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Wipneus

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Re: 2015 sea ice area and extent data
« Reply #950 on: August 28, 2015, 04:17:06 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):

day   chg  estimate  CT-value
Fri        3.543364  3.543492
Sat -45.8  3.497596  -
Sun -85.9  3.411718  -

CAB is the main player again: -62k4, for the rest only the CAA changed significantly at -10k7.

(for NSIDC extent those numbers are -99k8 and -38k)

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).

OldLeatherneck

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Re: 2015 sea ice area and extent data
« Reply #951 on: August 28, 2015, 05:47:56 PM »
Updated Near-Term ADS-NIPR SIE Loss Projections

The simplistic model I developed for projecting near-term SIE losses assumes that the melt season would end on the 15th of September. That was not a random choice. In the past 12 years the earliest minimum was on the 9th and the latest was on the 21st, while six years ended before the 15th, 5 years ended after the 15th and one lone year ended on the 15th. I have no way of knowing whether 2015 will end before or after the 15th. Just because dramatic losses are occurring this week and there are elevated SSTs on the fringes of the ice pack is no guarantee that melting will continue later than normal. The other reason for ending on the 15th is that it is almost impossible to determine average daily losses during a time when SIE values may be fluctuating up or down on a daily basis.

I will also cross-post this on the IJIS thread.

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Yuha

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Re: 2015 sea ice area and extent data
« Reply #952 on: August 28, 2015, 07:00:02 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):

day   chg  estimate  CT-value
Fri        3.543364  3.543492
Sat -45.8  3.497596  -
Sun -85.9  3.411718  -


With this the recent increase has been nearly completely wiped out.
A drop of less than 20k is needed to reach a new minimum.

Jim Pettit

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Re: 2015 sea ice area and extent data
« Reply #953 on: August 29, 2015, 12:46:17 PM »
ADS-NIPR Extent:
4,526,408 km2 (28 August)
Down 9,415,652 km2 (67.53%) from 2015 maximum of 13,942,060 km2 on 15 February.
1,348,953 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Down 58,561 km2 (-1.28%) from previous day.
Down 611,566 km2  (-11.9%) over past seven days (daily average: -87,367 km2).
Down 2,037,454 km2  (-31.04%) for August (daily average: -72,766 km2).
1,242,650 km2 below 2000s average for this date.
205,887 km2 below 2010s average for this date.
717,388 km2 below 2014 value for this date.
939,733 km2 above 2012 value for this date.
4th lowest August to-date average.
3rd lowest value for the date.
64 days this year (26.67% year-to-date) have recorded the lowest daily extent.
32 days (13.33%) have recorded the second lowest.
35 days (14.58%) have recorded the third lowest.
131 days (54.58%) 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'm using a combination of those official data and Wipneus' calculated area numbers. The official numbers will be inserted as they become available.
3,411,718 km2 (29 August [Day 0.6576])
Down 9,862,837 km2 (74.3%) from 2015 maximum of 13,274,555 km2 on 17 February [Day 0.1288].
1,177,709 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Down 85,301 km2 (-2.44%) from previous day.
Down 116,007 km2 (-3.29%) over past seven days (daily average: -16,572 km2).
Down 1,001,311 km2 (-22.69%) for August (daily average: -34,528 km2).
716,209 km2 below 2000s average for this date.
75,254 km2 above 2010s average for this date.
505,766 km2 below 2014 value for this date.
889,294 km2 above 2012 value for this date.
4th lowest August to-date average.
6th lowest value for the date.
7 days this year (2.9% year-to-date) have recorded the lowest daily area.
19 days (7.88%) have recorded the second lowest.
30 days (12.45%) have recorded the third lowest.
56 days in total (23.24%) have been among the lowest three on record.

Wipneus

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Re: 2015 sea ice area and extent data
« Reply #954 on: August 29, 2015, 04:13:17 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):

day   chg  estimate  CT-value
Sat        3.497596  3.497019
Sun -85.9  3.411681  -
Mon -32.5  3.379164  -

Back to low declines ("lake ice" helped here with a drop of -13k4) it seems. CAA had a loss of -15k4 , followed by the CAB with -13k.

By extent CAA and CAB scored -43k2 and -25k5. Beaufort did a rebounce 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).

Wipneus

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Re: 2015 sea ice area and extent data
« Reply #955 on: August 31, 2015, 04:12:01 PM »
(if you are looking for the report from Sunday, 30 August, it is not there. NSIDC skipped the update.)

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):

day   chg  estimate  CT-value
Sun        3.411681  3.410435
Mon -31.8  3.379930  -
Tue -30.9  3.349044  -
Wed -22.6  3.326412  -

Small changes,  only "lakes" changed significantly: -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).

BornFromTheVoid

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Re: 2015 sea ice area and extent data
« Reply #956 on: August 31, 2015, 05:12:01 PM »
Update for the week to August 29th

The current 5 day mean is on 4,889,600km2 while the 1 day extent is at 4,687,000km2.
The daily anomaly (compared to 81-10) is at -1,760,580km2, an increase from -1,562,860km2 last week. The anomaly compared to the 07, 11 and 12 average is at +428,000km2, a decrease from +543,067km2 last week. We're currently 4th lowest on record, the same as last week.



The average daily change over the last 7 days was -70.4k/day, compared to the long term average of -42.0k/day, and the 07, 11 and 12 average of -53.9k/day.
The average long term change over the next week is -36.8k/day, with the 07, 11, and 12 average being -42.6k/day.



The loss so far this August is the 5th largest on record. To achieve the largest monthly drop, a daily loss of at least 308.6k/day is required, while the smallest drop requires an increase of more than 457.5k/day and an average drop requires an increase of 191.1k/day.


ael

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Re: 2015 sea ice area and extent data
« Reply #957 on: August 31, 2015, 07:24:49 PM »
Wipneus, I am confused by the picture.

It looks like Lake Michigan just melted out near Chicago.
That seems wrong. 

Are the instruments really that bad at reading ice extent,
or am I misreading something?

plinius

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Re: 2015 sea ice area and extent data
« Reply #958 on: August 31, 2015, 07:29:38 PM »
that bad in shallow waters and near coastlines, e.g. also tidal variations. Think the actually most important impact there is the Siberian alluvial regions.

Wipneus

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Re: 2015 sea ice area and extent data
« Reply #959 on: September 01, 2015, 08:26:42 AM »
Wipneus, I am confused by the picture.

It looks like Lake Michigan just melted out near Chicago.
That seems wrong. 

Are the instruments really that bad at reading ice extent,
or am I misreading something?

The instruments have their limitations, yes. Land spillover due to the large field of view of the microwave antenna is one factor, waves another.
Normally this gets (some) compensation for sea ice, but since it is lakes they are not included.

NSIDC does not include lake ice in its sea ice extent numbers, so there is no problem there. CT-area does include it, adding to the problems that this measure already has.

Jim Pettit

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Re: 2015 sea ice area and extent data
« Reply #960 on: September 01, 2015, 12:21:48 PM »
ADS-NIPR Extent:
4,438,696 km2 (31 August)
Down 9,503,364 km2 (68.16%) from 2015 maximum of 13,942,060 km2 on 15 February.
1,261,241 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Down 53,211 km2 (-1.18%) from previous day.
Down 483,204 km2  (-9.82%) over past seven days (daily average: -69,029 km2).
Down 2,125,166 km2  (-32.38%) for August (daily average: -68,554 km2).
1,234,978 km2 below 2000s average for this date.
201,002 km2 below 2010s average for this date.
779,566 km2 below 2014 value for this date.
929,310 km2 above 2012 value for this date.
4th lowest August average.
3rd lowest value for the date.
64 days this year (26.34% year-to-date) have recorded the lowest daily extent.
32 days (13.17%) have recorded the second lowest.
38 days (15.64%) have recorded the third lowest.


CT Area:
NOTE: due to inconsistent 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.
3,326,412 km2 (01 September [Day 0.6658])
Down 9,948,143 km2 (74.94%) from 2015 maximum of 13,274,555 km2 on 17 February [Day 0.1288].
1,092,403 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Down 22,632 km2 (-.68%) from previous day.
Down 271,285 km2 (-7.54%) over past seven days (daily average: -38,755 km2).
Down 22,632 km2 (-.68%) for September (daily average: -22,632 km2).
722,425 km2 below 2000s average for this date.
52,042 km2 above 2010s average for this date.
380,118 km2 below 2014 value for this date.
816,326 km2 above 2012 value for this date.
6th lowest September to-date average.
6th lowest value for the date.
7 days this year (2.87% year-to-date) have recorded the lowest daily area.
19 days (7.79%) have recorded the second lowest.
30 days (12.3%) have recorded the third lowest.
56 days in total (22.95%) have been among the lowest three on record.

« Last Edit: September 01, 2015, 01:12:17 PM by Jim Pettit »

crandles

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Re: 2015 sea ice area and extent data
« Reply #961 on: September 01, 2015, 12:30:20 PM »
3,326,412 km2 (01 September [Day 0.6658])
4th lowest September to-date average.
6th lowest value for the date.

minor correction:
6th lowest September to date average, I think.

Jim Pettit

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Re: 2015 sea ice area and extent data
« Reply #962 on: September 01, 2015, 01:11:00 PM »
3,326,412 km2 (01 September [Day 0.6658])
4th lowest September to-date average.
6th lowest value for the date.

minor correction:
6th lowest September to date average, I think.

Yes. A newly-automated component had a glitch; it's been fixed. Thanks.

OldLeatherneck

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Re: 2015 sea ice area and extent data
« Reply #963 on: September 01, 2015, 02:50:49 PM »
ADS-NIPR SIE Looking Ahead to September

From the 15th to the 31st of August ADS SIE lost 1,084,109 Km2 which surpassed the record set by 2012 of 1,039,852 Km2.

Currently, 2015 is in 3rd place, 57,133 Km2 below 2011 and only 24,736 Km2 above 2007.

The least amount of SIE loss in September was 149,981 Km2 in 2004. The most amount of SIE loss was 501,822 Km2 in 2010.  The average loss was 290,986 Km2.

I'm reasonably certain that 2015 will end the season in at least 3rd place, below 2011.  Also, 2015 has a reasonable opportunity to end the season in 2nd place below 2007.



« Last Edit: September 01, 2015, 03:01:38 PM by OldLeatherneck »
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Wipneus

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Re: 2015 sea ice area and extent data
« Reply #964 on: September 01, 2015, 04:10:12 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):

day   chg  estimate  CT-value
Tue        3.349044  3.348241
Wed -22.7  3.326389  -
Thu  -3.1  3.323282  -

Without the small decline of lake ice (-7k) that would have been an uptick. Everything quiet, ESS changed most, -10k2.

By extent, CAB dropped a -52k1 (the area increased by +8k).

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).

BornFromTheVoid

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Re: 2015 sea ice area and extent data
« Reply #965 on: September 01, 2015, 04:51:11 PM »
Daily NSIDC extent now just 54k away from securing the 4th lowest minimum on record.

Using the 5 day average, the loss from June 30th to August 31st (5,484,800km2) was the 3rd largest on record, just behind 2007 (5,568,200km2) and 2012 (5,793,400km2).

The loss over the last 2 weeks has been the largest on record.

Wipneus

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Re: 2015 sea ice area and extent data
« Reply #966 on: September 02, 2015, 04:13:44 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):

day   chg  estimate  CT-value
Wed        3.326389  3.325811
Thu  -3.1  3.323291  -
Fri -106.9  3.216355  -

A late century decline is helped no doubt due to the first of the month effect: Okhotsk scored -11k5, "others" including Gulf of Alaska -9k5. The CAB will not be affected and dropped a solid -38k8. Baffin and Hudson may be affected, they changed by -14k and -12k4.

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).

Bill Fothergill

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Re: 2015 sea ice area and extent data
« Reply #967 on: September 02, 2015, 07:22:00 PM »
As a brief addendum to the CT SIA derivation performed by Wipneus on the NSIDC data for the 1st September, the Charctic 5-day average is now just 57k above the lowest value it attained during 2008.

Unless tomorrow's NSIDC SIE daily figure jumps upward by about 35k, then, as of September 2nd, 2015 will have the 4th lowest minimum on their 5-day metric.

In fact, even if the NSIDC SIE numbers for the 2nd and 3rd of September exhibit 2 consecutive 80k up-ticks, the 2008 5-day minimum will still be surpassed on the 3rd of the month.

Bill Fothergill

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Re: 2015 sea ice area and extent data
« Reply #968 on: September 03, 2015, 04:27:49 PM »
....

Unless tomorrow's NSIDC SIE daily figure jumps upward by about 35k, then, as of September 2nd, 2015 will have the 4th lowest minimum on their 5-day metric.

...

Ha! It went up 34k.

The Charctic rolling 5-day value stands at 4.586 million sq kms as at the 2nd September.
The 2008 minimum using this metric occurred on the 20th September, and its value was, wait for it, 4.586 million sq kms. Fourth lowest place has to wait one more day. (Unless tomorrow's one-day value goes up by about 125k .)

Wipneus

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Re: 2015 sea ice area and extent data
« Reply #969 on: September 03, 2015, 04:38:49 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):

day   chg  estimate  CT-value
Thu        3.323291  3.322530
Fri -107.0  3.216280  -
Sat -16.3  3.199950  -

Just the CAB changed significantly: -35k4.

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

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Re: 2015 sea ice area and extent data
« Reply #970 on: September 04, 2015, 05:48:16 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):

day   chg  estimate  CT-value
Fri        3.216280  3.215496
Sat -16.2  3.200086  -
Sun -73.7  3.126379  -

Only the CAB changed significantly: -75k.

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).

Jim Pettit

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Re: 2015 sea ice area and extent data
« Reply #971 on: September 05, 2015, 02:36:53 PM »
ADS-NIPR Extent:
4,368,949 km2 (04 September)
Down 9,573,111 km2 (68.66%) from 2015 maximum of 13,942,060 km2 on 15 February.
1,191,494 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Up 250 km2 (.01%) from previous day.
Down 157,459 km2  (-3.48%) over past seven days (daily average: -22,494 km2).
Down 69,747 km2  (-1.57%) for September (daily average: -17,437 km2).
1,220,564 km2 below 2000s average for this date.
171,331 km2 below 2010s average for this date.
773,863 km2 below 2014 value for this date.
954,899 km2 above 2012 value for this date.
2nd lowest September to-date average.
3rd lowest value for the date.
64 days this year (25.91% year-to-date) have recorded the lowest daily extent.
35 days (14.17%) have recorded the second lowest.
39 days (15.79%) have recorded the third lowest.
138 days in total (55.87%) have been among the lowest three on record.


CT Area:
NOTE: due to inconsistent 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.
3,126,379 km2 (05 September [Day 0.6768])
Down 10,148,176 km2 (76.45%) from 2015 maximum of 13,274,555 km2 on 17 February [Day 0.1288].
892,370 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Down 74,128 km2 (-2.32%) from previous day.
Down 284,056 km2 (-8.33%) over past seven days (daily average: -40,579 km2).
Down 221,862 km2 (-6.63%) for September (daily average: -44,372 km2).
848,811 km2 below 2000s average for this date.
30,383 km2 below 2010s average for this date.
499,883 km2 below 2014 value for this date.
762,846 km2 above 2012 value for this date.
6th lowest September to-date average.
5th lowest value for the date.
7 days this year (2.82% year-to-date) have recorded the lowest daily area.
19 days (7.66%) have recorded the second lowest.
30 days (12.1%) have recorded the third lowest.
56 days in total (22.58%) have been among the lowest three on record.

Wipneus

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Re: 2015 sea ice area and extent data
« Reply #972 on: September 05, 2015, 04:05:50 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):

day   chg  estimate  CT-value
Sat        3.200086  3.200507
Sun -73.6  3.126522  -
Mon +38.0  3.164499  -

Again it is the CAB where the area changes are made: +32k7

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

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Re: 2015 sea ice area and extent data
« Reply #973 on: September 06, 2015, 04:46:05 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):

day   chg  estimate  CT-value
Sun        3.126522  3.126571
Mon +38.1  3.164575  -
Tue  -9.2  3.155363  -

No significant change in any of the 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).

BornFromTheVoid

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Re: 2015 sea ice area and extent data
« Reply #974 on: September 06, 2015, 05:42:51 PM »
Update for the week to September 5th

The current 5 day mean is on 4,483,600km2 while the 1 day extent is at 4,464,000km2.
The daily anomaly (compared to 81-10) is at -1,908,690km2, an increase from -1,760,580km2 last week. The anomaly compared to the 07, 11 and 12 average is at +319,867km2, a decrease from +428,000km2 last week. We're currently 3rd lowest on record,  up from 4th lowest last week.



The average daily change over the last 7 days was -58.k/day, compared to the long term average of -36.8k/day, and the 07, 11 and 12 average of -42.6k/day.
The average long term change over the next week is -16.1k/day, with the 07, 11, and 12 average being -20.6k/day.



The change so far this September is the 8th most negative on record. To achieve the largest monthly drop, a daily loss of at least 5.2k/day is required, while the largest monthly growth requires an increase of at least 37.9k/day and an average change requires an increase of 14.9k/day.



The extent loss in August was the 3rd largest on record, while the average extent was the 4th smallest on record.




Jim Pettit

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Re: 2015 sea ice area and extent data
« Reply #975 on: September 07, 2015, 01:22:11 PM »
ADS-NIPR Extent:
4,349,431 km2 (06 September)
Down 9,592,629 km2 (68.8%) from 2015 maximum of 13,942,060 km2 on 15 February.
1,171,976 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Down 24,374 km2 (-.56%) from previous day.
Down 142,476 km2  (-3.17%) over past seven days (daily average: -20,354 km2).
Down 89,265 km2  (-2.01%) for September (daily average: -14,878 km2).
1,198,305 km2 below 2000s average for this date.
122,053 km2 below 2010s average for this date.
700,938 km2 below 2014 value for this date.
1,024,193 km2 above 2012 value for this date.
3rd lowest September to-date average.
4th lowest value for the date.
64 days this year (25.7% year-to-date) have recorded the lowest daily extent.
35 days (14.06%) have recorded the second lowest.
39 days (15.66%) have recorded the third lowest.
138 days in total (55.42%) have been among the lowest three on record.


CT Area:
NOTE: due to inconsistent 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.
3,155,363 km2 (07 September [Day 0.6823])
Down 10,119,192 km2 (76.23%) from 2015 maximum of 13,274,555 km2 on 17 February [Day 0.1288].
921,354 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Down 9,212 km2 (-.29%) from previous day.
Down 192,878 km2 (-5.76%) over past seven days (daily average: -27,554 km2).
Down 192,878 km2 (-5.76%) for September (daily average: -27,554 km2).
807,103 km2 below 2000s average for this date.
42,215 km2 above 2010s average for this date.
450,780 km2 below 2014 value for this date.
857,153 km2 above 2012 value for this date.
6th lowest September to-date average.
6th lowest value for the date.
7 days this year (2.8% year-to-date) have recorded the lowest daily area.
19 days (7.6%) have recorded the second lowest.
30 days (12.%) have recorded the third lowest.
56 days in total (22.4%) have been among the lowest three on record.

Wipneus

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Re: 2015 sea ice area and extent data
« Reply #976 on: September 07, 2015, 05:29:24 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):

day   chg  estimate  CT-value
Sun        3.126522  3.126571
Mon +38.1  3.164575  -
Tue  -9.8  3.154784  -
Wed -44.5  3.110306  -

CAB is the region: -34k2.

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

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Re: 2015 sea ice area and extent data
« Reply #977 on: September 08, 2015, 04:10:51 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):

day   chg  estimate  CT-value
Tue        3.154784  3.153750
Wed -44.3  3.110501  -
Thu -15.9  3.094641  -

CAB is the region: -13k7

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).

seaicesailor

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Re: 2015 sea ice area and extent data
« Reply #978 on: September 08, 2015, 05:04:30 PM »

SIE -87k now at 4.378 mil km2

This is very close (+45k) to the 2011 non-averaged daily minimum (which was on Sep 8 as today)

2011,    09,  08,      4.333



Jim Pettit

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Re: 2015 sea ice area and extent data
« Reply #979 on: September 08, 2015, 07:32:42 PM »
FWIW, Day 0.6876--the most recent one for which Wipneus has provided Arctic sea ice area numbers--was the day on which the annual minimums were recorded in 1980, 1981, 1993, and 2010. The minimums recorded in 1983, 1986, 1987, 1988, 1992, 1994, 2002, 2003, and 2007 have already been passed. Still to come; the minimums recorded in:

2008 and 2009 (+1)
2000, 2011, 2013, and 2014 (+2)
1990 and 1998 (+4)
1982 and 1985 (+5)
2012 (+6)
1989 (+7)
1999 (+9)
2001 (+10)
1991 (+11)
1984 (+13)
1997 and 2006 (+15)
1995 (+22)

Here's a quick and dirty look at the normal normal distribution for minimum days:



In other words: if 2015 hasn't hit bottom yet, it doesn't have much farther to go...

Ninebelowzero

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Re: 2015 sea ice area and extent data
« Reply #980 on: September 08, 2015, 09:54:29 PM »
Would there be a time when the amount of heat build up in the Arctic system delays refreeze.

magnamentis

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Re: 2015 sea ice area and extent data
« Reply #981 on: September 08, 2015, 10:14:15 PM »
that's exactly what i'm expecting sooner or later, could be very much sooner than many think. after all there is a lot of energy in the system which is dispersed until there is nowhere to "hide" LOL let's see but i share your feel for what's coming. similarly i see the antarctic situation. there are a few factors which compensate so we don't see the build up of events but i expect a sudden drop as well down there. it's like many physical thresholds, once they let go it's like a dam brakes. the situation becomes more and more enthralling each time.
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BornFromTheVoid

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Re: 2015 sea ice area and extent data
« Reply #982 on: September 09, 2015, 12:02:25 PM »
Below are the rankings for 925hPa air temperatures north of 72.5N, based on the ncep reanalysis since 1948.

Year    May..June...July.Aug.MJJA
2007   22.....2......4.....3.....3
2008   8......19....12....4.....8
2009   19....40.....9....17....17
2010   1.......6.....25....9.....5
2011   7.......5.....1.....2.....1
2012   5.......4.....6....10.....4
2013   30....38....15...34....30
2014   28....41....38...18....31
2015   27....11.....2....26....13

2015 comes out as the 13th mildest on record. (For anyone wondering where 2nd place overall is, it is 2005).
« Last Edit: September 09, 2015, 03:43:22 PM by BornFromTheVoid »

crandles

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Re: 2015 sea ice area and extent data
« Reply #983 on: September 09, 2015, 12:16:10 PM »
High pressure over weak areas starting Friday. Just time to get below 2010's 3.072 before area starts rising again I would think. 2008's 3.004 being reachable looks much more dubious (even though only 91k below latest 3.095)?

Perhaps this year a similar date for extent minimum as for area minimum?

(I keep changing my mind so don't trust my forecasts. First I had early area minimum late extent minimum due to low capie then with high capie I had both being early now I have typical area minimum date and early extent minimum date. Maybe such changes in forecasts are not too bad - CAPIE information changed and weather was always likely to trump CAPIE information and I said so with first such prediction. Doesn't give an impression of reliable forecasts though.)


Jim Pettit

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Re: 2015 sea ice area and extent data
« Reply #984 on: September 09, 2015, 12:55:03 PM »
ADS-NIPR Extent:
4,297,543 km2 (08 September)
Down 9,644,517 km2 (69.18%) from 2015 maximum of 13,942,060 km2 on 15 February.
1,120,088 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Down 10,161 km2 (-.24%) from previous day.
Down 77,469 km2  (-1.77%) over past seven days (daily average: -11,067 km2).
Down 141,153 km2  (-3.18%) for September (daily average: -17,644 km2).
1,227,897 km2 below 2000s average for this date.
126,520 km2 below 2010s average for this date.
729,725 km2 below 2014 value for this date.
996,748 km2 above 2012 value for this date.
3rd lowest September to-date average.
4th lowest value for the date.
64 days this year (25.5% year-to-date) have recorded the lowest daily extent.
35 days (13.94%) have recorded the second lowest.
39 days (15.54%) have recorded the third lowest.
138 days in total (54.98%) have been among the lowest three on record.


CT Area:
NOTE: due to inconsistent 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.
3,094,641 km2 (09 September [Day 0.6876])
Down 10,179,914 km2 (76.69%) from 2015 maximum of 13,274,555 km2 on 17 February [Day 0.1288].
860,632 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Down 15,483 km2 (-.5%) from previous day.
Down 227,889 km2 (-6.86%) over past seven days (daily average: -32,556 km2).
Down 253,600 km2 (-7.57%) for September (daily average: -28,178 km2).
845,570 km2 below 2000s average for this date.
3,366 km2 below 2010s average for this date.
482,053 km2 below 2014 value for this date.
753,471 km2 above 2012 value for this date.
6th lowest September to-date average.
6th lowest value for the date.
7 days this year (2.78% year-to-date) have recorded the lowest daily area.
19 days (7.54%) have recorded the second lowest.
30 days (11.9%) have recorded the third lowest.
56 days in total (22.22%) have been among the lowest three on record.
« Last Edit: September 09, 2015, 01:15:46 PM by Jim Pettit »

OldLeatherneck

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Re: 2015 sea ice area and extent data
« Reply #985 on: September 09, 2015, 01:54:49 PM »
Only a few more days of reasonable losses for 2015 to go below 2011's annual minimum.  Unless some very surprising weather event occurs, 2007 seems to be out of reach this year.

9,618 Km2 above 2011 and 103,022 Km2 above 2007 for this date.

28,344 Km2 above  2011’s  annual minimum and 231,784 Km2 above 2007’s annual minimum.

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seaicesailor

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Re: 2015 sea ice area and extent data
« Reply #986 on: September 09, 2015, 02:37:04 PM »
Below are the rankings for 925hPa air temperatures north of 72.5N, based on the ncep reanalysis for since 1948.

[...]


Extremely interesting statistics!!

Compare 2011 and 2015

Year    May..June...July.Aug.MJJA
2011   7.......5.....1.....2.....1
2015   27....11.....2....26....13

These years shared similarities since the beginning of the season (remember Vid?). Even the shape of the final pack has a lot in common. And July month.

However see August 26th position! And yet the huge wreck that three weak cold storms caused over the already broken MYI Beaufort ice, and the compaction from the relatively cold Laptev area. Then the final storm.

And May in 27th position, which saw a warmth wave in Alaska and Canada, with South winds that opened up the Beaufort sea and Chukchi kicking in albedo effect, a preconditioning element that, in absence of it, melting would have been delayed.

Then snow cover preconditioning due to Winter weather. Not accounted for in these statistics.

Overall averaged temperatures are extremely misleading. Local temperatures 850hpa-925hpa and land surface temps can be significant though, especially in Peripheral areas during May-June.

This year we also had the out-of-mind hot Pacific and the few systems it brought to the Arctic, sometimes via North America, sometimes warm advection, other times not-so-warm systems like the big Chukchi August storm. You can have more and more heat being transported to the Arctic Ocean, under what seems overall cool temperatures. Then the ocean stores heat and releases it later in the season.

As discussed recently in this forum, the pulses of heat expansion in the Equator due to El Niño directly translate to pulses of inflow at the Bering Strait. No need for an ocean current requiring years to reach the Arctic. Any small element of expansion due to temperature increase at the Equator creates a sound wave (1NM/s) which reaches and funnels in Bering in 2 hours and immediately generates a flow pulse into the Arctic due to the difference of pressure. But more importantly, it creates slower gravitational waves (same kind as the tsunami waves) that travel to Bering in a matter of one day and contribute to sea level increase. Therefore, sea level at Bering would increase at the same pace as El Niño temperatures increase. However, water spills into the Arctic moderating sea level increase but leading to enhanced currents into the coasts of Alaska and Siberia. IIRC very early bottom melting was observed near the coasts. And East Siberian Coast opened up very quickly even when it was late and cold. Temperatures at Chukchi and Beaufort are, no doubt, really warm for the year. So although this effect may be small, it may have helped trigger the retreat of ice, so important for albedo amplification, and contributed to bottom melting in key areas.

PS. I have been convinced this is not correct :--)
The rest are observations about facts happening during this melting season

« Last Edit: September 09, 2015, 05:05:00 PM by seaicesailor »

plinius

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Re: 2015 sea ice area and extent data
« Reply #987 on: September 09, 2015, 03:58:51 PM »
greeat - what you always consider as "ascertained/discussed/found in this forum". May I remind you that there is vast literature on the Bering flow, and that it does not really confirm your rather crude claims?

Edit: My kudos, seaicesailor, if I may say that turn is an impressive example how people in here still value facts more than being right about something (and giving me something to strive for).  Also sorry if my comment was a bit harsh ;-).
« Last Edit: September 09, 2015, 07:22:55 PM by plinius »

BornFromTheVoid

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Re: 2015 sea ice area and extent data
« Reply #988 on: September 09, 2015, 04:00:59 PM »
Daily NSIDC extent has now dropped below the 2011 minimum, so guaranteeing at least the 3rd lowest minimum on record. It's now just 194k off the 2007 minimum in 2nd place.

EDIT: Misread, we're actually 8k above 2011....d'oh!
« Last Edit: September 09, 2015, 04:06:32 PM by BornFromTheVoid »

Wipneus

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Re: 2015 sea ice area and extent data
« Reply #989 on: September 09, 2015, 04:19:30 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):

day   chg  estimate  CT-value
Wed        3.110501  3.110124
Thu -15.9  3.094609  -
Fri  +8.0  3.102642  -


Lakes (+10k) helped to cause this uptick. Greenland Sea went up (+18k), CAA down (-13k4).

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).

seaicesailor

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Re: 2015 sea ice area and extent data
« Reply #990 on: September 09, 2015, 04:30:15 PM »
greeat - what you always consider as "ascertained/discussed/found in this forum". May I remind you that there is vast literature on the Bering flow, and that it does not really confirm your rather crude claims?

No

seaicesailor

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Re: 2015 sea ice area and extent data
« Reply #991 on: September 09, 2015, 05:06:09 PM »
greeat - what you always consider as "ascertained/discussed/found in this forum". May I remind you that there is vast literature on the Bering flow, and that it does not really confirm your rather crude claims?

Removed the part concerning the Bering Flow - Niño correlation and its effect on ice within the Arctic proper. Thank you.

plinius

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Re: 2015 sea ice area and extent data
« Reply #992 on: September 09, 2015, 07:15:00 PM »
thanks ;-)

Bruce Steele

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Re: 2015 sea ice area and extent data
« Reply #993 on: September 09, 2015, 07:24:15 PM »
Seaicesailor, Don't give it up so easy my friend. I think the conditions of the early Ice conditions in the Bering did influence the melt season this year. I believe the low ice extent in the Bering was very much influenced by the PDO however rather than the El Nino. Chris did a very nice post on Dosbat explaining the positions of the low and high pressure systems that resulted in south to north wind conditions for the late 2014 early 2015 season in the Bering and Chukchi. His post also shows a chart of positive and negative sea ice conditions for the Bering Sea.

 http://dosbat.blogspot.com/2015/01/where-is-ice-in-bering-sea.html

If you look at the PDO 2004 and 2005 as well as the 2014 and 2015 seasons you will see low Bering Sea ice anomalies aligned with strongly positive PDO index numbers.

http://research.jisao.washington.edu/pdo/PDO.latest

So PDO very likely influences the position of a low pressure setting up over the Asian continent and a
high pressure over the Aleutians. This dipole then pulls warm air from the south and delivers it to the Bering and Chukchi. We will likely see a some strong PDO numbers at least through spring of next year so a similar dipole and wind conditions may set up again next melt season ( Dec. 2015 thru Feb. 2016)These conditions do influence the strength of the currents through the Bering Strait. There is always a pressure head forcing water north through the Straits but strong north to south wind condition can weaken or temporarily reverse that flow.  Southerly flow strengthens it and so too leads to early ice melt conditions on the Pacific side.
« Last Edit: September 09, 2015, 08:20:41 PM by Bruce Steele »

seaicesailor

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Re: 2015 sea ice area and extent data
« Reply #994 on: September 09, 2015, 09:29:57 PM »
Bruce thank you very much for the great explanation of PDO effect on Bering sea, this was real science. I don't give up , lol, it is just that Plinius has a point. I love to speculate, have my small bit of knowledge and let my imagination play with it. Not making things up, but relying too much on easy reasoning without quantifying  :--). My view of heat expansion effect is not incorrect but how much its influence is, probably very small if scientists do not find the sort of correlation I was implying.
Should be less passionate, sit down and do some numbers. And find time to read. But do what you can with what you have, we only live once.
Its all good!

opensheart

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Re: 2015 sea ice area and extent data
« Reply #995 on: September 09, 2015, 10:58:55 PM »
BornFromTheVoid
we're actually 8k above 2011..

Wipneus
day   chg  estimate  CT-value
Wed        3.110501  3.110124
Thu -15.9  3.094609  -
Fri  +8.0  3.102642  -

So if Wed we were 8K above 2011
and Thur we decline 15.9k,  which would be 7.9K  below 2011
but then Fri rises 8k,
and with adjustments, margins of error, etc

Are we ending up in a statistical tie with 2011?

seaicesailor

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Re: 2015 sea ice area and extent data
« Reply #996 on: September 09, 2015, 11:08:38 PM »
BornFromTheVoid
we're actually 8k above 2011..

Wipneus
day   chg  estimate  CT-value
Wed        3.110501  3.110124
Thu -15.9  3.094609  -
Fri  +8.0  3.102642  -

So if Wed we were 8K above 2011
and Thur we decline 15.9k,  which would be 7.9K  below 2011
but then Fri rises 8k,
and with adjustments, margins of error, etc

Are we ending up in a statistical tie with 2011?

I believe BFTV was referring to NSIDC sea ice extent, not area.

ftp://sidads.colorado.edu/DATASETS/NOAA/G02135/north/daily/data/NH_seaice_extent_nrt.csv

DavidR

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Re: 2015 sea ice area and extent data
« Reply #997 on: September 09, 2015, 11:16:32 PM »
BornFromTheVoid
we're actually 8k above 2011..

Wipneus
day   chg  estimate  CT-value
Wed        3.110501  3.110124
Thu -15.9  3.094609  -
Fri  +8.0  3.102642  -

So if Wed we were 8K above 2011
and Thur we decline 15.9k,  which would be 7.9K  below 2011
but then Fri rises 8k,
and with adjustments, margins of error, etc

Are we ending up in a statistical tie with 2011?
opensheart
you  are confusing the extent figures with area figures.   We are currently 8K above the 2011 minimum with up to two weeks of potential decline.   The CT Area figures are still a bit above the minimums for the 2nd to  5th  loweest  years but  any  of them are acheivable in the unlikely  event  of a week of strong melt. ,   

plinius

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Re: 2015 sea ice area and extent data
« Reply #998 on: September 10, 2015, 12:57:36 AM »
@Bruce: Anecdotal evidence with cherry-picked dates does never make for good evidence. I am not even aware how the positive PDO (which gives warm water in front of the american coast, but cooling effect on the surface below Bering) should impact the Bering strait much else than by a windstress vector that is rather directed _out_ of the arctic, but maybe you can explain this, perhaps with some typical image:


Bruce Steele

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Re: 2015 sea ice area and extent data
« Reply #999 on: September 10, 2015, 04:21:38 AM »
Plinius, Anecdotal evidence with cherry picked dates sounds kinda pissy to me and sharp elbows do not a good rebuttal make so maybe if you read the Dosbat link and go thru the years 79,79,82
84,85,86,96,97and2003 you will see they are also positive PDO index years with negative Bering sea ice 
anomalies.  When we have negative sea ice anomalies in the Bering the date of warm water entering thru the Straits advances if weather conditions line up for larger early season south to north water/wind flow like the conditions Chris described in Phase three of the linked Dosbat post. He also has nice pictures if that's what you'd like to see.
 I picked the years 2004-2005 and 2014-2015 because they are positive PDO index numbers in a cold water phase of the PDO highlighting the importance IMO of the PDO on Bering Sea negative Ice anomalies and an early start to melting season in the Chukchi.