta map, pixels with larger concentration changes than 7% or colored pinkish (down) or light blue (up). Solid red and blue are where the pixel concentration crosses the 15% limit (for extent).
Title: Re: 2015 sea ice area and extent data
Post by: seaicesailor on July 15, 2015, 04:32:53 PM
Just as much as yesterday's extent decrease in Laptev.

Bizarre

 8)
Title: Re: 2015 sea ice area and extent data
Post by: jdallen on July 15, 2015, 05:58:47 PM
Just as much as yesterday's extent decrease in Laptev.

Bizarre

 8)
Looking at the 7/13 Wordview closeup of the area, I see the ice in the whole area is extremely rotten, and has been getting rain. It's so dark it's almost charcoal.  It will likely disappear shortly, for real, giving the numbers another bump.
Title: Re: 2015 sea ice area and extent data
Post by: Glenn Tamblyn on July 16, 2015, 04:22:57 AM
Although the main basin figures for 2012-15 (excluding the peripheral basins) still look similar, it is very much Chukchi  & ESS ahead counterbalanced by Beaufort behind with the Laptev catching up.

If the Chukchi/ESS continue on their current trend they will start to make inroads into the CAB sooner than previous years. The key seems to be the Beaufort. If the MYI there holds out, no chance of 2012. If it does melt out then even with little further penetration from the Beaufort into the CAB intrusion from the other basins should start to knock the CAB down.

Interestingly, CICE at DMI http://ocean.dmi.dk/anim/index.uk.php (http://ocean.dmi.dk/anim/index.uk.php) is showing a tongue of thinning ice from the Laptev all the way to the pole.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Focean.dmi.dk%2Fanim%2Fplots%2Fice.arc.121.png&hash=82d515f5b606e7dc5d7121e3032bd7f3)
The Bight may not have appeared on the surface yet but it may be forming beneath.
Title: Re: 2015 sea ice area and extent data
Post by: JayW on July 16, 2015, 11:30:04 AM
Although the main basin figures for 2012-15 (excluding the peripheral basins) still look similar, it is very much Chukchi  & ESS ahead counterbalanced by Beaufort behind with the Laptev catching up.

If the Chukchi/ESS continue on their current trend they will start to make inroads into the CAB sooner than previous years. The key seems to be the Beaufort. If the MYI there holds out, no chance of 2012. If it does melt out then even with little further penetration from the Beaufort into the CAB intrusion from the other basins should start to knock the CAB down.

Interestingly, CICE at DMI http://ocean.dmi.dk/anim/index.uk.php (http://ocean.dmi.dk/anim/index.uk.php) is showing a tongue of thinning ice from the Laptev all the way to the pole.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Focean.dmi.dk%2Fanim%2Fplots%2Fice.arc.121.png&hash=82d515f5b606e7dc5d7121e3032bd7f3)
The Bight may not have appeared on the surface yet but it may be forming beneath.

Wish I had seen this earlier, the June sea ice outlook from the national weather service in Anchorage. It was written June 25, I assume they will release a July outlook near the end of the month.   I'll just post a snippet to save space, for those interested in the whole outlook for the Chukchi and Beaufort, it's available here.
http://pafc.arh.noaa.gov/marfcst.php?fcst=FZAK30PAFC (http://pafc.arh.noaa.gov/marfcst.php?fcst=FZAK30PAFC)

Will be interesting to see how this area fares.

Quote
THE OFFSHORE REGION OF THE BEAUFORT SEA WILL CONTINUE TO BREAK UP
THROUGH SEPTEMBER. IT IS LIKELY THAT THE REGION FROM POINT BARROW TO
CAPE HALKETT NORTH TO 75N WILL NOT SEE ICE CONCENTRATIONS LESS THAN
3 TENTHS THIS SUMMER PERIOD
. THE OFFSHORE REGION FROM HARRISON BAY
TO FLAXMAN ISLAND NORTH TO 75N MAY SEE ICE CONCENTRATIONS DECREASE
TO 3 TENTHS BY THE END OF SEPTEMBER...AND THE OFFSHORE REGION FROM
FLAXMAN ISLAND TO DEMARCATION POINT NORTH TO 75N MAY SEE ICE
CONCENTRATIONS DECREASE TO 3 TENTHS BY THE END OF SEPTEMBER.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on July 16, 2015, 04:13:15 PM
From today's NSIDC data update I calculate the following CT updates (the days in this list are the days of data released, three days behind ice dates):

Wed       5.937680
Thu -69.2  5.868472
Fri -132.5  5.735944
Sat -119.7  5.616214

Saturdays century (despite +15k8 increase in lake "ice") has the support from the CAB (-42k8), ESS (-19k1), CAA (-17k) and Kara (-16k2).

In the attached NSIDC delta map, pixels with larger concentration changes than 7% or colored pinkish (down) or light blue (up). Solid red and blue are where the pixel concentration crosses the 15% limit (for extent).
Title: Re: 2015 sea ice area and extent data
Post by: OldLeatherneck on July 16, 2015, 04:34:33 PM
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi1269.photobucket.com%2Falbums%2Fjj597%2FOldLeatherNeck%2FArctic%2520sea%2520ice%2520extent%252015%2520July%25202015%2520_zpsyxh6s2fc.jpg&hash=23d512380a184d037a8cdb3efedb98f2)

At first look, it would appear that 2015 has only a slight chance of competing with 2007 and 2011 and no realistic path to approaching 2012's minimum.  My projections, from the current date use the average losses (2004 - 2014), average + 10%, average - 10%, as well as record minimum  and maximum losses for each  semi-monthly period.  I've stopped the projections on September 15th, because after that there is too much noise in the data to be meaningful.

Because there is still a significant amount of ice left in both the Hudson and Baffin bays, my projections are probably skewed somewhat high.  The general consensus is that these regions will be essentially ice-free by early September, if not sooner. Therefore, I'm not going to rule out having a minimum less that 2007 or 2011.

Setting a new record low SIE this year, will require maintaining near-record losses during the last half of July and first half of August, followed by new record losses in late August and/or early September.  Obviously, it will take ideal melt and transport conditions to prevail. 

If anyone finds this chart useful, I can post updates weekly, bi-weekly or never again.
Title: Re: 2015 sea ice area and extent data
Post by: jdallen on July 16, 2015, 06:12:03 PM
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi1269.photobucket.com%2Falbums%2Fjj597%2FOldLeatherNeck%2FArctic%2520sea%2520ice%2520extent%252015%2520July%25202015%2520_zpsyxh6s2fc.jpg&hash=23d512380a184d037a8cdb3efedb98f2)

At first look, it would appear that 2015 has only a slight chance of competing with 2007 and 2011 and no realistic path to approaching 2012's minimum.  My projections, from the current date use the average losses (2004 - 2014), average + 10%, average - 10%, as well as record minimum  and maximum losses for each  semi-monthly period.  I've stopped the projections on September 15th, because after that there is too much noise in the data to be meaningful.

Because there is still a significant amount of ice left in both the Hudson and Baffin bays, my projections are probably skewed somewhat high.  The general consensus is that these regions will be essentially ice-free by early September, if not sooner. Therefore, I'm not going to rule out having a minimum less that 2007 or 2011.

Setting a new record low SIE this year, will require maintaining near-record losses during the last half of July and first half of August, followed by new record losses in late August and/or early September.  Obviously, it will take ideal melt and transport conditions to prevail. 

If anyone finds this chart useful, I can post updates weekly, bi-weekly or never again.
would love to see more, OL.  Good to have you back.
Title: Re: 2015 sea ice area and extent data
Post by: carmiac on July 16, 2015, 07:40:04 PM
This is a great chart! Please keep it updated!
Title: Re: 2015 sea ice area and extent data
Post by: OldLeatherneck on July 17, 2015, 01:41:50 PM
would love to see more, OL.  Good to have you back.

jdalllen,

Thanks.  I'll keep the chart updated and post it on a weekly basis, +/_ a few days.

Yesterdays IJIS SIE loss was 155K.  The average daily loss for the last 16 days of July is about 87K, while the record loss was over 99K. 

In following the comments and charts on the 2015 Melting Season topic, it would appear that we are in for a week to ten days of significant melting.  The  question remains, how much of that will be seen in SIE loss. 
Title: Re: 2015 sea ice area and extent data
Post by: JayW on July 17, 2015, 03:35:56 PM
Wasn't sure of the best place to post this.  Feel free to move to a more appropriate location.  :)

Quote
Technical Implementation Notice 15-36
National Weather Service Headquarters Washington DC
330 PM EDT Fri Jul 10 2015
 
To:       Subscribers:
          -Family of Services
          -NOAA Weather Wire Service
          -Emergency Managers Weather Information Network
          -NOAAPORT
          Other NWS Partners, Users and Employees
 
From:     Timothy McClung
          Chief Operating Officer
          NWS Office of Science and Technology Integration
 
Subject:  Upgrade to Global-Real Time Ocean Forecast System
          (RTOFS) Effective September 1st, 2015
 
Effective on or about September 1, 2015
, beginning with the 0000
Coordinated Universal Time (UTC) run, the National Centers for
Environmental Prediction (NCEP) will upgrade the Global-RTOFS.
 
The system changes include:
 
- An increase in the number of vertical layers from 32 to 41
hybrid layers with additional iso-level coordinate layers in the
upper ~200m.
- The coupling of the ocean component Hybrid Coordinate Ocean
Model (HYCOM) to Los Alamos National Laboratory’s Community Sea
Ice (CICE) model using v4.0 of Earth System Modeling Framework
(ESMF).

- Updated bathymetry, which improves representation of grid
points in shallow regions where minimum depth is set to 5m.
- An update of the climatology from the U.S. Navy's Generalized
Digital Environmental Model (GDEM) v3.0 to v4.2.
- An equation of state, which is updated from 9 terms to 17
terms.
 
Benefits of the system changes include:
 
- Fine vertical resolution in the oceanic mixed layer with 9
additional near surface layers.
- Anticipated improvement to air-sea boundary flux for future
coupled applications (including hurricanes).
- Improved vertical coastal ocean resolution for downstream
applications, such as the National Ocean Service Operational
Forecast System (NOS-OFS) and Eco forecasting.
- Planned addition of Sea Ice products.
 
http://www.nws.noaa.gov/os/notification/tin15-36global-rtofs.htm (http://www.nws.noaa.gov/os/notification/tin15-36global-rtofs.htm)
Title: Re: 2015 sea ice area and extent data
Post by: seaicesailor on July 17, 2015, 04:25:17 PM
Not very fast, bumpy. But all in all, in the last 20 days, NSIDC sea ice extent has averaged slightly more than 100K Km2 of decrease per day. And the prospects are not good.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on July 18, 2015, 08:24:04 AM
From today's NSIDC data update I calculate the following CT updates (the days in this list are the days of data released, three days behind ice dates):

Wed       5.937680
Thu -69.2  5.868472
Fri -132.5  5.735944
Sat -119.9  5.616088
Sun -124.0  5.492084

Hudson and Baffin are the biggest contributors (-35k5 and -35k8) with  from the CAA (-24k3), Kara (-17k4). and "Lakes" (-15k5). The CAB shows a small increase (+12k3).

In the attached NSIDC delta map, pixels with larger concentration changes than 7% or colored pinkish (down) or light blue (up). Solid red and blue are where the pixel concentration crosses the 15% limit (for extent).
Title: Re: 2015 sea ice area and extent data
Post by: seaicesailor on July 18, 2015, 12:55:08 PM

The "piggy bank" Baffin&Hudson has decreased in size but still +400K-ish for extent and +300K-ish for area.

Title: Re: 2015 sea ice area and extent data
Post by: OldLeatherneck on July 18, 2015, 01:07:57 PM
IJIS SIE has lost 290K in just two days.  It will be interesting to see how many more century losses will occur before the end of July.

I know it's too early to get excited.......yet, this is exciting to watch.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on July 18, 2015, 01:35:07 PM
IJIS SIE has lost 290K in just two days.  It will be interesting to see how many more century losses will occur before the end of July.

I know it's too early to get excited.......yet, this is exciting to watch.

SIE, formerly known as IJIS, has a two day averaging. That means that yesterday's drop of 155053 km2 was actually a two-day drop of double that, or 310k. Can you already feel it in your stomach?
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on July 18, 2015, 03:02:42 PM
ADS-NIPR Extent:
7,920,694 km2 (17 July)
Down 6,021,366 km2 (43.19%) from 2015 maximum of 13,942,060 km2 on 15 February.
4,743,239 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Down 134,225 km2 from previous day.
Down 740,125 km2 over past seven days (daily average: -105,732 km2).
Down 1,561,622 km2 for the month of July (daily average: -91,860 km2).
597,762 km2 below 2000s average for this date.
341,630 km2 above 2010s average for this date.
343,629 km2 above 2014 value for this date.
546,647 km2 above 2012 value for this date.
8th lowest July to-date average.
7th lowest value for the date.
64 days this year (32.32% year-to-date) have recorded the lowest daily extent.
32 days (16.16%) have recorded the second lowest.
32 days (16.16%) have recorded the third lowest.
128 days (64.65%) in total have been among the three lowest on record.


CT Area:
NOTE: due to the extended absence of official CT sea ice area data, I've instead used Wipneus' calculated area numbers for the period from Days 0.5343 through 0.5397. The official numbers will be inserted if/when available. In the meantime, thanks, Wipneus!
5,616,088 km2 (17 July [Day 0.5397])
Down 7,658,467 km2 (57.69%) from 2015 maximum of 13,274,555 km2 on 17 February [Day 0.1288].
3,382,079 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Down 119,856 km2 from previous day.
Down 753,754 km2 over past seven days (daily average: -107,679 km2).
Down 1,838,733 km2 for the month of July (daily average: -108,161 km2).
612,221 km2 below 2000s average for this date.
66,984 km2 above 2010s average for this date.
247,782 km2 below 2014 value for this date.
579,155 km2 above 2012 value for this date.
5th lowest July to-date average.
5th lowest value for the date.
7 days this year (3.54% year-to-date) have recorded the lowest daily area.
19 days (9.6%) have recorded the second lowest.
29 days (14.65%) have recorded the third lowest.
55 days in total (27.78%) have been among the lowest three on record.
Title: Re: 2015 sea ice area and extent data
Post by: Vergent on July 18, 2015, 04:19:42 PM
NSIDC Daily Extent:

2015,    07,  14,      8.746,     
2015,    07,  15,      8.615,   -131k   
2015,    07,  16,      8.403,   -212k
2015,    07,  17,      8.271,   -132k

Three day loss: -475k
Three day average: -158k

Well, pigs aren't flying, but NSIDC is migrating south.

Verg
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on July 18, 2015, 04:31:14 PM
From today's NSIDC data update I calculate the following CT updates (the days in this list are the days of data released, three days behind ice dates):

Wed       5.937680
Thu -69.2  5.868472
Fri -132.5  5.735944
Sat -119.9  5.616088
Sun -124.3  5.491835
Mon -93.7  5.398108

Hudson, Laptev and CAA are the biggest decliners (~-18k). ESS and "lake ice" dropped -10k.

Baffin is the funny region with zero (CT) area change and an increase in (NSIDC) extent of +27k5.

In the attached NSIDC delta map, pixels with larger concentration changes than 7% or colored pinkish (down) or light blue (up). Solid red and blue are where the pixel concentration crosses the 15% limit (for extent).
Title: Re: 2015 sea ice area and extent data
Post by: OldLeatherneck on July 19, 2015, 12:30:55 PM
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi1269.photobucket.com%2Falbums%2Fjj597%2FOldLeatherNeck%2FArctic%2520sea%2520ice%2520extent%2520loss%2520scenarios%2520-%252018%2520July%25202015_zpshl6natzo.jpg&hash=34fa20842b7150f0f085a43e03547f99)

Considering the losses of the past few days and the current forecasts for the next week, I am willing to say that 2015 will almost certainly end up below 2013 and 2014.  I now also think that 2007 and 2011 are vulnerable, although it will still take favorable melt conditions for the remainder of the season. As to 2012, it's probably safe for now.

The big question is this; how rotten, mushy and slushy will the remaining ice be when this current attack of heat ends?
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on July 19, 2015, 02:11:41 PM
According to Wipneus's spot-on SIA numbers, 2015 area has now dropped below 1980's minimum of 5.5 million km2.  Next up: 1986.

If this year's SIA is going to make a serious run toward the bottom, now is the time. Beginning today, 2012 entered a 12-day run that saw just a single century drop, 2014 was a week away from the start of an overall one-week decrease of only 82k, and 2013 was less than a week away from kicking off a bizarre 10-day stretch which saw an overall increase of 21k.

Area will drop into 4th place tomorrow, leapfrogging over and ahead of 2010. This will be the first time 2015 SIA has been ranked higher than 5th place in over a month.

2015 is still 630k above 2012 for the date.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on July 19, 2015, 04:13:09 PM
From today's NSIDC data update I calculate the following CT updates (the days in this list are the days of data released, three days behind ice dates):

Wed       5.937680
Thu -69.2  5.868472
Fri -132.5  5.735944
Sat -119.9  5.616088
Sun -124.3  5.491835
Mon -93.7  5.398108
Tue -88.9  5.309186

With Tuesday's -89k the remarkable sequence of near one century drops is now numbered 11. This member came from Hudson (-22k8), Beaufort (-21k8) Laptev (-16k) and the ESS (-12k3). Baffin increased by +14k9.

In the attached NSIDC delta map, pixels with larger concentration changes than 7% or colored pinkish (down) or light blue (up). Solid red and blue are where the pixel concentration crosses the 15% limit (for extent).
Title: Re: 2015 sea ice area and extent data
Post by: BornFromTheVoid on July 19, 2015, 04:45:41 PM
Update for the week to July 18th

The current 5 day mean is on 8,431,000km2 while the 1 day extent is at 8,120,000km2.
The daily anomaly (compared to 81-10) is at -1,052,840km2, an increase from -854,100km2 last week. The anomaly compared to the 07, 11 and 12 average is at +754,867km2, a decrease from +799,267km2 last week. We're currently 7th lowest on record, up from 9th last week.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FdudeEjk.png&hash=4998c5fa9484ce67b1108dfbc0792397)

The average daily change over the last 7 days was -114.3k/day, compared to the long term average of -85.9k/day, and the 07, 11 and 12 average of -107.9k/day.
The average long term change over the next week is -89.0k/day, with the 07, 11, and 12 average being -80.2k/day.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FZRVTJ6D.png&hash=2c9149b73b7c2d1f1ff84d57ce45dc0f)

The loss so far this July is the 11th largest on record. To achieve the largest monthly drop, a daily loss of at least 135.8k/day is required, while the smallest drop requires a loss of less than 20.0k/day and an average drop requires a loss of 70.4k/day.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FS5RoxAF.png&hash=a16a556422c3e7e79dea3e220e4bd2f2)
Title: Re: 2015 sea ice area and extent data
Post by: Vergent on July 19, 2015, 05:55:57 PM
NSIDC Daily Extent:

2015,    07,  14,      8.746,     
2015,    07,  15,      8.615,   -131k   
2015,    07,  16,      8.403,   -212k
2015,    07,  17,      8.271,   -132k
2015,    07,  18,      8.120,   -151k

4 day loss 626k

Verg
Title: Re: 2015 sea ice area and extent data
Post by: Peter Ellis on July 19, 2015, 06:39:26 PM
From today's NSIDC data update I calculate the following CT updates (the days in this list are the days of data released, three days behind ice dates):

Wed       5.937680
Thu -69.2  5.868472
Fri -132.5  5.735944
Sat -119.9  5.616088
Sun -124.3  5.491835
Mon -93.7  5.398108
Tue -88.9  5.309186

With Tuesday's -89k the remarkable sequence of near one century drops is now numbered 11.

Uh, can you explain that?  Unless I'm misunderstanding, in order to get a sequence of 11 'near one century drops', you have to be including the -69.2 last Thursday.  If so, then this really is stretching the definition of 'near' to a ridiculous degree.

Notwithstanding all the excitable talk in this forum - as things stand, the July melt to date is somewhat lower than the average for the last decade.  June was the slowest melt month for many years.  In the absence of an unprecedented late July / early August collapse, this year will be another comparative squib, and end up no lower than 2010.
Title: Re: 2015 sea ice area and extent data
Post by: greatdying2 on July 19, 2015, 07:10:12 PM

With Tuesday's -89k the remarkable sequence of near one century drops is now numbered 11.

Uh, can you explain that?  Unless I'm misunderstanding, in order to get a sequence of 11 'near one century drops', you have to be including the -69.2 last Thursday.  If so, then this really is stretching the definition of 'near' to a ridiculous degree.

Perhaps he's excluding the increase in "lake ice", which stretches the definition of "real" to a ridiculous degree.

Quote from: Wipneus
So a sub-century on Thursday, lake ice is a factor as it jumped +20k1 (or CT's decision to include it in its sea ice area calculation).

Notwithstanding all the excitable talk in this forum - as things stand, the July melt to date is somewhat lower than the average for the last decade.  June was the slowest melt month for many years.  In the absence of an unprecedented late July / early August collapse, this year will be another comparative squib, and end up no lower than 2010.

Yes, I for one will be shocked when this year Baffin and Hudson continue their unprecedented collapse a few weeks later than usual (about 600 km2 left to go) ... shocked!   ::)

https://sites.google.com/site/arcticseaicegraphs/regional

(https://sites.google.com/site/arctischepinguin/home/amsr2/grf/basin-extent-multiprod.png)
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on July 19, 2015, 07:14:32 PM


Uh, can you explain that?  Unless I'm misunderstanding, in order to get a sequence of 11 'near one century drops', you have to be including the -69.2 last Thursday.  If so, then this really is stretching the definition of 'near' to a ridiculous degree.

I do mean it. In a time series where the day-to-day changes them selves often change more than a century the 40k is still "close". Add to this that we know that in the -69k was included a +20k jump in "lake ice", something I'd rather ignored.

Attached the day-to-day changes since end May. I looked for it today but there is no such series as the last 11 days to be found in 2012, 2013 or 2014 Arctic summers.
Title: Re: 2015 sea ice area and extent data
Post by: Peter Ellis on July 19, 2015, 08:44:59 PM
I looked for it today but there is no such series as the last 11 days to be found in 2012, 2013 or 2014 Arctic summers.

Can you explain the methodology by which you looked for it?

I took the complete data record from here:
http://arctic.atmos.uiuc.edu/cryosphere/timeseries.anom.1979-2008 (http://arctic.atmos.uiuc.edu/cryosphere/timeseries.anom.1979-2008)

Then appended the last 6 days as per your post here:
http://forum.arctic-sea-ice.net/index.php/topic,1112.msg57176.html#msg57176 (http://forum.arctic-sea-ice.net/index.php/topic,1112.msg57176.html#msg57176)

i.e the following values, which were not in the main source file from CT
5.868472
5.735944
5.616088
5.491835
5.398108
5.309186


For this file, I then simply calculated the total drop for each 11-day window up to the present day.
The last line of the file is thus:
2015.548     /     5.309186     /     -1.1493721
(i.e. date / current value / total drop over the preceding 11 days)

In the file as a whole, there are 494 cases where the aggregate drop over 11 days exceeds the most recent 11-day run.  If I restrict it to only 2012 onwards, there are still 80 11-day periods with a greater drop.

I have no idea what criteria you are using to make the current rate of area decrease stand out as in any way exceptional.
Title: Re: 2015 sea ice area and extent data
Post by: Peter Ellis on July 19, 2015, 08:55:55 PM
Next check - count the number of century breaks in each 11-day window.

(i.e. date / current value / total drop over the preceding 11 days / daily drop / number of century breaks in 11 days)

Filtering only the ones since 2010 with 9 or more centuries in 11 days - nothing unusual here for recent years.

2010.4795     /     7.3327947     /     -1.598886     /     -0.1868057     /     9
2010.4822     /     7.1141281     /     -1.7062216     /     -0.2186666     /     9
2010.485     /     7.0036221     /     -1.6926097     /     -0.110506     /     9
2010.4877     /     6.8817024     /     -1.5509939     /     -0.1219197     /     9
2010.4904     /     6.7840648     /     -1.6320424     /     -0.0976376     /     9
2010.4932     /     6.7720647     /     -1.6078153     /     -0.0120001     /     9
2012.4548     /     8.0299053     /     -1.7262392     /     -0.1740399     /     9
2012.4575     /     7.9473367     /     -1.769813     /     -0.0825686     /     9
2012.4603     /     7.7897234     /     -1.8719988     /     -0.1576133     /     10
2012.463     /     7.8461437     /     -1.6677141     /     0.0564203     /     9
2013.5096     /     6.8665686     /     -1.3926468     /     -0.1600747     /     9
2013.5452     /     5.3513508     /     -1.4234743     /     -0.1603718     /     9
2015.5425     /     5.491835     /     -1.323424     /     -0.124253     /     9

Title: Re: 2015 sea ice area and extent data
Post by: Peter Ellis on July 19, 2015, 09:05:08 PM
Final check: dropping the threshold to -85k to allow for "near centuries".

(i.e. date / current value / total drop over the preceding 11 days / daily drop / number of <-85k breaks in 11 days)

Filtering only the ones since 2010 with 9 or more <-85k breaks in 11 days - nothing unusual here for recent years.

2010.474     /     7.7280726     /     -1.3769956     /     -0.1562052     /     9
2010.4767     /     7.5196004     /     -1.4989695     /     -0.2084722     /     9
2010.4795     /     7.3327947     /     -1.598886     /     -0.1868057     /     9
2010.4822     /     7.1141281     /     -1.7062216     /     -0.2186666     /     9
2010.485     /     7.0036221     /     -1.6926097     /     -0.110506     /     9
2010.4877     /     6.8817024     /     -1.5509939     /     -0.1219197     /     9
2010.4904     /     6.7840648     /     -1.6320424     /     -0.0976376     /     10
2010.4932     /     6.7720647     /     -1.6078153     /     -0.0120001     /     10
2010.4958     /     6.7475667     /     -1.4625087     /     -0.024498     /     9
2011.5535     /     4.8431249     /     -1.1880912     /     -0.0875363     /     9
2011.5562     /     4.7263017     /     -1.258482     /     -0.1168232     /     10
2011.559     /     4.6315165     /     -1.2373094     /     -0.0947852     /     10
2011.5616     /     4.5535083     /     -1.1761851     /     -0.0780082     /     9
2011.5643     /     4.4520302     /     -1.1919308     /     -0.1014781     /     9
2012.4548     /     8.0299053     /     -1.7262392     /     -0.1740399     /     9
2012.4575     /     7.9473367     /     -1.769813     /     -0.0825686     /     9
2012.4603     /     7.7897234     /     -1.8719988     /     -0.1576133     /     10
2012.463     /     7.8461437     /     -1.6677141     /     0.0564203     /     9
2013.5096     /     6.8665686     /     -1.3926468     /     -0.1600747     /     9
2013.5452     /     5.3513508     /     -1.4234743     /     -0.1603718     /     9
2015.526     /     6.1565456     /     -1.2632199     /     -0.1007295     /     9
2015.5288     /     6.0377536     /     -1.2449732     /     -0.118792     /     9
2015.5315     /     5.9376798     /     -1.1660933     /     -0.1000738     /     9
2015.5343     /     5.868472     /     -1.2231976     /     -0.0692078     /     9
2015.537     /     5.735944     /     -1.1424983     /     -0.132528     /     9
2015.5397     /     5.616088     /     -1.1596974     /     -0.119856     /     9
2015.5425     /     5.491835     /     -1.323424     /     -0.124253     /     10
2015.5452     /     5.398108     /     -1.2525439     /     -0.093727     /     10
2015.548     /     5.309186     /     -1.1493721     /     -0.088922     /     10


The recent run in 2015 does seem to have extended a couple of days longer than the ones in 2011, 2012 and 2013, and is similar length the the one in 2010.  However, 2010, 2012 and even 2013 were associated with far higher total losses over 11 days.

So I guess the strongest comment the data actually justifies is that we have just had an unusually consistent run of melt days all either just under or just over a century, but that the actual rate of melt is not particularly unusual for the time of year - exactly what BFTV's post shows and what I originally commented on.
Title: Re: 2015 sea ice area and extent data
Post by: jdallen on July 19, 2015, 10:03:38 PM
Final check: dropping the threshold to -85k to allow for "near centuries".

(i.e. date / current value / total drop over the preceding 11 days / daily drop / number of <-85k breaks in 11 days)

<snippage>

The recent run in 2015 does seem to have extended a couple of days longer than the ones in 2011, 2012 and 2013, and is similar length the the one in 2010.  However, 2010, 2012 and even 2013 were associated with far higher total losses over 11 days.

So I guess the strongest comment the data actually justifies is that we have just had an unusually consistent run of melt days all either just under or just over a century, but that the actual rate of melt is not particularly unusual for the time of year - exactly what BFTV's post shows and what I originally commented on.

Let's also consider the numbers in this context - the years in question.  2010, 2011, 2012, which are in our bottom 5.  2013 *would* have been in the same category save for it's astonishing August "stall".

Let's also consider conditions.  IIRC, 2010-2012 had much different weather, with much higher levels of export.

Let's also consider ice; 2010 - 2013 all had significantly lower volume than 2015.

So, if you look at just the loss numbers, you don't get the full story.  I think it makes 2015's losses - with slower export, different weather, thicker ice - more remarkable in context.

I will also point out, irrespective of that, 2015's run puts it into the same league as 3 out of the bottom 5 minimums.  This could be interpreted as a very strong signal indicating this year is heading into competition with them, and quite possibly will displace them.
Title: Re: 2015 sea ice area and extent data
Post by: jdallen on July 20, 2015, 12:19:24 AM
Some number crunching using IJIS extent data.

I looked at how much melt took place for 2007-2013 from this date (July 19) through the year's annual minimum.

From that I derived rough Average and StdDev values for those values.

-2SDEV   2174266
-1SDEV   2686549
Average   3198831
+1SDEV   3711114
+2SDEV   4223396



Reducing the current IJIS extent (7767000) by those numbers, I get the following rough probabilities presuming melt conditions averaged over those years:

Prob  Extent
0.05   >5600000
0.11   5100000-5600000
0.34   4570000-5100000
0.34   4050000-4570000
0.11   3500000-4050000
0.05   < 3500000

So, given "average" behavior, reaching 2012 is a less than 5% probability.
Beating 2010 is above 50-50
Beating 2008 is about 50-50
Beating 2011 is above 1 chance in 6
Beating 2007 about 1 chance in 6

So,  I expect this year will make it into the top 5, probably the top 4, and still has very high probability of breaking into the top 3, especially when one considers the existing extra ice in the Hudson and Baffin, combined with the dipole forecast and continued high heat.  Those may actually persuade me to consider increasing my odds in favor of more melt by as much as 25%. 

The next week will tell me if my impressions of the weakness of ice in the eastern CAB and peripheral seas is correct, and persuades me to shift my expectations accordingly.

Title: Re: 2015 sea ice area and extent data
Post by: Peter Ellis on July 20, 2015, 12:29:00 AM
I will also point out, irrespective of that, 2015's run puts it into the same league as 3 out of the bottom 5 minimums.  This could be interpreted as a very strong signal indicating this year is heading into competition with them, and quite possibly will displace them.

Sorry I wasn't clear - when looking at century and near-century breaks, I only looked at 2010 onwards, since Wipneus said he'd looked at 2012, 2013 and 2014. I've edited my posts to clarify this.

If I extend the same comparison back further, you can find similar near-century runs in the summers of 2009, 2003,1999,1997,1995,1991,1986,1983, 1981 and 1979. Area and extent loss for this July to date are just not exceptional. Look at BFTV's post.  July losses are the 11th lowest on record (out of 36 years), and the 7th lowest in the last decade.  That is, only a little faster than the long-term average, and a little slower than most recent years.

I don't know how to put this more plainly.
Title: Re: 2015 sea ice area and extent data
Post by: slow wing on July 20, 2015, 01:22:06 AM
Peter,

  How many 11 day sequences were there where all 11 days had a drop of at least 69.2k km2?

  That is what Wipneus actually found to be remarkable.
Title: Re: 2015 sea ice area and extent data
Post by: jdallen on July 20, 2015, 02:49:40 AM
I will also point out, irrespective of that, 2015's run puts it into the same league as 3 out of the bottom 5 minimums.  This could be interpreted as a very strong signal indicating this year is heading into competition with them, and quite possibly will displace them.

Sorry I wasn't clear - when looking at century and near-century breaks, I only looked at 2010 onwards, since Wipneus said he'd looked at 2012, 2013 and 2014. I've edited my posts to clarify this.

If I extend the same comparison back further, you can find similar near-century runs in the summers of 2009, 2003,1999,1997,1995,1991,1986,1983, 1981 and 1979. Area and extent loss for this July to date are just not exceptional. Look at BFTV's post.  July losses are the 11th lowest on record (out of 36 years), and the 7th lowest in the last decade.  That is, only a little faster than the long-term average, and a little slower than most recent years.

I don't know how to put this more plainly.

I wasn't aware you'd stopped, but I'll trust your reporting on the numbers, so no, in that context it does not seem that unusual.

I think my follow up post pretty much summarizes my expectation for how things will go.  In it, I'm basing my extrapolation the heat budget, as exemplified by the melt numbers.
Title: Re: 2015 sea ice area and extent data
Post by: Peter Ellis on July 20, 2015, 09:41:54 AM
Peter,

  How many 11 day sequences were there where all 11 days had a drop of at least 69.2k km2?

  That is what Wipneus actually found to be remarkable.

1980, 1981, 1983, 1985, 1997, 2003, 2007, 2011, 2012, 2014 and 2015.
Title: Re: 2015 sea ice area and extent data
Post by: Peter Ellis on July 20, 2015, 10:33:41 AM
Most of the other similar drops have been a bit earlier in the year.  Shifting of it into July this year represents the slow June we had, and thus the ongoing contribution of Hudson Bay to the daily numbers.

Yes, it's true that having ~300k still "in the bank" in Hudson means that there's more pain stored up for later in this season.  However, the flip side of that is that if Hudson had melted out earlier, as expected, then the current daily values would be that much less impressive, with few recent centuries. 
Title: Re: 2015 sea ice area and extent data
Post by: DavidR on July 20, 2015, 11:52:22 AM
Most of the other similar drops have been a bit earlier in the year.  Shifting of it into July this year represents the slow June we had, and thus the ongoing contribution of Hudson Bay to the daily numbers.

Yes, it's true that having ~300k still "in the bank" in Hudson means that there's more pain stored up for later in this season.  However, the flip side of that is that if Hudson had melted out earlier, as expected, then the current daily values would be that much less impressive, with few recent centuries.
The Baffin/Hudson bank has only declined by a couple of hundred K km^2 in the last 10 days because the decline is normally  pretty high at this time.  So the extent decline over the past 10  days would still be near 1 M km^2.

This is still very much a tale of two areas the Canadian side of the Arctic is slow but starting to catch up. The Siberian side is well ahead of 2012 and shows no signs of slowing down. This is the areas where warmer waters will have the most  impact on the CAB.

The Beaufort now appears to be moving into a faster melting phase and the ice is very  broken up right up to the 80th parallel in that area. Melting in the Queen Elizabeth Islands also seems to be well ahead of the past couple of years, there is no snow on the islands themselves and the fracture in the ice north of the islands is more pronounced than in previous years.

In short the whole Arctic appears to  be primed for a lot  of melt throughout the next two months.  Although a record seems highly unlikely a minimum below 2007 remains a distinct possibility. 


Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on July 20, 2015, 03:25:56 PM

Can you explain the methodology by which you looked for it?


A  methodology to look at a graph ? Come on, you are looking for more than there is into this.


Quote
I have no idea what criteria you are using to make the current rate of area decrease stand out as in any way exceptional.

So in English the words remarkable and exceptional are synonymous? Perhaps it is my simple English but that is not what is meant.

I did choose the word "remarkable" with some care. I did not want to imply anything about significance. Instead I am in the process of trying to understand the day-to-day changes, using the different sources of information that are available each day. The CT-area path is mostly a rocky road, the eleven day smooth pause is noticeable (is that a better word?) enough.

So that is the second point where you missed my intended meaning: it is not the current rate but the constancy of it.

All in all, I always like to word things better when it causes misunderstandings and did so in the past. I am not sure how to have done it here, but am open to suggestions.
Title: Re: 2015 sea ice area and extent data
Post by: DavidR on July 20, 2015, 03:46:18 PM

Can you explain the methodology by which you looked for it?


A  methodology to look at a graph ? Come on, you are looking for more than there is into this.
Quote
I have no idea what criteria you are using to make the current rate of area decrease stand out as in any way exceptional.

So in English the words remarkable and exceptional are synonymous? Perhaps it is my simple English but that is not what is meant.

I did choose the word "remarkable" with some care. I did not want to imply anything about significance. Instead I am in the process of trying to understand the day-to-day changes, using the different sources of information that are available each day. The CT-area path is mostly a rocky road, the eleven day smooth pause is noticeable (is that a better word?) enough.

So that is the second point where you missed my intended meaning: it is not the current rate but the constancy of it.

All in all, I always like to word things better when it causes misunderstandings and did so in the past. I am not sure how to have done it here, but am open to suggestions.
Wipneus,
I think the word you want is 'noteworthy' it has the meaning  of being worth commenting on without necessarily being exceptional.

 I  had the same problem once when someone confused 'regularly' with 'frequently' the one implying  a pattern of behaviour while the other implied the number of times it occurred.  ???

Another whopping decline in NSIDC extent yesterday 188K km^2.   In the last 4 days that's 80 K per day closer to the lowest to date.
Title: Re: 2015 sea ice area and extent data
Post by: Greenbelt on July 20, 2015, 03:52:46 PM
Veering from data analysis toward numerology! :o

All statistical data gathering processes have quirks and flaws and we can read too much into the fine grains of any data stream that is subject to uncertainty, especially a daily one converting relatively crude sensor readings of a remote and inaccessible area of the planet from space!  It all evens out...
Title: Re: 2015 sea ice area and extent data
Post by: ktonine on July 20, 2015, 03:57:15 PM

So in English the words remarkable and exceptional are synonymous? Perhaps it is my simple English but that is not what is meant.

One should strive to be a 'charitable reader' - especially in dialogue where not all are native English speakers.  My initial reaction to the post was probably similar to Peter's, but I thought a little more and a 'charitable' reading of the post was that Wipneus chose to remark upon the numbers. That in itself made the numbers remarkable.  It's a tautology. 

As Wipneus points out 'remarkable' does not equal 'exceptional.'

DavidR - 'remarkable' comes from the French remarquer -- 'take note of'  :)


Title: Re: 2015 sea ice area and extent data
Post by: BornFromTheVoid on July 20, 2015, 04:05:57 PM
937k dropped in the last week on the daily NSIDC data.
If we drop just 186k over the next 2 days, we'll have yet another mega melt week (>1,000,000km2), the 5th year in a row to do so. This is especially impressive consider they occurred for just 2 years prior to 2007.
Title: Re: 2015 sea ice area and extent data
Post by: Vergent on July 20, 2015, 04:28:44 PM
Wipneus,

Quote
Note: snow cover data not updating ... we hope to have a new data source by July, 2015.

CT is going through a planned data source change. It may effect NSIDC as well. That may be the reason for the remarkable stability. You can see that the change effects concentration as well as snow by looking at the animation:

http://arctic.atmos.uiuc.edu/CT/animate.arctic.color.0.html (http://arctic.atmos.uiuc.edu/CT/animate.arctic.color.0.html)

Verg
Title: Re: 2015 sea ice area and extent data
Post by: jai mitchell on July 20, 2015, 04:39:54 PM
Charctic SIE loss today is 1.63 million Km^2
2012 loss for the same day was 1.004 million Km^2

http://nsidc.org/arcticseaicenews/charctic-interactive-sea-ice-graph/ (http://nsidc.org/arcticseaicenews/charctic-interactive-sea-ice-graph/)
Title: Re: 2015 sea ice area and extent data
Post by: Nightvid Cole on July 20, 2015, 04:41:25 PM
Wipneus,

Quote
Note: snow cover data not updating ... we hope to have a new data source by July, 2015.

CT is going through a planned data source change. It may effect NSIDC as well. That may be the reason for the remarkable stability. You can see that the change effects concentration as well as snow by looking at the animation:

http://arctic.atmos.uiuc.edu/CT/animate.arctic.color.0.html (http://arctic.atmos.uiuc.edu/CT/animate.arctic.color.0.html)

Verg

Could this be simply due to the 2-3 day lag "dropping out"?
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on July 20, 2015, 04:52:53 PM
From today's NSIDC data update I calculate the following CT updates (the days in this list are the days of data released, three days behind ice dates):

Sun       5.491770
Mon -93.7  5.398043
Tue -88.8  5.309246
Wed -115.6  5.193609

On Wednesday the discussed series will be twelve. Big decline in the Hudson (-40k8) followed by ESS (-20k9), Laptev (-18k4), CAB (-18k4) and CAA (-11k9).

Hudson did not just have a big drop in area, by extent (calculated the NSIDC way) the drop is -105k5.

In the attached NSIDC delta map, pixels with larger concentration changes than 7% or colored pinkish (down) or light blue (up). Solid red and blue are where the pixel concentration crosses the 15% limit (for extent).
Title: Re: 2015 sea ice area and extent data
Post by: OldLeatherneck on July 20, 2015, 04:54:28 PM

Can you explain the methodology by which you looked for it?


A  methodology to look at a graph ? Come on, you are looking for more than there is into this.


Quote
I have no idea what criteria you are using to make the current rate of area decrease stand out as in any way exceptional.

So in English the words remarkable and exceptional are synonymous? Perhaps it is my simple English but that is not what is meant.

I did choose the word "remarkable" with some care. I did not want to imply anything about significance. Instead I am in the process of trying to understand the day-to-day changes, using the different sources of information that are available each day. The CT-area path is mostly a rocky road, the eleven day smooth pause is noticeable (is that a better word?) enough.

So that is the second point where you missed my intended meaning: it is not the current rate but the constancy of it.

All in all, I always like to word things better when it causes misunderstandings and did so in the past. I am not sure how to have done it here, but am open to suggestions.

We are beginning to get obsessed with semantics.  What may be "exceptional" or "remarkable" to one person may be mundane to someone else.  We should remember that for many members of this Forum, English is a second or third language.  Even among native English speakers there are significant semantic differences between countries and regions within a given country.  I found  this to be true when I had the opportunities to work with the British and Australian navies.

I have the utmost respect for the massive efforts Wipneus has made to both the Forum and the Blog.  His charts, graphs and animations have been "Exceptionally" valuable learning tools for each of us.  His choice of adjectives and adverbs is entirely up to him.

This thread is not about "Scientific Technical Writing 101"
Title: Re: 2015 sea ice area and extent data
Post by: Nightvid Cole on July 20, 2015, 05:00:18 PM
Charctic SIE loss today is 1.63 million Km^2
2012 loss for the same day was 1.004 million Km^2

http://nsidc.org/arcticseaicenews/charctic-interactive-sea-ice-graph/ (http://nsidc.org/arcticseaicenews/charctic-interactive-sea-ice-graph/)

I think you need to move the decimal point one spot to the left...
Title: Re: 2015 sea ice area and extent data
Post by: Vergent on July 20, 2015, 05:15:52 PM
NSIDC Daily Extent:

2015,    07,  14,      8.746,
2015,    07,  15,      8.615,   -131k   
2015,    07,  16,      8.403,   -212k
2015,    07,  17,      8.271,   -132k
2015,    07,  18,      8.120,   -151k
2015,    07,  19,      7.932,   -188k

5 day loss: 814K, averaging -162/day. Climatology ('79 to 2010) for 7/14-7/19 is -461k

For reference 2012:

2012,    07,  14,      7.868..............2015,    07,  14,      8.746, ...................+878k   
2012,    07,  15,      7.705,  -163k....2015,    07,  15,      8.615,   -131k
2012,    07,  16,      7.606,   -99k.....2015,    07,  16,      8.403,   -212k
2012,    07,  17,      7.481,  -125k....2015,    07,  17,      8.271,   -132k
2012,    07,  18,      7.420,   -61k.....2015,    07,  18,      8.120,   -151k
2012,    07,  19,      7.350,   -70k.....2015,    07,  19,      7.932,   -188k..........+582
2012,    07,  20,      7.340,   -10k
2012,    07,  21,      7.297,  -113k
2012,    07,  22,      7.184,  -113k
2012,    07,  23,      7.118,   -66k
2012,    07,  24,      7.035,   -83k
2012,    07,  25,      6.931,  -104k
2012,    07,  26,      6.809,  -122k
2012,    07,  27,      6.677,  -132k
2012,    07,  28,      6.600,   -77k
2012,    07,  29,      6.478,  -122k
2012,    07,  30,      6.400,   -78k
2012,    07,  31,      6.368,   -32k

The 2012 lead is evaporating, er, melting. 2015 caught up by 296k in 5 days.

Verg

Edit: Tomorrow,....I see some low hanging fruit.
Title: Re: 2015 sea ice area and extent data
Post by: Neven on July 20, 2015, 05:42:29 PM
July 2015 saw 14 century breaks in 20 days. 2013 comes close with 13 century breaks, but in my spreadsheet all the other years in the 2006-2015 period saw 11 century breaks or less. 2012, for instance, saw 8 century breaks.
Title: Re: 2015 sea ice area and extent data
Post by: Andir on July 20, 2015, 06:20:21 PM
I think in two or three days the hudson/ baffin effect  will be over. Is there another "delayed melt effect this year or will the melt numbers will slow down a bit?
Title: Re: 2015 sea ice area and extent data
Post by: jdallen on July 20, 2015, 06:25:05 PM
I think in two or three days the hudson/ baffin effect  will be over. Is there another "delayed melt effect this year or will the melt numbers will slow down a bit?
Good question. It depends on the state of the remaining ice.  To that point, there are huge areas of very vulnerable ice - near or over 2 million km2 - outside of the CAB. 

It may slow down, but that slowdown might be a drop from 125,000 km2 a day to 100,000 km2 a day...
Title: Re: 2015 sea ice area and extent data
Post by: jai mitchell on July 20, 2015, 07:04:10 PM
or it might speed up.
Title: Re: 2015 sea ice area and extent data
Post by: OldLeatherneck on July 20, 2015, 09:23:25 PM
Mea Culpa Time!!

It's never fun to admit having made a substantial mistake, particularly when it is in something you have made public.  When I first built my SIE models last spring, somehow I erroneously entered the wrong value for the Record MAX Loss for the latter half of August, by an amount in excess of ~400K. Therefore, my charts and tables wrongly indicated that there was some small chance of catching 2012 values this year.  My apologies to everyone for the mistake. Please note that any plots or results using average values for each period were correct. I'll assign the mistake to one of the following:

Partial vision in one eye
Attention Deficit Disorder
Lack of due diligence
The aging process
 
Here are corrected versions of both the chart and the table.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi1269.photobucket.com%2Falbums%2Fjj597%2FOldLeatherNeck%2FADR-NIPR%2520Arctic%2520sea%2520ice%2520extent%252019%2520July%25202015%2520Power%2520point_zpshiwypaqd.jpg&hash=af67eb452cd9201a3f96c1c96a3dbcdf)

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi1269.photobucket.com%2Falbums%2Fjj597%2FOldLeatherNeck%2FADR-NIPR%2520Arctic%2520sea%2520ice%2520projections%252019%2520July%25202015%2520_zpsri2enirm.jpg&hash=0620944ded8e098f481e11406ba979e2)
Title: Re: 2015 sea ice area and extent data
Post by: oren on July 21, 2015, 01:54:57 AM

We are beginning to get obsessed with semantics.  What may be "exceptional" or "remarkable" to one person may be mundane to someone else.  We should remember that for many members of this Forum, English is a second or third language.  Even among native English speakers there are significant semantic differences between countries and regions within a given country.  I found  this to be true when I had the opportunities to work with the British and Australian navies.

I have the utmost respect for the massive efforts Wipneus has made to both the Forum and the Blog.  His charts, graphs and animations have been "Exceptionally" valuable learning tools for each of us.  His choice of adjectives and adverbs is entirely up to him.

This thread is not about "Scientific Technical Writing 101"

Thank you!
Title: Re: 2015 sea ice area and extent data
Post by: TeaPotty on July 21, 2015, 02:22:56 AM
I just want to chime in and also thank the tireless Wipneus  ;D
Title: Re: 2015 sea ice area and extent data
Post by: greatdying2 on July 21, 2015, 03:52:23 AM
Quote
I have no idea what criteria you are using to make the current rate of area decrease stand out as in any way exceptional.

So in English the words remarkable and exceptional are synonymous? Perhaps it is my simple English but that is not what is meant.

Wipneus, your use of the word remarkable is entirely correct: it means, "worthy of attention."

Edit: Catching up on more recent messages, I see this point has perhaps already been made.

P.S. I am a native english speaker.

P.P.S. You rock! :)
Title: Re: 2015 sea ice area and extent data
Post by: greatdying2 on July 21, 2015, 04:19:47 AM
I think in two or three days the hudson/ baffin effect  will be over. Is there another "delayed melt effect this year or will the melt numbers will slow down a bit?
Good question. It depends on the state of the remaining ice.  To that point, there are huge areas of very vulnerable ice - near or over 2 million km2 - outside of the CAB. 

It may slow down, but that slowdown might be a drop from 125,000 km2 a day to 100,000 km2 a day...

Hudson and Baffin combined have about 400 km2 area remaining, and a bit more than that in extent. If this all goes within 2-3 days, they'll be amazing days! To me it looks more like, if the current rates of decline continue, yes perhaps Hudson will be gone within a few days but Baffin will last for a couple more weeks.

I nevertheless agree with what I think is perhaps your underlying message: that these areas were always going to completely melt out (albeit late, throwing all kinds of wrenches in comparisons of overall melt amounts for particular time periods...). What actually matters is better represented for example in the following graphs, which suggest that like 2012, this year may be starting to diverge from the last two years in area and extent measures (thanks yet again to Wipneus). The next couple of weeks will be key, and it seems the weather this week at least is forecast to be conducive to higher than normal reductions.

https://sites.google.com/site/arctischepinguin/home/amsr2/grf/basin-area-multiprod.png
https://sites.google.com/site/arctischepinguin/home/amsr2/grf/basin-extent-multiprod.png
Title: Re: 2015 sea ice area and extent data
Post by: Andir on July 21, 2015, 07:54:48 AM
Thank you for wipneus links. And you are right. There are still 400 km2 remaining in Hudson/baffin area. But if u look to former years, the last 100 km2 for each region disapearing slowly with some rebounds. So i think, we can only see max. 200 km2 of fast melt. Perhaps it will take longer for baffin, so the effect gets even smaller the next days for these regions.
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on July 21, 2015, 02:09:38 PM
ADS-NIPR Extent:
7,522,508 km2 (20 July)
Down 6,419,552 km2 (46.04%) from 2015 maximum of 13,942,060 km2 on 15 February.
4,345,053 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Down 139,308 km2 from previous day.
Down 813,073 km2 over past seven days (daily average: -116,153 km2).
Down 1,959,808 km2 for the month of July (daily average: -97,990 km2).
713,856 km2 below 2000s average for this date.
177,611 km2 above 2010s average for this date.
32,792 km2 above 2014 value for this date.
365,712 km2 above 2012 value for this date.
8th lowest July to-date average.
6th lowest value for the date.
64 days this year (31.84% year-to-date) have recorded the lowest daily extent.
32 days (15.92%) have recorded the second lowest.
32 days (15.92%) have recorded the third lowest.
128 days (63.68%) in total have been among the three lowest on record.


CT Area:
NOTE: due to inconsistent updates of official CT sea ice area data, I'll be using a combination of those official data and Wipneus' calculated area numbers. The official numbers will be inserted as they become available.
5,193,609 km2 (21 July [Day 0.5507])
Down 8,080,946 km2 (60.88%) from 2015 maximum of 13,274,555 km2 on 17 February [Day 0.1288].
2,959,600 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Down 115,637 km2 from previous day.
Down 744,071 km2 over past seven days (daily average: -106,296 km2).
Down 2,261,212 km2 for the month of July (daily average: -107,677 km2).
713,438 km2 below 2000s average for this date.
52,892 km2 above 2010s average for this date.
256,384 km2 below 2014 value for this date.
535,762 km2 above 2012 value for this date.
5th lowest July to-date average.
4th lowest value for the date.
7 days this year (3.47% year-to-date) have recorded the lowest daily area.
19 days (9.41%) have recorded the second lowest.
29 days (14.36%) have recorded the third lowest.
55 days in total (27.23%) have been among the lowest three on record.
Title: Re: 2015 sea ice area and extent data
Post by: Vergent on July 21, 2015, 04:02:27 PM

NSIDC Daily Extent:

2015,    07,  14,      8.746,
2015,    07,  15,      8.615,   -131k   
2015,    07,  16,      8.403,   -212k
2015,    07,  17,      8.271,   -132k
2015,    07,  18,      8.120,   -151k
2015,    07,  19,      7.932,   -188k
2015,    07,  20,      7.903,   - 29k

6 day loss: 843K, averaging -140/day.

For reference 2012:

2012,    07,  14,      7.868..............2015,    07,  14,      8.746, ...................+878k   
2012,    07,  15,      7.705,  -163k....2015,    07,  15,      8.615,   -131k
2012,    07,  16,      7.606,   -99k.....2015,    07,  16,      8.403,   -212k
2012,    07,  17,      7.481,  -125k....2015,    07,  17,      8.271,   -132k
2012,    07,  18,      7.420,   -61k.....2015,    07,  18,      8.120,   -151k
2012,    07,  19,      7.350,   -70k.....2015,    07,  19,      7.932,   -188k..........+582k
2012,    07,  20,      7.340,   -10k.....2015,    07,  20,      7.903,   - 29k...........+563k
2012,    07,  21,      7.297,  -113k
2012,    07,  22,      7.184,  -113k
2012,    07,  23,      7.118,   -66k
2012,    07,  24,      7.035,   -83k
2012,    07,  25,      6.931,  -104k
2012,    07,  26,      6.809,  -122k
2012,    07,  27,      6.677,  -132k
2012,    07,  28,      6.600,   -77k
2012,    07,  29,      6.478,  -122k
2012,    07,  30,      6.400,   -78k
2012,    07,  31,      6.368,   -32k

Verg

Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on July 21, 2015, 04:15:40 PM
From today's NSIDC data update I calculate the following CT updates (the days in this list are the days of data released, three days behind ice dates):

Sun       5.491770
Mon -93.7  5.398043
Tue -88.8  5.309246
Wed -115.6  5.193628
Thu -47.1  5.146514

The lower decline on Thursday has the support of ESS (-20k8), CAB (-18k7). Laptev (-11k7) and CAA (-10k8).
Hudson that showed some huge declines in the last few days slightly rebounded (+8k7), even more by extent (calculated as NSIDC calculates it) of +20k4.

In the attached NSIDC delta map, pixels with larger concentration changes than 7% or colored pinkish (down) or light blue (up). Solid red and blue are where the pixel concentration crosses the 15% limit (for extent).
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on July 22, 2015, 12:47:35 PM
CT replaced the image with the date "2015-07-18" (not sure about the corresponding ice date) with a serious defect, quickly by another with corrected ice concentrations.
Title: Re: 2015 sea ice area and extent data
Post by: Vergent on July 22, 2015, 04:06:16 PM
NSIDC Daily Extent:



2012,    07,  14,      7.868..............2015,    07,  14,      8.746, ...................+878k   
2012,    07,  15,      7.705,  -163k....2015,    07,  15,      8.615,   -131k
2012,    07,  16,      7.606,   -99k.....2015,    07,  16,      8.403,   -212k
2012,    07,  17,      7.481,  -125k....2015,    07,  17,      8.271,   -132k
2012,    07,  18,      7.420,   -61k.....2015,    07,  18,      8.120,   -151k
2012,    07,  19,      7.350,   -70k.....2015,    07,  19,      7.932,   -188k..........+582k
2012,    07,  20,      7.340,   -10k.....2015,    07,  20,      7.903,   - 29k...........+563k
2012,    07,  21,      7.297,  -113k....2015,    07,  21,      7.807,   - 96k...........+580k
2012,    07,  22,      7.184,  -113k
2012,    07,  23,      7.118,   -66k
2012,    07,  24,      7.035,   -83k
2012,    07,  25,      6.931,  -104k
2012,    07,  26,      6.809,  -122k
2012,    07,  27,      6.677,  -132k
2012,    07,  28,      6.600,   -77k
2012,    07,  29,      6.478,  -122k
2012,    07,  30,      6.400,   -78k
2012,    07,  31,      6.368,   -32k

Verg
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on July 22, 2015, 04:15:48 PM
From today's NSIDC data update I calculate the following CT updates (the days in this list are the days of data released, three days behind ice dates):

Sun       5.491770
Mon -93.7  5.398043
Tue -88.8  5.309246
Wed -115.6  5.193628
Thu -46.9  5.146720
Fri -73.6  5.073109

Friday's -73.6 has been offset by a +20k6 bump in "lake ice". It did not affect NSIDC extent as they do not include lake ice. The regions that showed most of the area decline are ESS (-26k4), CAB (-16k1), Kara (-10k9) and Beaufort (-10k2). Of those Beaufort saw an increase in extent (calculated as NSIDC calculates extent) of +11k3.

In the attached NSIDC delta map, pixels with larger concentration changes than 7% or colored pinkish (down) or light blue (up). Solid red and blue are where the pixel concentration crosses the 15% limit (for extent).
Title: Re: 2015 sea ice area and extent data
Post by: greatdying2 on July 22, 2015, 04:37:43 PM
The regions that showed most of the area decline are ESS (-26k4), CAB (-16k1), Kara (-10k9) and Beaufort (-10k2). Of those Beaufort saw an increase in extent (calculated as NSIDC calculates extent) of +11k3.
So Beaufort is spreading out even more and the ice edge is being pushed outwards, towards the warm Mackenzie river outflow.
Title: Re: 2015 sea ice area and extent data
Post by: seaicesailor on July 22, 2015, 04:52:07 PM
The regions that showed most of the area decline are ESS (-26k4), CAB (-16k1), Kara (-10k9) and Beaufort (-10k2). Of those Beaufort saw an increase in extent (calculated as NSIDC calculates extent) of +11k3.
So Beaufort is spreading out even more and the ice edge is being pushed outwards, towards the warm Mackenzie river outflow.

I'd be not so sure about that, having been set clockwise rotation. We'll see next couple of days.

If low pressure system over Beaufort is confirmed later in a few days, what you say might happen.

Which does not mean the ice is going to melt right away.

No matter what, more MYI is slowly creeping in into the region from the CAA right now if the drift maps of the ASIG are to be trusted.
Title: Re: 2015 sea ice area and extent data
Post by: greatdying2 on July 22, 2015, 06:00:37 PM
Which does not mean the ice is going to melt right away.
Of course, but I guess the Mackenzie will be dumping heat into the ocean for many more weeks, well beyond the period when insolation has much impact.
Title: Re: 2015 sea ice area and extent data
Post by: seaicesailor on July 22, 2015, 06:48:49 PM
Which does not mean the ice is going to melt right away.
Of course, but I guess the Mackenzie will be dumping heat into the ocean for many more weeks, well beyond the period when insolation has much impact.

Much of the ice will eventually melt, but I'd have said "all the ice" a week ago. I am starting to lean to the side that maybe some Beaufort MYI might survive the season.

To follow up with the floe I talked about yesterday (first pic), a second pic from today's Uni Hamburg AMSR2 images (courtesy of Wipneus who generates these images). It is very close to the river delta, still its area evolves very slowly day after day, in waters supposed to be 4ºC plus (my estimate was 6ºC)

Title: Re: 2015 sea ice area and extent data
Post by: Tor Bejnar on July 22, 2015, 07:18:18 PM
If (some of) the large remaining floes in the Beaufort Sea are genuine old fashioned multiyear ice (MYI), they might be 5 or 10 m thick and not be honeycombed ("rotten") yet.  It will take a while for them to melt, even in 'warm' water.  Think Boston's pile of snow in June.
Title: Re: 2015 sea ice area and extent data
Post by: wanderer on July 22, 2015, 07:30:56 PM
We are still ex aequo with 2012:
https://sites.google.com/site/arctischepinguin/home/amsr2/grf/basin-extent-multiprod.png
https://sites.google.com/site/arctischepinguin/home/amsr2/grf/basin-area-multiprod.png

Title: Re: 2015 sea ice area and extent data
Post by: Neven on July 22, 2015, 07:41:25 PM

Much of the ice will eventually melt, but I'd have said "all the ice" a week ago. I am starting to lean to the side that maybe some Beaufort MYI might survive the season.

To follow up with the floe I talked about yesterday (first pic), a second pic from today's Uni Hamburg AMSR2 images (courtesy of Wipneus who generates these images). It is very close to the river delta, still its area evolves very slowly day after day, in waters supposed to be 4ºC plus (my estimate was 6ºC)

Remember the work Epiphyte did last year following a large floe in the Laptev Sea. When these large floes, they go suddenly.

Poof, it's gone (http://neven1.typepad.com/blog/2014/08/poof-its-gone.html)

Quote
The floe we are looking at here is a contiguous, high-albedo (snow-covered?) ~300km^2 chunk of ice at the edge of the pack. It remains so from 01-26 jul. On Jul 27, it becomes a little less bright and loses 10% of its area. Three days later - poof. It's gone.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fneven1.typepad.com%2F.a%2F6a0133f03a1e37970b01a73dfae4ec970d-800wi&hash=174e54fdd9c0f913700667f5153b3213)

Keep an eye on that ice floe, seaicesailor!
Title: Re: 2015 sea ice area and extent data
Post by: oren on July 22, 2015, 11:42:00 PM
Just by looking at the regional charts without any physics/weather, I expect Beaufort will not melt out this year, as melting thus far has been too slow. On the other hand the ESS seems well on its way to melting out completely. The CAA and the CAB haven't reached their big inflection points yet.
Title: Re: 2015 sea ice area and extent data
Post by: seaicesailor on July 23, 2015, 12:08:41 AM

Much of the ice will eventually melt, but I'd have said "all the ice" a week ago. I am starting to lean to the side that maybe some Beaufort MYI might survive the season.

To follow up with the floe I talked about yesterday (first pic), a second pic from today's Uni Hamburg AMSR2 images (courtesy of Wipneus who generates these images). It is very close to the river delta, still its area evolves very slowly day after day, in waters supposed to be 4ºC plus (my estimate was 6ºC)

Remember the work Epiphyte did last year following a large floe in the Laptev Sea. When these large floes, they go suddenly.

Poof, it's gone (http://neven1.typepad.com/blog/2014/08/poof-its-gone.html)

Quote
The floe we are looking at here is a contiguous, high-albedo (snow-covered?) ~300km^2 chunk of ice at the edge of the pack. It remains so from 01-26 jul. On Jul 27, it becomes a little less bright and loses 10% of its area. Three days later - poof. It's gone.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fneven1.typepad.com%2F.a%2F6a0133f03a1e37970b01a73dfae4ec970d-800wi&hash=174e54fdd9c0f913700667f5153b3213)

Keep an eye on that ice floe, seaicesailor!

Nice! Thank you Neven and Epiphyte for that study. The more interesting to follow this.
Title: Re: 2015 sea ice area and extent data
Post by: Michael Hauber on July 23, 2015, 01:14:13 AM
IJIS extent stats show that in the last week2012's lead has been cut in half (600k to 310k), and that 2014 has now been overtaken.  Both Hudson and East Siberian (ESS) have been in freefall, and Hudson is nearly at bottom, so is about to stop.  Although there is not a lot of ice left in the ESS the melt can keep going into the central Arctic.  Although the high pressure system is moving towards the Siberian side of the Arctic, overall temperatures look to remain quite high.  I have noticed that although the charts show high pressure and heat the Arctic has been cloudy of late and hard to get a good view.  Fog or low level cloud from the extra sea water vapor perhaps?  There seems to be a lot of similarity between this year in 2007 with the very strong melt in the ESS, and it looks a good chance now that 2015 will join 2007 and 2012 as the only other previous years in which the tongue of ice towards and into ESS that usually remains at minimum is completely wiped out.

In common with 2012 we currently have a large area of sea ice that has been dispersed and is mixed with significant amounts of open water.  In both years the dispersal coincided with a low pressure system around 20 June, and it is my belief that this dispersal makes the ice more vulnerable to solar radiation being absorbed by the water in between the floes.   The dispersed ice in 2012 had a larger area, with a lot of the ice in the Laptev sector also being dispersed in 2012, but looking reasonably solid (in 2 dimensions) on MODIS in 2015.  There did not seem to be any significant dispersal in 2007. 

To challenge 2012 I think we will need to see strong melt in the Laptev region as well.  Winter patterns seemed to lead to very thin ice in this sector, but so far I'd say the conditions seem to have been average, and regional extent and area figures are trailing a little.  The forecast movement of the high towards the Siberian side might give a better MODIS view of this sector which has been mostly covered by clouds, and perhaps some extra sunshine will help the melt along.

I do get the impression of two Arctics - the Pacific side which is very dispersed and will continue to melt rapidly, and the central and Atlantic side which shows minimal dispersion, and may not melt as fast.  As a guess I think we may see continued fast melt through to mid August, but once much of the Pacific side ice is gone melt will slow down for an average finish to the melt season, and a final result somewhere near 2007.  I'll be looking at MODIS images in coming weeks for evidence of weakening that may support continued strong melt beyond the currently dispersed area.

edit:  oops, I thought I was posting in the current melt season thread....
Title: Re: 2015 sea ice area and extent data
Post by: Neven on July 23, 2015, 01:30:10 AM
Post it there too, MH. :-)

Nice! Thank you Neven and Epiphyte for that study. The more interesting to follow this.

Maybe we should continue this Beaufort floe discussion over in the Melting season thread as well from now on. It's interesting, like you say. On the one hand it's MYI in the Beaufort, on the other hand, it's only July 23rd. I'll also try to keep an eye on it, if clouds permit.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on July 23, 2015, 04:11:06 PM
From today's NSIDC data update I calculate the following CT updates (the days in this list are the days of data released, three days behind ice dates):

Sun       5.491770
Mon -93.7  5.398043
Tue -88.8  5.309246
Wed -115.6  5.193628
Thu -46.9  5.146720
Fri -73.5  5.073213
Sat -43.5  5.029723

The slower decline on Saturday is mainly caused by an uptick in the CAB (+34k5). Regions with significant declines are ESS (-22k8),  Kara (-16k5) and Baffin (-10k5).

In the attached NSIDC delta map, pixels with larger concentration changes than 7% or colored pinkish (down) or light blue (up). Solid red and blue are where the pixel concentration crosses the 15% limit (for extent).
Title: Re: 2015 sea ice area and extent data
Post by: Neven on July 23, 2015, 04:32:09 PM
Very interesting. CT SIA decrease is showing signs of levelling off, even though weather conditions are remaining basically unchanged (perhaps slightly less heat), which is also causing CAPIE to level off.
Title: Re: 2015 sea ice area and extent data
Post by: Vergent on July 23, 2015, 04:34:58 PM
NSIDC Daily Extent:

2012 was a leap year, now comparing same Julian days.

2012,    07,  14,      7.868..............2015,     07,  15,      8.615,   -131k.....+747k
2012,    07,  15,      7.705,  -163k....2015,     07,  16,      8.403,   -212k
2012,    07,  16,      7.606,   -99k.....2015,     07,  17,      8.271,   -132k
2012,    07,  17,      7.481,  -125k....2015,     07,  18,      8.120,   -151k
2012,    07,  18,      7.420,   -61k.....2015,     07,  19,      7.932,   -188k
2012,    07,  19,      7.350,   -70k.....2015,     07,  20,      7.903,   - 29k
2012,    07,  20,      7.340,   -10k.....2015,     07,  21,      7.807,   - 96k
2012,    07,  21,      7.297,  -113k....2015,     07,  22,      7.658,   -149k.....+361
2012,    07,  22,      7.184,  -113k....
2012,    07,  23,      7.118,   -66k
2012,    07,  24,      7.035,   -83k
2012,    07,  25,      6.931,  -104k
2012,    07,  26,      6.809,  -122k
2012,    07,  27,      6.677,  -132k
2012,    07,  28,      6.600,   -77k
2012,    07,  29,      6.478,  -122k
2012,    07,  30,      6.400,   -78k
2012,    07,  31,      6.368,   -32k

Verg
Title: Re: 2015 sea ice area and extent data
Post by: BornFromTheVoid on July 23, 2015, 05:04:49 PM
We're already approaching some of the older September minimum values. Just 339k off the 1980 minimum.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2F60UThnL.png&hash=3d4825a39f4265474f929d070fea58aa)
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on July 23, 2015, 07:22:05 PM
We're already approaching some of the older September minimum values. Just 339k off the 1980 minimum.

Where CT SIA is concerned--and using Wipneus' numbers--2015 has already dropped below the annual minimums recorded in 1979, 1980, 1982, 1983, 1986, 1987, 1988, and 1996.
Title: Re: 2015 sea ice area and extent data
Post by: OldLeatherneck on July 23, 2015, 10:06:19 PM
In regards to ADS-NIPR (formerly IJIS) Sea Ice Extent, the last 7 days have seen a loss of slightly over 908K Km2.  It will be interesting to watch if 2015 will continue have above average losses through the middle of August.  Personally, I can not see any path for 2015 to eclipse 2012.  As for 2011 & 2007, they are vulnerable but not yet seriously threatened.  Will update and post my graphs and projections sometime over the weekend.
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on July 24, 2015, 01:41:14 PM
ADS-NIPR Extent:
7,201,855 km2 (23 July)
Down 6,740,205 km2 (48.34%) from 2015 maximum of 13,942,060 km2 on 15 February.
4,024,400 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Down 100,037 km2 (-1.37%)from previous day.
Down 853,064 km2  (-10.59%) over past seven days (daily average: -121,866 km2).
Down 2,280,461 km2  (-24.05%) for July (daily average: -99,150 km2).
759,008 km2 below 2000s average for this date.
94,470 km2 above 2010s average for this date.
130,079 km2 below 2014 value for this date.
262,717 km2 above 2012 value for this date.
8th lowest July to-date average.
5th lowest value for the date.
64 days this year (31.37% year-to-date) have recorded the lowest daily extent.
32 days (15.69%) have recorded the second lowest.
32 days (15.69%) have recorded the third lowest.
128 days (62.75%) in total have been among the three lowest on record.


CT Area:
NOTE: due to infrequent updates of official CT sea ice area data, I'm using a combination of those official data and Wipneus' calculated area numbers. The official numbers will be inserted as they become available.
5,029,723 km2 (24 July [Day 0.559])
Down 8,244,832 km2 (62.11%) from 2015 maximum of 13,274,555 km2 on 17 February [Day 0.1288].
2,795,714 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Down 43,386 km2 (-0.86%) from previous day.
Down 585,919 km2 (-10.43%) over past seven days (daily average: -83,703 km2).
Down 2,425,098 km2 (-32.53%) for July (daily average: -101,046 km2).
601,598 km2 below 2000s average for this date.
146,046 km2 above 2010s average for this date.
197,054 km2 below 2014 value for this date.
580,316 km2 above 2012 value for this date.
5th lowest July to-date average.
5th lowest value for the date.
7 days this year (3.41% year-to-date) have recorded the lowest daily area.
19 days (9.27%) have recorded the second lowest.
29 days (14.15%) have recorded the third lowest.
55 days in total (26.83%) have been among the lowest three on record.

Title: Re: 2015 sea ice area and extent data
Post by: Vergent on July 24, 2015, 03:56:28 PM
NSIDC Daily Extent:

2012 was a leap year, now comparing same Julian days.

2012,    07,  14,      7.868..............2015,     07,  15,      8.615,   -131k.....+747k
2012,    07,  15,      7.705,  -163k....2015,     07,  16,      8.403,   -212k
2012,    07,  16,      7.606,   -99k.....2015,     07,  17,      8.271,   -132k
2012,    07,  17,      7.481,  -125k....2015,     07,  18,      8.120,   -151k
2012,    07,  18,      7.420,   -61k.....2015,     07,  19,      7.932,   -188k
2012,    07,  19,      7.350,   -70k.....2015,     07,  20,      7.903,   - 29k
2012,    07,  20,      7.340,   -10k.....2015,     07,  21,      7.807,   - 96k
2012,    07,  21,      7.297,  -113k....2015,     07,  22,      7.658,   -149k.....+361k
2012,    07,  22,      7.184,  -113k....2015,    07,   23,      7.548,   -110k.....+364k
2012,    07,  23,      7.118,   -66k
2012,    07,  24,      7.035,   -83k
2012,    07,  25,      6.931,  -104k
2012,    07,  26,      6.809,  -122k
2012,    07,  27,      6.677,  -132k
2012,    07,  28,      6.600,   -77k
2012,    07,  29,      6.478,  -122k
2012,    07,  30,      6.400,   -78k
2012,    07,  31,      6.368,   -32k

Verg
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on July 24, 2015, 04:13:49 PM
From today's NSIDC data update I calculate the following CT updates (the days in this list are the days of data released, three days behind ice dates):

Fri       5.072222
Sat -43.6  5.028612
Sun -87.0  4.941621

Sunday's decline (increased by "lake ice" -10k4) is supported by the CAB(-20k6), ESS (-20k3) and Kara (-14k9).

Beaufort drops in extent (-15k8 NSIDC calculation) yet the area increases a little (+7k5 CT calculation).

In the attached NSIDC delta map, pixels with larger concentration changes than 7% or colored pinkish (down) or light blue (up). Solid red and blue are where the pixel concentration crosses the 15% limit (for extent).
Title: Re: 2015 sea ice area and extent data
Post by: Vergent on July 25, 2015, 03:57:18 PM
NSIDC Daily Extent:

2012 was a leap year, now comparing same Julian days.

2012,    07,  14,      7.868..............2015,     07,  15,      8.615,   -131k.....+747k
2012,    07,  15,      7.705,  -163k....2015,     07,  16,      8.403,   -212k
2012,    07,  16,      7.606,   -99k.....2015,     07,  17,      8.271,   -132k
2012,    07,  17,      7.481,  -125k....2015,     07,  18,      8.120,   -151k
2012,    07,  18,      7.420,   -61k.....2015,     07,  19,      7.932,   -188k
2012,    07,  19,      7.350,   -70k.....2015,     07,  20,      7.903,   - 29k
2012,    07,  20,      7.340,   -10k.....2015,     07,  21,      7.807,   - 96k
2012,    07,  21,      7.297,  -113k....2015,     07,  22,      7.658,   -149k.....+361k
2012,    07,  22,      7.184,  -113k....2015,     07,   23,     7.548,   -110k.....+364k
2012,    07,  23,      7.118,   -66k.....2015,     07,  24,      7.434,   -114k.....+316k
2012,    07,  24,      7.035,   -83k
2012,    07,  25,      6.931,  -104k
2012,    07,  26,      6.809,  -122k
2012,    07,  27,      6.677,  -132k
2012,    07,  28,      6.600,   -77k
2012,    07,  29,      6.478,  -122k
2012,    07,  30,      6.400,   -78k
2012,    07,  31,      6.368,   -32k

Verg
Title: Re: 2015 sea ice area and extent data
Post by: Bob Wallace on July 25, 2015, 04:50:14 PM
In regards to ADS-NIPR (formerly IJIS) Sea Ice Extent, the last 7 days have seen a loss of slightly over 908K Km2.  It will be interesting to watch if 2015 will continue have above average losses through the middle of August.  Personally, I can not see any path for 2015 to eclipse 2012.  As for 2011 & 2007, they are vulnerable but not yet seriously threatened.  Will update and post my graphs and projections sometime over the weekend.

If you look at Wip's graph for the central basin 2015 extent is lower than 2012 at this time.  This doesn't say that 2015 will finish lower, but it does leave the possibility that weather similar to 2012 could take the melt to a new low.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi619.photobucket.com%2Falbums%2Ftt275%2FBob_Wall%2Fbasin-extent-multiprod%252020150725.png&hash=cd080cbf6f85fd98f9064fa2632cabee) (http://s619.photobucket.com/user/Bob_Wall/media/basin-extent-multiprod%2020150725.png.html)
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on July 25, 2015, 04:59:52 PM
From today's NSIDC data update I calculate the following CT updates (the days in this list are the days of data released, three days behind ice dates):

Fri         5.072222
Sat  -43.6  5.028612
Sun  -86.9  4.941706
Mon -183.3  4.758386

The large day-to-day changes seem to back. The big decline on Monday (which includes a -17k from "lake ice") is mainly brought by the CAB (-60k), CAA (-29k), Baffin (-25k). Smaller contributions (~-12k) by Laptev, ESS and Greenland Sea.

In the attached NSIDC delta map, pixels with larger concentration changes than 7% or colored pinkish (down) or light blue (up). Solid red and blue are where the pixel concentration crosses the 15% limit (for extent).
Title: Re: 2015 sea ice area and extent data
Post by: Neven on July 25, 2015, 05:09:46 PM
So much for signs of levelling off. With that 183K drop 2015 dips below 2013, in 4th position now. And depending on JAXA SIE, CAPIE will drop some more too.
Title: Re: 2015 sea ice area and extent data
Post by: Rubikscube on July 25, 2015, 05:41:12 PM
Days like this makes such a difference. 2014 is already firmly distanced and 2013 starts going uphill from here. The chance of 2015 finishing above those years has now reached statistically insignificant, as far as I can see, that goes for 2009 as well.
Title: Re: 2015 sea ice area and extent data
Post by: Neven on July 25, 2015, 05:44:41 PM
The chance of 2015 finishing above those years has now reached statistically insignificant, as far as I can see, that goes for 2009 as well.

Be careful, RC! Anything is possible in the Arctic, but that goes both ways, of course.
Title: Re: 2015 sea ice area and extent data
Post by: seaicesailor on July 25, 2015, 06:20:15 PM
Yes, just as regions with little relevance have been giving the last they had very fast (Baffin and Hudson), regions with a lot of potential to turn the balance in either direction are being slow (Chukchi and Beaufort).

ESS is a rocket, just opposite to previous years.
Laptev finally going down fast.

Chukchi front (which is entering the CAB, or so), is especially slow compared to 10 days ago.

Edit: talking about extent.
Title: Re: 2015 sea ice area and extent data
Post by: epiphyte on July 25, 2015, 07:08:22 PM
So much for signs of levelling off. With that 183K drop 2015 dips below 2013, in 4th position now. And depending on JAXA SIE, CAPIE will drop some more too.

Poof.
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on July 25, 2015, 09:38:35 PM
So much for signs of levelling off. With that 183K drop 2015 dips below 2013, in 4th position now. And depending on JAXA SIE, CAPIE will drop some more too.

Yes. And with that drop, 2015 has dropped below the area minimums recorded in 1979-1983, 1985-1989, 1992, 1994, 1996, and 1997.

That 183k drop is the third largest post-25 July single-day decrease recorded in the previous ten years. (How's that for obscure?)
Title: Re: 2015 sea ice area and extent data
Post by: Tor Bejnar on July 25, 2015, 10:52:09 PM
Quote
(How's that for obscure?)
Sounds like you are attempting to get us to fact check your statement. :D
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on July 26, 2015, 02:12:51 PM
ADS-NIPR Extent:
7,001,792 km2 (25 July)
Down 6,940,268 km2 (49.78%) from 2015 maximum of 13,942,060 km2 on 15 February.
3,824,337 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Down 115,285 km2 (-1.62%) from previous day.
Down 765,209 km2  (-9.85%) over past seven days (daily average: -109,316 km2).
Down 2,480,524 km2  (-26.16%) for July (daily average: -99,221 km2).
796,865 km2 below 2000s average for this date.
55,300 km2 above 2010s average for this date.
252,433 km2 below 2014 value for this date.
384,485 km2 above 2012 value for this date.
7th lowest July to-date average.
5th lowest value for the date.
64 days this year (31.07% year-to-date) have recorded the lowest daily extent.
32 days (15.53%) have recorded the second lowest.
32 days (15.53%) have recorded the third lowest.
128 days (62.14%) in total have been among the three lowest on record.


CT Area:
NOTE: due to infrequent updates of official CT sea ice area data, I'm using a combination of those official data and Wipneus' calculated area numbers. The official numbers will be inserted as they become available.
4,758,386 km2 (26 July [Day 0.5643])
Down 8,516,169 km2 (64.15%) from 2015 maximum of 13,274,555 km2 on 17 February [Day 0.1288].
2,524,377 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Down 183,235 km2 (-3.71%) from previous day.
Down 640,224 km2 (-11.86%) over past seven days (daily average: -91,461 km2).
Down 2,696,435 km2 (-36.17%) for July (daily average: -103,709 km2).
737,843 km2 below 2000s average for this date.
26,718 km2 above 2010s average for this date.
345,099 km2 below 2014 value for this date.
417,014 km2 above 2012 value for this date.
5th lowest July to-date average.
4th lowest value for the date.
7 days this year (3.38% year-to-date) have recorded the lowest daily area.
19 days (9.18%) have recorded the second lowest.
29 days (14.01%) have recorded the third lowest.
55 days in total (26.57%) have been among the lowest three on record.
Title: Re: 2015 sea ice area and extent data
Post by: Neven on July 26, 2015, 02:24:09 PM
And as expected, CAPIE dips, despite a century break from IJIS (I'll start calling them differently next year):
Title: Re: 2015 sea ice area and extent data
Post by: OldLeatherneck on July 26, 2015, 02:41:05 PM
The last 10 days has seen a loss of slightly more than 1.2M Km2 of SIE according to ADR-NIPR.  I think it's safe to say that the rebound is finally over.  With the current forecasts and the general state of the ice, 2015 will most probably finish the season between 3rd and 5th lowest on record.  With well above average losses in August, there's even a possibility of eclipsing 2007.  The reason 2012 is so difficult to beat is that it lost almost 2.6M Km2 in August.

Below are my updated charts and a table of projected loss scenarios, based on the average losses of years 2003-2014.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi1269.photobucket.com%2Falbums%2Fjj597%2FOldLeatherNeck%2FADR-NIPR%2520Arctic%2520sea%2520ice%2520extent%252025%2520July%25202015%2520Power%2520point_zps2ch2f9gr.jpg&hash=f611cab84f43aa8f094aa0ccb5f3e33b)

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi1269.photobucket.com%2Falbums%2Fjj597%2FOldLeatherNeck%2FADS-NIPR%2520Arctic%2520sea%2520ice%2520projections%252025%2520July%25202015_zps7kgiyuyo.jpg&hash=19a073cae702fcf4421acee05aa1693c)
Title: Re: 2015 sea ice area and extent data
Post by: Vergent on July 26, 2015, 03:54:01 PM
NSIDC Daily Extent:

2012 was a leap year, now comparing same Julian days.

2012,    07,  14,      7.868..............2015,     07,  15,      8.615,   -131k.....+747k
2012,    07,  15,      7.705,  -163k....2015,     07,  16,      8.403,   -212k
2012,    07,  16,      7.606,   -99k.....2015,     07,  17,      8.271,   -132k
2012,    07,  17,      7.481,  -125k....2015,     07,  18,      8.120,   -151k
2012,    07,  18,      7.420,   -61k.....2015,     07,  19,      7.932,   -188k
2012,    07,  19,      7.350,   -70k.....2015,     07,  20,      7.903,   - 29k
2012,    07,  20,      7.340,   -10k.....2015,     07,  21,      7.807,   - 96k
2012,    07,  21,      7.297,  -113k....2015,     07,  22,      7.658,   -149k.....+361k
2012,    07,  22,      7.184,  -113k....2015,     07,   23,     7.548,   -110k.....+364k
2012,    07,  23,      7.118,   -66k.....2015,     07,  24,      7.434,   -114k.....+316k
2012,    07,  24,      7.035,   -83k.....2015,     07,  25,      7.320,   -114k.....+285k
2012,    07,  25,      6.931,  -104k
2012,    07,  26,      6.809,  -122k
2012,    07,  27,      6.677,  -132k
2012,    07,  28,      6.600,   -77k
2012,    07,  29,      6.478,  -122k
2012,    07,  30,      6.400,   -78k
2012,    07,  31,      6.368,   -32k

Verg
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on July 26, 2015, 04:07:35 PM
From today's NSIDC data update I calculate the following CT updates (the days in this list are the days of data released, three days behind ice dates):

Fri       5.072222
Sat -43.6  5.028612
Sun -86.9  4.941706
Mon -183.1  4.758563
Tue -85.0  4.673542

Support mostly by CAB (-46k), then nothing and then Laptev and Hudson ( both -13k).

In the attached NSIDC delta map, pixels with larger concentration changes than 7% or colored pinkish (down) or light blue (up). Solid red and blue are where the pixel concentration crosses the 15% limit (for extent).
Title: Re: 2015 sea ice area and extent data
Post by: BornFromTheVoid on July 26, 2015, 04:30:26 PM
Update for the week to July 25th

The current 5 day mean is on 7,553,400km2 while the 1 day extent is at 7,320,000km2.
The daily anomaly (compared to 81-10) is at -1,306,980km2, an increase from -1,052,840km2 last week. The anomaly compared to the 07, 11 and 12 average is at +438,553km2, a decrease from +754,867km2 last week. We're currently 6th lowest on record, up from 7th last week.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FNcl4XZs.png&hash=6bbaaa4268275d926de1fb1219f20973)

The average daily change over the last 7 days was -125.5k/day, compared to the long term average of -89.0k/day, and the 07, 11 and 12 average of -80.2k/day.
The average long term change over the next week is -85.1k/day, with the 07, 11, and 12 average being -76.7k/day.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FDvFhApu.png&hash=4038028ddcda8a9008eaa14f13468887)

The loss so far this July is the 5th largest on record. To achieve the largest monthly drop, a daily loss of at least 148.1k/day is required, while the smallest drop requires an increase of at least 102.9k/day and an average drop requires a loss of 6.4k/day.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FX00MAp1.png&hash=69d22d40d5585ccc046a72a89c9ff0f6)
Title: Re: 2015 sea ice area and extent data
Post by: Shared Humanity on July 26, 2015, 11:44:25 PM
Stands a good chance of finishing 4th.
Title: Re: 2015 sea ice area and extent data
Post by: DavidR on July 27, 2015, 04:07:19 PM
A 15k uptick on NSIDC extent today. I  suspect its just  windy.   I  can't wait to see what the area does.
Title: Re: 2015 sea ice area and extent data
Post by: Vergent on July 27, 2015, 04:10:07 PM
NSIDC Daily Extent:

2012 was a leap year, now comparing same Julian days.

2012,    07,  14,      7.868..............2015,     07,  15,      8.615,   -131k.....+747k
2012,    07,  15,      7.705,  -163k....2015,     07,  16,      8.403,   -212k
2012,    07,  16,      7.606,   -99k.....2015,     07,  17,      8.271,   -132k
2012,    07,  17,      7.481,  -125k....2015,     07,  18,      8.120,   -151k
2012,    07,  18,      7.420,   -61k.....2015,     07,  19,      7.932,   -188k
2012,    07,  19,      7.350,   -70k.....2015,     07,  20,      7.903,   - 29k
2012,    07,  20,      7.340,   -10k.....2015,     07,  21,      7.807,   - 96k
2012,    07,  21,      7.297,  -113k....2015,     07,  22,      7.658,   -149k.....+361k
2012,    07,  22,      7.184,  -113k....2015,     07,   23,     7.548,   -110k.....+364k
2012,    07,  23,      7.118,   -66k.....2015,     07,  24,      7.434,   -114k.....+316k
2012,    07,  24,      7.035,   -83k.....2015,     07,  25,      7.320,   -114k.....+285k
2012,    07,  25,      6.931,  -104k....2015,     07,  26,      7.335,   + 15.......+404
2012,    07,  26,      6.809,  -122k
2012,    07,  27,      6.677,  -132k
2012,    07,  28,      6.600,   -77k
2012,    07,  29,      6.478,  -122k
2012,    07,  30,      6.400,   -78k
2012,    07,  31,      6.368,   -32k

Verg
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on July 27, 2015, 05:32:25 PM
From today's NSIDC data update I calculate the following CT updates (the days in this list are the days of data released, three days behind ice dates):

Sun       4.942303
Mon -183.1  4.759160
Tue -85.0  4.674158
Wed -54.4  4.619771

The Wednesday's decline was mainly caused by a -30k5 decline in the CAB, with a -12k3 hand from Kara. Only small ++ and -- in other regions.

Curiously extent increased (calculated by the NSIDC method) by the same regions: CAB (+2k6) and Kara (+21k3). Here Hudson and Laptev need to be mentioned, canceling each other with a +14k4  and -14k1 respectively.

In the attached NSIDC delta map, pixels with larger concentration changes than 7% or colored pinkish (down) or light blue (up). Solid red and blue are where the pixel concentration crosses the 15% limit (for extent).
Title: Re: 2015 sea ice area and extent data
Post by: jdallen on July 27, 2015, 05:37:51 PM
A 15k uptick on NSIDC extent today. I  suspect its just  windy.   I  can't wait to see what the area does.
Indeed, absolutely some dispersion; a grab from earth.nullschool.net surface winds suggests it.

Area probably is still dropping much as it has been - 80-120K KM2/day.
Title: Re: 2015 sea ice area and extent data
Post by: BornFromTheVoid on July 27, 2015, 07:15:05 PM
The 5 day mean NSIDC extent has just dipped below the 1980 September minimum and is within 500k of 7 other minima.

Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on July 27, 2015, 09:37:45 PM
The 5 day mean NSIDC extent has just dipped below the 1980 September minimum and is within 500k of 7 other minima.

...And while we're at it: according to Wipneus' calculations, CT SIA has dropped below the minima recorded from 1980-1990, plus those recorded in 1992, 1994, 1996, and 1997. Next three on deck: 2001, 1993, and 1991, all of which should be overtaken sometime in the next four or five days.
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on July 28, 2015, 01:04:40 PM
ADS-NIPR Extent:
6,843,550 km2 (27 July)
Down 7,098,510 km2 (50.91%) from 2015 maximum of 13,942,060 km2 on 15 February.
3,666,095 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Down 75,329 km2 (-1.09%) from previous day.
Down 678,958 km2  (-9.03%) over past seven days (daily average: -96,994 km2).
Down 2,638,766 km2  (-27.83%) for July (daily average: -97,732 km2).
793,791 km2 below 2000s average for this date.
58,948 km2 above 2010s average for this date.
254,357 km2 below 2014 value for this date.
477,432 km2 above 2012 value for this date.
7th lowest July to-date average.
4th lowest value for the date.
64 days this year (30.77% year-to-date) have recorded the lowest daily extent.
32 days (15.38%) have recorded the second lowest.
32 days (15.38%) have recorded the third lowest.
128 days (61.54%) in total have been among the three lowest on record.


CT Area:
NOTE: due to infrequent updates of official CT sea ice area data, I'm using a combination of those official data and Wipneus' calculated area numbers. The official numbers will be inserted as they become available.
4,619,771 km2 (28 July [Day 0.5698])
Down 8,654,784 km2 (65.2%) from 2015 maximum of 13,274,555 km2 on 17 February [Day 0.1288].
2,385,762 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Down 53,771 km2 (-1.15%) from previous day.
Down 573,269 km2 (-11.04%) over past seven days (daily average: -81,896 km2).
Down 2,835,050 km2 (-38.03%) for July (daily average: -101,252 km2).
785,102 km2 below 2000s average for this date.
66,436 km2 below 2010s average for this date.
513,022 km2 below 2014 value for this date.
320,666 km2 above 2012 value for this date.
5th lowest July to-date average.
4th lowest value for the date.
7 days this year (3.35% year-to-date) have recorded the lowest daily area.
19 days (9.09%) have recorded the second lowest.
29 days (13.88%) have recorded the third lowest.
55 days in total (26.32%) have been among the lowest three on record.
Title: Re: 2015 sea ice area and extent data
Post by: Vergent on July 28, 2015, 03:53:05 PM
NSIDC Daily Extent:

2012 was a leap year, now comparing same Julian days.

2012,    07,  14,      7.868..............2015,     07,  15,      8.615,   -131k.....+747k
2012,    07,  15,      7.705,  -163k....2015,     07,  16,      8.403,   -212k
2012,    07,  16,      7.606,   -99k.....2015,     07,  17,      8.271,   -132k
2012,    07,  17,      7.481,  -125k....2015,     07,  18,      8.120,   -151k
2012,    07,  18,      7.420,   -61k.....2015,     07,  19,      7.932,   -188k
2012,    07,  19,      7.350,   -70k.....2015,     07,  20,      7.903,   - 29k
2012,    07,  20,      7.340,   -10k.....2015,     07,  21,      7.807,   - 96k
2012,    07,  21,      7.297,  -113k....2015,     07,  22,      7.658,   -149k.....+361k
2012,    07,  22,      7.184,  -113k....2015,     07,   23,     7.548,   -110k.....+364k
2012,    07,  23,      7.118,   -66k.....2015,     07,  24,      7.434,   -114k.....+316k
2012,    07,  24,      7.035,   -83k.....2015,     07,  25,      7.320,   -114k.....+285k
2012,    07,  25,      6.931,  -104k....2015,     07,  26,      7.335,   + 15.......+404k
2012,    07,  26,      6.809,  -122k....2015,     07,  27,      7.236,    - 99.......+427k
2012,    07,  27,      6.677,  -132k
2012,    07,  28,      6.600,   -77k
2012,    07,  29,      6.478,  -122k
2012,    07,  30,      6.400,   -78k
2012,    07,  31,      6.368,   -32k

Verg
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on July 28, 2015, 04:12:31 PM
From today's NSIDC data update I calculate the following CT updates (the days in this list are the days of data released, three days behind ice dates):

Tue       4.674303
Wed -54.4  4.619916
Thu -57.1  4.562800

Thursday's half century was brought to you by the CAB (-16k), Hudson (-14k) and Baffin (-11k).

In the attached NSIDC delta map, pixels with larger concentration changes than 7% or colored pinkish (down) or light blue (up). Solid red and blue are where the pixel concentration crosses the 15% limit (for extent).
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on July 29, 2015, 04:23:08 PM
From today's NSIDC data update I calculate the following CT updates (the days in this list are the days of data released, three days behind ice dates):

Tue       4.674303
Wed -54.4  4.619916
Thu -57.2  4.562677
Fri -30.0  4.532652

Frisday's 30k includes a -18k2 by the Hudson, offset by a +12k7 from Baffin and lots of little contributions (5-8k) from other regions.

In the attached NSIDC delta map, pixels with larger concentration changes than 7% or colored pinkish (down) or light blue (up). Solid red and blue are where the pixel concentration crosses the 15% limit (for extent).
Title: Re: 2015 sea ice area and extent data
Post by: Sourabh on July 29, 2015, 04:35:03 PM
Wipneus,

Is it a temporary slowdown or does it look similar to what 2013 and 2014 experienced around the same time ?
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on July 29, 2015, 05:51:24 PM
Wipneus,

Is it a temporary slowdown or does it look similar to what 2013 and 2014 experienced around the same time ?

Sorry that I cannot tell you what is going to happen. Some increase again is quite likely (that uptick in the Baffin will surely come back), but as you say a slow down is normal.
On the other hand we have seen it before when that did not happen and instead of a slowdown it went up! Now how likely (or even possible ) is that?

In the 2012 animation the blue's are area in melting, deeper blue mean more melting by area.

Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on July 29, 2015, 09:50:54 PM
Wipneus,

Is it a temporary slowdown or does it look similar to what 2013 and 2014 experienced around the same time ?

That's a huge question. Day 0.5753--30 July-- was the last day 2014's late-July plateau; SIA dropped 54k over the following five days before entering a two-week period with a total decrease of just 114k (followed by an eight-day loss of 587k).  For 2013, Day 0.5753 marked the halfway spot of the eight-day 82k increase, which was followed by a ten-day loss of 683k. And, of course, on Day 0.5781, 2012 began a remarkable GAC-aided 12-day period that saw a loss of 1.14 million.
Title: Re: 2015 sea ice area and extent data
Post by: Vergent on July 30, 2015, 02:47:12 AM
Jim,
not happening this year....
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FabFgYoD.png&hash=bfff4a20993bb26561c24ae6991301f3)
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FCJhCwQe.png&hash=2dbfed3168e9e1a4ffef2ecf9ce41c56)

Verg
Title: Re: 2015 sea ice area and extent data
Post by: slow wing on July 30, 2015, 08:36:26 AM
Those two graphs are comparing apples to oranges, or - to be more accurate - browns to oranges.

The colour scale is completely different between the two plots.
Title: Re: 2015 sea ice area and extent data
Post by: Neven on July 30, 2015, 08:39:05 AM
Here are just apples, from the latest ASI update on the blog:

Quote
Things continue to heat up everywhere, although I expected much more heat on the Pacific side of the Arctic, given the situation two weeks ago when SST anomaly was off the scale in that part of the Arctic. Still, it's comparable to the situation on July 28th 2012, August 4th 2014 (ie one week from now), and much, much warmer than July 26th 2014:

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fneven1.typepad.com%2F.a%2F6a0133f03a1e37970b01b8d1405fba970c-800wi&hash=69d90f32c0c8ab64595c1d25233c459d)

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fneven1.typepad.com%2F.a%2F6a0133f03a1e37970b01b7c7b6dfc7970b-800wi&hash=911f0c6279b51061984fa04e89d3a636)
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on July 30, 2015, 12:57:06 PM
ADS-NIPR Extent:
6,730,052 km2 (29 July)
Down 7,212,008 km2 (51.73%) from 2015 maximum of 13,942,060 km2 on 15 February.
3,552,597 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Down 63,818 km2 (-.94%) from previous day.
Down 571,840 km2  (-7.83%) over past seven days (daily average: -81,691 km2).
Down 2,752,264 km2  (-29.03%) for July (daily average: -94,906 km2).
740,857 km2 below 2000s average for this date.
83,866 km2 above 2010s average for this date.
163,436 km2 below 2014 value for this date.
527,019 km2 above 2012 value for this date.
7th lowest July to-date average.
5th lowest value for the date.
64 days this year (30.48% year-to-date) have recorded the lowest daily extent.
32 days (15.24%) have recorded the second lowest.
32 days (15.24%) have recorded the third lowest.
128 days (60.95%) in total have been among the three lowest on record.


CT Area:
NOTE: due to infrequent updates of official CT sea ice area data, I'm using a combination of those official data and Wipneus' calculated area numbers. The official numbers will be inserted as they become available.
4,532,652 km2 (30 July [Day 0.5753])
Down 8,741,903 km2 (65.85%) from 2015 maximum of 13,274,555 km2 on 17 February [Day 0.1288].
2,298,643 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Down 30,148 km2 (-.66%) from previous day.
Down 539,570 km2 (-10.64%) over past seven days (daily average: -77,081 km2).
Down 2,922,169 km2 (-39.2%) for July (daily average: -97,406 km2).
754,312 km2 below 2000s average for this date.
66,915 km2 below 2010s average for this date.
655,532 km2 below 2014 value for this date.
296,785 km2 above 2012 value for this date.
5th lowest July to-date average.
5th lowest value for the date.
7 days this year (3.32% year-to-date) have recorded the lowest daily area.
19 days (9.%) have recorded the second lowest.
29 days (13.74%) have recorded the third lowest.
55 days in total (26.07%) have been among the lowest three on record.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on July 30, 2015, 04:33:01 PM
From today's NSIDC data update I calculate the following CT updates (the days in this list are the days of data released, three days behind ice dates):

Thu       4.562689
Fri -30.1  4.532572
Sat -119.4  4.413175

Saturday's century is mostly the result of the CAB (-63k4). Smaller contributions from Baffin(-17k), CAA (-15k) and Laptev (-14k).

Some of the concentration drop seems to align with the heating over the north of CAA and the bordering CAB.

In the attached NSIDC delta map, pixels with larger concentration changes than 7% or colored pinkish (down) or light blue (up). Solid red and blue are where the pixel concentration crosses the 15% limit (for extent).
Title: Re: 2015 sea ice area and extent data
Post by: Neven on July 30, 2015, 04:43:54 PM
If I'm not mistaken that's this year's 43rd century break, just as much as 2013 at this point, and one more than 2012. But 2012 saw 5 CBs in August, and 2013 only 2.

This century break will cause another drop on CAPIE.
Title: Re: 2015 sea ice area and extent data
Post by: plinius on July 30, 2015, 04:59:05 PM
Notably, area is now less than 200k above the 2012 value. Given that we are still offset by slightly more than that in Hudson and Baffin, I'd call that quite impressive  (though admittedly we are just before the big 2012 loss).

Also notable: We are now 20 days ahead of 2014, and 10 days ahead of 2013.
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on July 30, 2015, 06:16:14 PM
If I'm not mistaken that's this year's 43rd century break, just as much as 2013 at this point, and one more than 2012. But 2012 saw 5 CBs in August, and 2013 only 2.

This century break will cause another drop on CAPIE.

Using a slightly different metric: that's the 41st CB since this year's maximum, where 2012 had but 39 from its maximum through now. However--and this is probably somewhat telling--this year has had only two double century breaks since the maximum, while 2012 had counted seven by now.
Title: Re: 2015 sea ice area and extent data
Post by: slow wing on July 31, 2015, 04:17:55 AM
From today's NSIDC data update I calculate the following CT updates (the days in this list are the days of data released, three days behind ice dates):

Thu       4.562689
Fri -30.1  4.532572
Sat -119.4  4.413175

Wondering if Sunday is going to be a big loss as well? Maybe even bigger? That is from looking at the trend in U.Bremen concentration maps, ending with the map for 30 July (which will correspond to Sunday's update, if I am understanding correctly).
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on July 31, 2015, 07:57:29 AM

Wondering if Sunday is going to be a big loss as well? Maybe even bigger? That is from looking at the trend in U.Bremen concentration maps, ending with the map for 30 July (which will correspond to Sunday's update, if I am understanding correctly).

You understand correctly. Also in the latest updates of Uni Hamburg SIC, Jaxa SIC and ADS-NIPR AMSR2 thickness/melting , the slow down is nowhere to be found.
Title: Re: 2015 sea ice area and extent data
Post by: Neven on July 31, 2015, 09:46:31 AM

Wondering if Sunday is going to be a big loss as well? Maybe even bigger? That is from looking at the trend in U.Bremen concentration maps, ending with the map for 30 July (which will correspond to Sunday's update, if I am understanding correctly).

You understand correctly. Also in the latest updates of Uni Hamburg SIC, Jaxa SIC and ADS-NIPR AMSR2 thickness/melting , the slow down is nowhere to be found.

And compactness is still lowest too, everywhere except on CAPIE:

(https://sites.google.com/site/arctischepinguin/_/rsrc/1438321394303/home/amsr2/grf/amsr2-compact-compare.png)
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on July 31, 2015, 04:20:49 PM
From today's NSIDC data update I calculate the following CT updates (the days in this list are the days of data released, three days behind ice dates):

Thu       4.562689
Fri -30.1  4.532572
Sat -119.3  4.413302
Sun -127.4  4.285889

So no slowdown on Sunday. The hardest hit is for CAB (-56k8). Kara, ESS , Baffin and CAA all contribute around -11k.

Remaining ice area of Hudson and Baffin regions is 194k (about normal for the 1981-2010 period).

In the attached NSIDC delta map, pixels with larger concentration changes than 7% or colored pinkish (down) or light blue (up). Solid red and blue are where the pixel concentration crosses the 15% limit (for extent).
Title: Re: 2015 sea ice area and extent data
Post by: DavidR on July 31, 2015, 04:38:39 PM
According to my  figures that  puts SIA at  second lowest;  just  50K km^2 above 2012. and NSIDC compaction (SIA/SIE) at 4.3% below 2012.  (66.2% vs 61.9%).

That  suggests there is plenty of room for further rapid reductions.
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on July 31, 2015, 06:05:14 PM
According to my  figures that  puts SIA at  second lowest;  just  50K km^2 above 2012. and NSIDC compaction (SIA/SIE) at 4.3% below 2012.  (66.2% vs 61.9%).

That  suggests there is plenty of room for further rapid reductions.
Are you sure about that second place? Using Wipneus' numbers, my records show CT SIA as 4th place for Day 0.5835, 371k behind 2012:

2012: 3,915,334 km2
2011: 4,186,187 km2
2007: 4,270,627 km2
2015: 4,285,889 km2

OTOH, 2015 SIA is now a pretty comfortable 512k ahead of 2013, and a remarkable 728k km2 ahead of 2014. (So much for the "rebound").

My take: 2015 almost certainly won't catch 2012; at this point, that would require an further loss of greater thasn 2 million km2. But beating 2007 for second is a very real possibility at this point; to do so, we'd need to see another 1.37 million km2 of loss over the next six weeks or so, an average of roughly 35k per day. (For the record, 2007 lost 1.35 million km2 between now and that year's maximum; 2013 dropped by an additional 1.244 million; 2014 lost another 1.53 million; and 2012 squeezed out another 1.68 million.)

Title: Re: 2015 sea ice area and extent data
Post by: seaicesailor on July 31, 2015, 06:18:03 PM
NDSIC SIE fell 140+
Singular
With all the mess in the Pacific side
Title: Re: 2015 sea ice area and extent data
Post by: plinius on July 31, 2015, 06:34:40 PM
From today's NSIDC data update I calculate the following CT updates (the days in this list are the days of data released, three days behind ice dates):

Thu       4.562689
Fri -30.1  4.532572
Sat -119.3  4.413302
Sun -127.4  4.285889

So no slowdown on Sunday. The hardest hit is for CAB (-56k8). Kara, ESS , Baffin and CAA all contribute around -11k.

Remaining ice area of Hudson and Baffin regions is 194k (about normal for the 1981-2010 period).

In the attached NSIDC delta map, pixels with larger concentration changes than 7% or colored pinkish (down) or light blue (up). Solid red and blue are where the pixel concentration crosses the 15% limit (for extent).

aren't you one day off? Friday is day 210, and cryosphere shows 4.08 for day 212 in 2012, so the truth is between you two. Though of course I agree it is not probable that we catch 2012, given the very high losses 2012 showed over the next days.
Title: Re: 2015 sea ice area and extent data
Post by: dmarcus on July 31, 2015, 08:37:37 PM
"aren't you 1 day off?"

Is this a leap year issue? If you compare July 31, 2015 to July 31, 2012 you get one result. If you compare day 210 of 2015 to day 210 of 2012 you get a (slightly) different result. Is one better than the other, or are they just different? They each create a potential problem: If you compare dates, then it's hard to compare to February 29. If you compare days of the year, it's hard to compare to Day 366.
Title: Re: 2015 sea ice area and extent data
Post by: plinius on July 31, 2015, 08:52:25 PM
Could interpolate values onto true date in the solar year, if one wants to go for that. So, our day 210 in 2015 is in truth the day 210.75.
Title: Re: 2015 sea ice area and extent data
Post by: dmarcus on July 31, 2015, 08:57:30 PM
Or just choose one of the two straightforward methods, with an exclusionary rule: "No comparisons allowed on February 29, or on Day 366!"  ;)
Title: Re: 2015 sea ice area and extent data
Post by: Neven on July 31, 2015, 09:21:29 PM
Wow, amazing. July 2015 saw the first century break average, for the first time since at least 2006 (my spreadsheet doesn't go back further): 101,093 km2 per day on average.

And 2015 now has the most century breaks for the year to date: 44 (2013 is second with 43, and 2012 is third with 42 CBs).
Title: Re: 2015 sea ice area and extent data
Post by: andy_t_roo on August 01, 2015, 12:52:45 AM
From today's NSIDC data update I calculate the following CT updates (the days in this list are the days of data released, three days behind ice dates):

Thu       4.562689
Fri -30.1  4.532572
Sat -119.4  4.413175

Saturday's century is mostly the result of the CAB (-63k4). Smaller contributions from Baffin(-17k), CAA (-15k) and Laptev (-14k).

Some of the concentration drop seems to align with the heating over the north of CAA and the bordering CAB.

In the attached NSIDC delta map, pixels with larger concentration changes than 7% or colored pinkish (down) or light blue (up). Solid red and blue are where the pixel concentration crosses the 15% limit (for extent).
I'm surprised that there are significant concentration drops in what is traditionally the most solid ice area next to Greenland. That we have a low compactness isn't a surprise to me at all, given the way the ice is broken up but no strong melt front has been established.
Title: Re: 2015 sea ice area and extent data
Post by: DavidR on August 01, 2015, 01:26:43 AM
According to my  figures that  puts SIA at  second lowest;  just  50K km^2 above 2012. and NSIDC compaction (SIA/SIE) at 4.3% below 2012.  (66.2% vs 61.9%).

That  suggests there is plenty of room for further rapid reductions.
Are you sure about that second place? Using Wipneus' numbers, my records show CT SIA as 4th place for Day 0.5835, 371k behind 2012:

2012: 3,915,334 km2
2011: 4,186,187 km2
2007: 4,270,627 km2
2015: 4,285,889 km2

OTOH, 2015 SIA is now a pretty comfortable 512k ahead of 2013, and a remarkable 728k km2 ahead of 2014. (So much for the "rebound").

My take: 2015 almost certainly won't catch 2012; at this point, that would require an further loss of greater thasn 2 million km2. But beating 2007 for second is a very real possibility at this point; to do so, we'd need to see another 1.37 million km2 of loss over the next six weeks or so, an average of roughly 35k per day. (For the record, 2007 lost 1.35 million km2 between now and that year's maximum; 2013 dropped by an additional 1.244 million; 2014 lost another 1.53 million; and 2012 squeezed out another 1.68 million.)

Jim,
You are right. I have your figures listed for the 1st of August  ie day 213 or 0.5835 by Cryosphere's fascinating numbering system.  Wipneus's reference latest  figure is for day 211 which is Thursday 30th.  This could mean that I have aligned the dates for this year against actual dates and in previous years have still got the figures aligned against CT days.  (Checked that and thats what  has happened!! So do I  want the convenience of having the values listed against the same day as their extent  equivalents or do I  leave them misaligned!)
Title: Re: 2015 sea ice area and extent data
Post by: OldLeatherneck on August 01, 2015, 02:03:15 PM
During the last 16 days of July, the ADR-NIPR Sea Ice Extent lost a whopping 1,646,110 KM2, which is the most ever lost in the 2003-2014 time frame. Looking ahead to the first half of August, during the first 15 days the average losses are just over 70K/day. So if we see any century or near-century drops, we can gain ground against 2007 and 2011. For all practical purposes 2012's record will not be matched this year. It was August of that year when 2012 lost just sort of 2.6M KM2. Below are the current SIE chart as well as an updated table of simulated projections thru September 15th.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi1269.photobucket.com%2Falbums%2Fjj597%2FOldLeatherNeck%2FADR-NIPR%2520Arctic%2520sea%2520ice%2520extent%252031%2520July%25202015%2520Power%2520point_zpsbqycsa7j.jpg&hash=0baacb93adbef2c4ef10a308fd810665)

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi1269.photobucket.com%2Falbums%2Fjj597%2FOldLeatherNeck%2FADS-NIPR%2520Arctic%2520sea%2520ice%2520projections%252031%2520July%25202015_zpseu3k1912.jpg&hash=45007608c0f5480a8add89a2e103efff)
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on August 01, 2015, 04:25:23 PM
From today's NSIDC data update I calculate the following CT updates (the days in this list are the days of data released, three days behind ice dates):

Sat       4.413029
Sun -127.4  4.285616
Mon -39.7  4.245879

Only the ESS has a substantial contribution for Monday's slow decline: -19k8. The CAA  ice area even increased somewhat (+13k3).

In the attached NSIDC delta map, pixels with larger concentration changes than 7% or colored pinkish (down) or light blue (up). Solid red and blue are where the pixel concentration crosses the 15% limit (for extent).
Title: Re: 2015 sea ice area and extent data
Post by: seaicesailor on August 01, 2015, 05:05:09 PM

NSIDC SIE down around 90k
Title: Re: 2015 sea ice area and extent data
Post by: plg on August 01, 2015, 06:31:09 PM
From today's NSIDC data update I calculate the following CT updates (the days in this list are the days of data released, three days behind ice dates):

Sat       4.413029
Sun -127.4  4.285616
Mon -39.7  4.245879

Only the ESS has a substantial contribution for Monday's slow decline: -19k8. The CAA  ice area even increased somewhat (+13k3).

In the attached NSIDC delta map, pixels with larger concentration changes than 7% or colored pinkish (down) or light blue (up). Solid red and blue are where the pixel concentration crosses the 15% limit (for extent).

The last holdout for pre-2000 is 1999: 4.2044988. So in the very likely(?) event that Tuesday is over 41.4 k, then 2015 is firmly in 2000' territory (no surprise).
Title: Re: 2015 sea ice area and extent data
Post by: Subjectivist on August 02, 2015, 05:32:36 AM
As I understand it the cold fresh melt water is more buoyant than the salt water just beneath it so in calm conditions it floats on top and spread out in a very thin layer until mixing in and effectively dissipating.  However when high winds or stormy weather mixes things up the fresh melt water is quickly mixed into the saltier water just below dissipating it quickly.

Is this an accurate picture of how the mixing process works?

If so does the mixing slow down the formation of first year ice by removing the easily frozen fresh water from the surface layer?

TIA
Title: Re: 2015 sea ice area and extent data
Post by: LRC1962 on August 02, 2015, 01:37:09 PM
Mixing can cause more immediate surface ice melt. If no mixing occurs then the warmer salt water can got moved under the thicker ice causing it to lose its thickness. Now when freezing comes if the water is mixed then the heat from the water is lost to the air those freezing water faster. If on the othr hand you do have a layer of fresh water that will freeze , but the warmer salt water will take much longer to freeze and slow down the freezing process.
Very simplified explanation and probably missing some very important factors, but do believe that is the general idea what does happen.
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on August 02, 2015, 02:17:41 PM
ADS-NIPR Extent:
6,468,143 km2 (01 August)
Down 7,473,917 km2 (53.61%) from 2015 maximum of 13,942,060 km2 on 15 February.
3,290,688 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Down 95,719 km2 (-1.46%) from previous day.
Down 533,649 km2  (-7.62%) over past seven days (daily average: -76,236 km2).
Down 95,719 km2  (-1.46%) for August (daily average: -95,719 km2).
739,268 km2 below 2000s average for this date.
13,990 km2 below 2010s average for this date.
264,241 km2 below 2014 value for this date.
385,743 km2 above 2012 value for this date.
4th lowest August to-date average.
4th lowest value for the date.
64 days this year (30.05% year-to-date) have recorded the lowest daily extent.
32 days (15.02%) have recorded the second lowest.
32 days (15.02%) have recorded the third lowest.
128 days (60.09%) in total have been among the three lowest on record.


CT Area:
NOTE: due to infrequent updates of official CT sea ice area data, I'm using a combination of those official data and Wipneus' calculated area numbers. The official numbers will be inserted as they become available.
4,245,879 km2 (02 August [Day 0.5836])
Down 9,028,676 km2 (68.01%) from 2015 maximum of 13,274,555 km2 on 17 February [Day 0.1288].
2,011,870 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Down 40,010 km2 (-.93%) from previous day.
Down 512,395 km2 (-10.77%) over past seven days (daily average: -73,199 km2).
Down 167,296 km2 (-3.79%) for August (daily average: -83,648 km2).
819,742 km2 below 2000s average for this date.
133,049 km2 below 2010s average for this date.
624,353 km2 below 2014 value for this date.
458,683 km2 above 2012 value for this date.
4th lowest August to-date average.
4th lowest value for the date.
7 days this year (3.27% year-to-date) have recorded the lowest daily area.
19 days (8.88%) have recorded the second lowest.
29 days (13.55%) have recorded the third lowest.
55 days in total (25.7%) have been among the lowest three on record.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on August 02, 2015, 04:14:30 PM
From today's NSIDC data update I calculate the following CT updates (the days in this list are the days of data released, three days behind ice dates):

Sat       4.413029
Sun -127.4  4.285616
Mon -40.1  4.245564
Tue -119.6  4.125955

Yet another century on Tuesday, thanks goes to the contributors CAB (-35k7), Beaufort (-19k), CAA (-18k5), Baffin (-13k), Laptev (-11k) and Hudson (-10k).

It is the first of the month of course and some of the drops will be caused by the August ocean masks. My guess it is not much though.

In the attached NSIDC delta map, pixels with larger concentration changes than 7% or colored pinkish (down) or light blue (up). Solid red and blue are where the pixel concentration crosses the 15% limit (for extent).
Title: Re: 2015 sea ice area and extent data
Post by: BornFromTheVoid on August 02, 2015, 05:34:42 PM
Update for the week to August 1st

The current 5 day mean is on 6,943,200km2 while the 1 day extent is at 6,712,000km2.
The daily anomaly (compared to 81-10) is at -1,321,970km2, an increase from -1,306,980km2 last week. The anomaly compared to the 07, 11 and 12 average is at +365,200km2, a decrease from +438,553km2 last week. We're currently 5th lowest on record, up from 6th last week.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FXFz8pqI.png&hash=9e5ec30b03bb60cbd1d633f16c3c3469)

The average daily change over the last 7 days was -87.2k/day, compared to the long term average of -85.1k/day, and the 07, 11 and 12 average of -76.7k/day.
The average long term change over the next week is -74.7k/day, with the 07, 11, and 12 average being -92.6k/day.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FPDn7Jt0.png&hash=40bb0c338aee7f49078fdb5b84990520)

The loss so far this August is the 6th largest on record. To achieve the largest monthly drop, a daily loss of at least 89.0k/day is required, while the smallest drop requires a loss of no more than 37.8k/day and an average drop requires a loss of 55.7k/day.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FHo9OaET.png&hash=460d2369c0ea798814ae12428ac0479a)

The extent loss this July was the 4th largest on record, while the average extent was the 7th smallest on record.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FPJznmdU.png&hash=ed2c5d37f3164e9265f356476a5d2b79)

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2F9Gt68QW.png&hash=a94ed0a4933b449efdbafe2c528fd917)
Title: Re: 2015 sea ice area and extent data
Post by: seaicesailor on August 02, 2015, 07:06:49 PM
How misleading cold data can be sometimes:

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fnsidc.org%2Fdata%2Fseaice_index%2Fimages%2Fn_plot_hires.png&hash=6700f026eeb2c4c40016495a79bf6894)

You see this plot and the word "recovery", that is beyond rebound if you ignore statistics, may come to your mind.

And there is general agreement (almost certainty) that July has been one of the worst months for the ice, that the rebound years are gone and past, and that the state of the ice is really really bad

Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on August 03, 2015, 04:11:19 PM
From today's NSIDC data update I calculate the following CT updates (the days in this list are the days of data released, three days behind ice dates):

Mon       4.246491
Tue -119.7  4.126767
Wed +9.6  4.136411

A small increase this Wednesday, "caused" by "lake ice" increasing +14k5. Of the other regions only CAA changed significantly: -17k6.

In the attached NSIDC delta map, pixels with larger concentration changes than 7% or colored pinkish (down) or light blue (up). Solid red and blue are where the pixel concentration crosses the 15% limit (for extent).
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on August 04, 2015, 04:18:43 PM
From today's NSIDC data update I calculate the following CT updates (the days in this list are the days of data released, three days behind ice dates):

Tue       4.126390
Wed +9.6  4.136031
Thu -52.2  4.083793

The semi-century drop on Thursday came with help from lake ice (-12k8). Conventional regions that contributed are CAA (-13k3) and Beaufort (-10k5).

Extent drops are much bigger especially in the Beaufort and the bordering part of the CAB where all these stretches of open water are now being captured by  the (relatively) coarse grid used by NSIDC.
 
In the attached NSIDC delta map, pixels with larger concentration changes than 7% or colored pinkish (down) or light blue (up). Solid red and blue are where the pixel concentration crosses the 15% limit (for extent).
Title: Re: 2015 sea ice area and extent data
Post by: seaicesailor on August 04, 2015, 06:17:26 PM
I must add that the NSIDC SIE fell 400K during the past four days.
 
Title: Re: 2015 sea ice area and extent data
Post by: Jim Pettit on August 05, 2015, 01:14:37 PM
ADS-NIPR Extent:
6,221,434 km2 (04 August)
Down 7,720,626 km2 (55.38%) from 2015 maximum of 13,942,060 km2 on 15 February.
3,043,979 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Down 59,364 km2 (-.95%) from previous day.
Down 572,436 km2  (-8.43%) over past seven days (daily average: -81,777 km2).
Down 342,428 km2  (-5.22%) for August (daily average: -85,607 km2).
779,671 km2 below 2000s average for this date.
38,487 km2 below 2010s average for this date.
293,025 km2 below 2014 value for this date.
432,934 km2 above 2012 value for this date.
4th lowest August to-date average.
4th lowest value for the date.
64 days this year (29.63% year-to-date) have recorded the lowest daily extent.
32 days (14.81%) have recorded the second lowest.
32 days (14.81%) have recorded the third lowest.
128 days (59.26%) in total have been among the three lowest on record.


CT Area:
NOTE: due to infrequent updates of official CT sea ice area data, I'm using a combination of those official data and Wipneus' calculated area numbers. The official numbers will be inserted as they become available.
4,083,793 km2 (05 August [Day 0.5918])
Down 9,190,762 km2 (69.24%) from 2015 maximum of 13,274,555 km2 on 17 February [Day 0.1288].
1,849,784 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Down 52,618 km2 (-1.27%) from previous day.
Down 478,896 km2 (-10.5%) over past seven days (daily average: -68,414 km2).
Down 329,236 km2 (-7.46%) for August (daily average: -65,847 km2).
795,017 km2 below 2000s average for this date.
107,425 km2 below 2010s average for this date.
566,886 km2 below 2014 value for this date.
527,561 km2 above 2012 value for this date.
4th lowest August to-date average.
4th lowest value for the date.
7 days this year (3.23% year-to-date) have recorded the lowest daily area.
19 days (8.76%) have recorded the second lowest.
29 days (13.36%) have recorded the third lowest.
55 days in total (25.35%) have been among the lowest three on record.

As of now, 2015 area has fallen below the annual minima recorded in every year prior to and including 2005, with the lone exception of 2002.
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on August 05, 2015, 04:08:06 PM
From today's NSIDC data update I calculate the following CT updates (the days in this list are the days of data released, three days behind ice dates):

Wed       4.134669
Thu -54.3  4.080380
Fri -47.7  4.032717

The next semi-century this Friday has as major supporters the CAB (-34k2) and CAA (-28k4). Kara saw a small increase (+10k).

In the attached NSIDC delta map, pixels with larger concentration changes than 7% or colored pinkish (down) or light blue (up). Solid red and blue are where the pixel concentration crosses the 15% limit (for extent).
Title: Re: 2015 sea ice area and extent data
Post by: Wipneus on August 06, 2015, 04:46:53 PM
(A shortened report, I am traveling and on Android)

CT's area value due to be released Saturday is estimated to 4.0099 (-21k2). Almost the same loss as the CAB
Title: Re: 2015 sea ice area and extent data
Post by: plinius on August 06, 2015, 04:59:13 PM
and overall extent essentially stalled for today (0.01 increase).
Title: Re: 2015 sea ice area and extent data
Post by: plg on August 06, 2015, 07:45:46 PM