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Author Topic: 2016 sea ice area and extent data  (Read 277415 times)

Jim Pettit

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Re: 2016 sea ice area and extent data
« Reply #600 on: August 02, 2016, 05:07:21 PM »
Here is the shadow CT-area report based on calibrated F18 NSIDC sea ice concentration data:

day  CT-date       NH               SH                Global
Mon 2016.5781  -40.1  4.281226 +156.9 13.572847  +116.8 17.854073
Tue 2016.5808 -144.1  4.137164 +187.3 13.760145   +43.2 17.897309
Wed 2016.5836  -97.1  4.040073 -114.9 13.645262  -212.0 17.685335
Thu 2016.5863  -90.9  3.949171  -36.5 13.608778  -127.4 17.557949


Thanks, Wipneus. That drops 2016 to-date SIA lower than the absolute minima recorded in every year prior to 2007 (1979-2006). With 5-6 weeks left, beating out 2013 (3.55M), 2014 (3.48M), and 2009 (3.43M) should be easy. Then we should eventually get to the tight cluster of years including 2007, 2008, 2010, 2011, and 2015, which all lie within 190k of each other. Then, far below and almost certainly untouchable, sits 2012.

Wipneus

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Re: 2016 sea ice area and extent data
« Reply #601 on: August 03, 2016, 05:37:38 PM »
Here is the shadow CT-area report based on calibrated F18 NSIDC sea ice concentration data:

day  CT-date       NH               SH                Global
Tue 2016.5808 -144.1  4.137164 +187.3 13.760145   +43.2 17.897309
Wed 2016.5836  -97.1  4.040073 -114.9 13.645262  -212.0 17.685335
Thu 2016.5863  -90.9  3.949134  -36.2 13.609103  -127.1 17.558237
Fri 2016.5890  +18.2  3.967332 +103.7 13.712817  +121.9 17.680149


The uptick is mostly caused by the CAB (+28k) and CAA (+14k).

Shadow NSIDC extent is now  6.3851 dropping -116.6k. Some big declines in Laptev (-60k), Kara (-35k), Baffin (-28k) and Beaufort (-25k). The CAA went opposite (+33k).

There is a delta map for the graphical touch.

BornFromTheVoid

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Re: 2016 sea ice area and extent data
« Reply #602 on: August 04, 2016, 04:04:16 PM »
A drop of 188k takes the daily NSIDC extent down to 2nd lowest on record.

It also puts the 7 day loss up to 942k, and means that we only have to average a 138k drop over the next 2 days to achieve a mega melt week (>1,000,000km2).

Using the 5 days average, we have now dropped below the minima of 14 previous years,  1979-1983, 1986-1989, 1992, 1994, 1996, 1997 and 2001


Wipneus

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Re: 2016 sea ice area and extent data
« Reply #603 on: August 04, 2016, 06:23:15 PM »
Here is the shadow CT-area report based on calibrated F18 NSIDC sea ice concentration data:

day  CT-date       NH               SH                Global
Wed 2016.5836  -97.1  4.040073 -114.9 13.645262  -212.0 17.685335
Thu 2016.5863  -90.9  3.949134  -36.2 13.609103  -127.1 17.558237
Fri 2016.5890  +17.6  3.966762 +104.1 13.713220  +121.7 17.679982
Sat 2016.5918  -37.6  3.929124 +195.1 13.908352  +157.5 17.837476



An uptick in the CAB (+38k) is the cause for a small total. Laptev (-22k) and CAA (-17k) are the biggest decliners.

Shadow NSIDC extent is now 6.1973 dropping -187.8k. Laptev keeps falling hard (-56k), followed by CAA (-39k), Baffin (-29k) and Beaufort (-25k).

Where ice cover grows, where it shrinks, see it on the attached delta map.

Wipneus

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Re: 2016 sea ice area and extent data
« Reply #604 on: August 05, 2016, 04:39:03 PM »
Here is the shadow CT-area report based on calibrated F18 NSIDC sea ice concentration data:

day  CT-date       NH               SH                Global
Thu 2016.5863  -90.9  3.949134  -36.2 13.609103  -127.1 17.558237
Fri 2016.5890  +17.6  3.966762 +104.1 13.713220  +121.7 17.679982
Sat 2016.5918  -37.6  3.929124 +195.1 13.908299  +157.4 17.837423
Sun 2016.5945   -4.2  3.924892  +37.6 13.945875   +33.3 17.870767

Only small regional changes, Laptev (-15k) and CAA (+15k) changed most.

Shadow NSIDC extent is now 6.2668  nd increase of +69.6k. Laptev  and CAA caused the rebound (both +46k). The ESS did compensate a bit with -33k.

That can all be seen in the attached delta map.

Juan C. García

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Re: 2016 sea ice area and extent data
« Reply #605 on: August 06, 2016, 04:58:43 AM »
Seems that today we have an important ASI compaction and/or flash melt.

First image from , Neven ASI Blog

Which is the best answer to Sep-2012 ASI lost?
50% [NSIDC extent vs 1979-2000] or
80% [Orig. PIOMAS volume vs 1979, 77.6% with corrections]

Volume is harder to measure than extent, but 3D is real, 2D's hide ~50% thickness gone.
-> IPCC/NSIDC official trends underestimate the real speed of ASI lost.

S.Pansa

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Re: 2016 sea ice area and extent data
« Reply #606 on: August 06, 2016, 06:06:06 AM »
Seems that today we have an important ASI compaction and/or flash melt.
 ...]

Looking at this area with NASA Worldview it seems to me that most of the concentration-change is due to a change in cloud cover (see the two pics below). If you zoom in you can see that there is definitely some melting going on. But the changes do not look that massive between the 4th and 5th - at least to my eyes.

Glenn Tamblyn

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Re: 2016 sea ice area and extent data
« Reply #607 on: August 06, 2016, 10:38:28 AM »
Juan

Flash melt maybe, but the second graph looks suspect. That is a strange near vertical line where the concentration suddenly transitions from 70's to 90's. Given how much lower area there was on the first graph that looks strange. Artifact from a satellite pass?

Juan C. García

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Re: 2016 sea ice area and extent data
« Reply #608 on: August 06, 2016, 03:15:41 PM »
S. Pansa & Glenn Tamblyn:

You read my second thought about this picture (I went to bed thinking about it). Seems that there has been a lot of change on Chukchi, East Siberian Sea and even the Arctic Basin, but at the same time, some floes stayed at the same place, like they did not moved with currents or winds. Seems that the satellite is mistakenly taking clouds as ice on the right side of Chukchi. We will have to wait for the next Bremen pictures (to keep the same source).
« Last Edit: August 06, 2016, 03:30:34 PM by Juan C. García »
Which is the best answer to Sep-2012 ASI lost?
50% [NSIDC extent vs 1979-2000] or
80% [Orig. PIOMAS volume vs 1979, 77.6% with corrections]

Volume is harder to measure than extent, but 3D is real, 2D's hide ~50% thickness gone.
-> IPCC/NSIDC official trends underestimate the real speed of ASI lost.

Wipneus

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Re: 2016 sea ice area and extent data
« Reply #609 on: August 06, 2016, 05:14:50 PM »

day  CT-date       NH               SH                Global
Fri 2016.5890  +17.6  3.966762 +104.1 13.713220  +121.7 17.679982
Sat 2016.5918  -37.6  3.929124 +195.1 13.908299  +157.4 17.837423
Sun 2016.5945   -4.4  3.924752  +37.5 13.945810   +33.1 17.870562
Mon 2016.5973 -123.6  3.801130   -2.3 13.943550  -125.9 17.744680

All the work of CAB (-64k), ESS (-28k) and Laptev (-24k).

Shadow NSIDC extent is now 6.1836 dropping  -83.2. Only one mighty lifter to mention:
ESS with -57k. Hudson went elsewhere and rebounded +25k.

I have attached the delta map for another vieuw.

Juan C. García

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Re: 2016 sea ice area and extent data
« Reply #610 on: August 07, 2016, 04:23:57 AM »
Back to normal (not all that ice). The Arctic sea ice melt is advancing...

Thanks Wipneus, for your daily information!
I don´t like the "Seems..." in my previous messages! Your information clearly quantifies the looses!
Which is the best answer to Sep-2012 ASI lost?
50% [NSIDC extent vs 1979-2000] or
80% [Orig. PIOMAS volume vs 1979, 77.6% with corrections]

Volume is harder to measure than extent, but 3D is real, 2D's hide ~50% thickness gone.
-> IPCC/NSIDC official trends underestimate the real speed of ASI lost.

Rob Dekker

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Re: 2016 sea ice area and extent data
« Reply #611 on: August 07, 2016, 07:58:34 AM »
Thank you Juan,

I think it was seaicesailor who first noted that the ice north-north-east of Wrangel island showed a "path" of weak ice, with holes forming along the way north, and he suggested this had to do with ocean currents from the Bering.

I found this image of the currents out of the Bering Strait into the Arctic, and I think seaicesailor does have a point : There is a current out of the Bering that flows right next to (to the east of) Wrangel island, through "Harald Valley" and due north, which matches with the location where (at least on AMSR) Arctic sea ice is forming increasingly large polynia :



Elsewhere I found that this current is called "Anadyr" water, and since it comes directly out of the Bering, it can very well have contributed to the weakening of the ice along the current (by bottom melt) which now culminates in dropping off the AMSR2 radar.

This does not bode well for the ice in that area, which is already extremely fragmented as JayW's animations clearly show.

slow wing

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Re: 2016 sea ice area and extent data
« Reply #612 on: August 07, 2016, 08:34:30 AM »
Very interesting, Rob and SeaIceSailor, thanks!

seaicesailor

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Re: 2016 sea ice area and extent data
« Reply #613 on: August 07, 2016, 12:03:32 PM »
Thank you Juan,

I think it was seaicesailor who first noted that the ice north-north-east of Wrangel island showed a "path" of weak ice, with holes forming along the way north, and he suggested this had to do with ocean currents from the Bering.

I found this image of the currents out of the Bering Strait into the Arctic, and I think seaicesailor does have a point : There is a current out of the Bering that flows right next to (to the east of) Wrangel island, through "Harald Valley" and due north, which matches with the location where (at least on AMSR) Arctic sea ice is forming increasingly large polynia :
...
Elsewhere I found that this current is called "Anadyr" water, and since it comes directly out of the Bering, it can very well have contributed to the weakening of the ice along the current (by bottom melt) which now culminates in dropping off the AMSR2 radar.

This does not bode well for the ice in that area, which is already extremely fragmented as JayW's animations clearly show.
Hey Rob thank you! I was waiting to download another image later this week.
Right now the polynya is being moved laterally with the ice. We'll see if the ocean opens up again in the previous location, but anyway the polynya is so huge now that we may end up not seeing a thing.

Jim Pettit

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Re: 2016 sea ice area and extent data
« Reply #614 on: August 07, 2016, 01:44:15 PM »
ADS-NIPR Extent:
5,868,941 km2 (06 August)
Down 8,073,566 km2 (57.91%) from 2016 maximum of 13,942,507 km2 on 29 February.
2,691,486 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Down 93,189 km2 (-1.56%) from previous day.
Down 665,397 km2  (-10.18%) over past seven days (daily average: -95,057 km2).
Down 569,169 km2  (-4.65%) for August (daily average: -94,862 km2).
988,410 km2 below 2000s average for this date.
217,865 km2 below 2010s average for this date.
283,861 km2 below 2015 value for this date.
374,805 km2 above 2012 value for this date.
Lowest year-to-date (01 January - 06 August) average.
3rd lowest August to-date average.
3rd lowest value for the date.
128 days this year (58.72% year-to-date) have recorded the lowest daily extent.
35 days (16.06%) have recorded the second lowest.
29 days (13.3%) have recorded the third lowest.
192 days in total (88.07%) have been among the lowest three on record.


CT Area:
3,801,130 km2 (06 August [Day 0.5973])
Down 9,120,228 km2 (70.58%) from 2016 maximum of 12,921,358 km2 on 29 March [Day 0.2384].
1,567,121 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Down 123,622 km2 (-3.15%) from previous day.
Down 480,096 km2 (-11.6%) over past seven days (daily average: -68,585 km2).
Down 480,096 km2 (-4.31%) for August (daily average: -68,585 km2).
1,018,109 km2 below 2000s average for this date.
238,507 km2 below 2010s average for this date.
150,878 km2 below 2015 value for this date.
375,763 km2 above 2012 value for this date.
* - NOTE: due to the prolonged absence of official CT sea ice area data, I've incorporated Wipneus' shadow area numbers as calculated from NSIDC data. The official numbers will be inserted if/when available. In the meantime, thanks, Wipneus!






Bill Fothergill

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Re: 2016 sea ice area and extent data
« Reply #615 on: August 07, 2016, 02:23:06 PM »
Thank you Juan,

I think it was seaicesailor who first noted that the ice north-north-east of Wrangel island showed a "path" of weak ice, with holes forming along the way north, and he suggested this had to do with ocean currents from the Bering.
...

...
Right now the polynya is being moved laterally with the ice. We'll see if the ocean opens up again in the previous location, but anyway the polynya is so huge now that we may end up not seeing a thing.


Yep, that's certainly getting closer to just being open water.

On the other hand, for the last 10 days or so, I've being watching the beginnings of a polynya stretching from the Vilkitsky Strait in the direction of the New Siberian Islands. In that time, not much has really developed, but there is a specific reason for the interest in that particular region.

You may be aware of the Polar Ocean Challenge: in which the 15-metre, aluminium skinned yacht, Northabout, is attempting a single season, West-to-East circumnavigation of both the Northern Sea Route and the Northwest Passage. For the last week, Northabout has been anchored at Ostrov Pilota Makhotkina, in the Nordenskiöld Archipelago waiting for the passage into the Laptev to open up.

seaicesailor

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Re: 2016 sea ice area and extent data
« Reply #616 on: August 07, 2016, 03:42:36 PM »
Paper by R Woodgate and others about the role of anomalous heat flux on the ice extent loss in 2007
http://psc.apl.washington.edu/HLD/Bstrait/BS2007Heat.html
Very much on-topic given the current amount of ice under menace in Chukchi and around. Potentially could be responsible of up to 2 m. km2 in the entire melting season. Not saying this is the case this year, but gives an idea that its effect may become quite visible.
One of the effects that this heat flux can cause is a persistence of heat transport around and beneath the ice during fall and winter given that it takes time for the Bering inflow to slow down or even reverse. HYCOM shows a recent acceleration of the inflow, possibly due to prevalent Northwards winds in the current weather pattern. Dilated melting season then?

« Last Edit: August 07, 2016, 03:59:32 PM by seaicesailor »

Wipneus

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Re: 2016 sea ice area and extent data
« Reply #617 on: August 07, 2016, 04:27:03 PM »
Here is the shadow CT-area report based on calibrated F18 NSIDC sea ice concentration data:

day  CT-date       NH               SH                Global
Sat 2016.5918  -37.6  3.929124 +195.1 13.908299  +157.4 17.837423
Sun 2016.5945   -4.4  3.924752  +37.5 13.945810   +33.1 17.870562
Mon 2016.5973 -123.7  3.801093   -2.2 13.943580  -125.9 17.744673
Tue 2016.6000 -125.5  3.675573  -37.8 13.905788  -163.3 17.581361


It happened in the CAB: -134k. "Lakes" went up +31k (no doubt all false ice, CT is what it is).

Shadow NSIDC extent is now 6.0675 dropping -116.1k. CAB was the main decliner (-37k) followed by Hudson (-20k), Laptev (-18k) and Greenland Sea (-16k).

Attached is the delta map of the day.

Steven

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Re: 2016 sea ice area and extent data
« Reply #618 on: August 07, 2016, 04:39:48 PM »
Here is the shadow CT-area report based on calibrated F18 NSIDC sea ice concentration data:

2016.6000  ...   3.675573 


Currently 2nd lowest.  It is 335k above 2012,   19k below 2011,  and 157k below 2007:


TerryM

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Re: 2016 sea ice area and extent data
« Reply #619 on: August 07, 2016, 07:52:58 PM »
Wipneus
With shore temperatures as high as 25C at the southern end of James Bay I think it's safe to consider that there is no more ice building or busting in Hudson Bay than there is in Lake Erie. Worldview appears to agree that clouds are the only extant white patches.
Terry

BornFromTheVoid

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Re: 2016 sea ice area and extent data
« Reply #620 on: August 08, 2016, 12:58:20 PM »
Update for the week to August 6th

The current 5 day trailing average is on 6,220,000km2 while the 1 day extent is at 6,067,000km2.

(All the following data is based on a trailing 5 day average)
The daily anomaly (compared to 81-10) is at -1,659,000km2, an increase from -1,462,000km2 last week. The anomaly compared to the 07, 11 and 12 average is at +63,000km2, a decrease from +272,000km2 last week. We're currently 3rd lowest on record, up from 4th last week.



The average daily change over the last 7 days was -107.4k/day, compared to the long term average of -79.4k/day, and the 07, 11 and 12 average of -77.5k/day.
The average long term change over the next week is -66.0k/day, with the 07, 11, and 12 average being -98.9k/day.



The extent loss so far this August is the 2nd largest on record. To achieve the largest monthly loss, a drop of at least 85.1k/day is required (requiring ~85.8k/day with with single day values), while the smallest loss requires a drop less than 23.7k/day (<19.1k with single day values) and an average loss requires a drop of 45.0k/day (~42.3k/day with single day values).



The extent loss in July was the 18th smallest on record, while the average extent was the 3rd lowest on record.




BornFromTheVoid

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Re: 2016 sea ice area and extent data
« Reply #621 on: August 08, 2016, 01:08:50 PM »


Some stats on the difference between the current 5 day extent and previous minima

Diff.............No of Years.....Percentage
Below..............18.............48.6%
+0-100k............1..............2.7%
+100-250k.........4.............10.8%
+250-500k.........3..............8.1%
+500-1000k.......2..............5.4%
>1000k.............9.............24.3%

Wipneus

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Re: 2016 sea ice area and extent data
« Reply #622 on: August 08, 2016, 04:31:16 PM »
Here is the shadow CT-area report based on calibrated F18 NSIDC sea ice concentration data:

day  CT-date       NH               SH                Global
Sun 2016.5945   -4.4  3.924752  +37.5 13.945810   +33.1 17.870562
Mon 2016.5973 -123.7  3.801093   -2.2 13.943580  -125.9 17.744673
Tue 2016.6000 -124.7  3.676421  -37.7 13.905869  -162.4 17.582290
Wed 2016.6027   +2.0  3.678457   -3.7 13.902207    -1.6 17.580664


None of the regions changed noteworthy.

Shadow NSIDC extent is now 5.9610 dropping -106.5. Highest decliner was the CAB (-50k), followed by Hudson (-23k), CAA (-17k) and Chukchi (-16k).

Have a look at the attached delta map and see what the opening of a "bite" looks like

Neven

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Re: 2016 sea ice area and extent data
« Reply #623 on: August 08, 2016, 04:41:26 PM »
Flash-unflash-flash-unflash?  :)

Bumpy ride...
Il faut cultiver notre jardin

Juan C. García

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Re: 2016 sea ice area and extent data
« Reply #624 on: August 08, 2016, 04:48:06 PM »
Flash-unflash-flash-unflash?  :)

Bumpy ride...

It is notorious the difference between area change and extent change. While area did not change, we have a century drop in extent!
Which is the best answer to Sep-2012 ASI lost?
50% [NSIDC extent vs 1979-2000] or
80% [Orig. PIOMAS volume vs 1979, 77.6% with corrections]

Volume is harder to measure than extent, but 3D is real, 2D's hide ~50% thickness gone.
-> IPCC/NSIDC official trends underestimate the real speed of ASI lost.

Siffy

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Re: 2016 sea ice area and extent data
« Reply #625 on: August 08, 2016, 05:06:34 PM »
Flash-unflash-flash-unflash?  :)

Bumpy ride...

More like Unflash, flash, flash, unflash.

 :P

Jim Pettit

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Re: 2016 sea ice area and extent data
« Reply #626 on: August 08, 2016, 05:33:02 PM »
Here is the shadow CT-area report based on calibrated F18 NSIDC sea ice concentration data:

day  CT-date       NH               SH                Global
Sun 2016.5945   -4.4  3.924752  +37.5 13.945810   +33.1 17.870562
Mon 2016.5973 -123.7  3.801093   -2.2 13.943580  -125.9 17.744673
Tue 2016.6000 -124.7  3.676421  -37.7 13.905869  -162.4 17.582290
Wed 2016.6027   +2.0  3.678457   -3.7 13.902207    -1.6 17.580664

That still leaves 2016 in second place, though barely ahead of 2007 (which went on to lose more than half a million km2 of area over the next week, including a near double century drop). Perhaps more meaningfully, however, the gap between first place 2012 and 2016 has widened to its largest yet at 475k, thanks to the former year's much-talked-about GAC. The effects of the GAC were over on 0.6028, however, so there's a chance to play a little catch-up. Having said that, though, first place is firmly out of reach at this point, with just 4-5 weeks left to lose 1.45M km2. I do think second place is probable. There's a massive lead of 671k between first place 2012 and current second place 2011, so this year needs to see a further drop of "just" 774k, a not unreasonable amount: only one year in the past ten (2006) has failed to see that much additional area loss from here onward, and the average drop from now through annual minimum for those same ten years has been 927k.

Wipneus

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Re: 2016 sea ice area and extent data
« Reply #627 on: August 08, 2016, 06:46:31 PM »
Flash-unflash-flash-unflash?  :)

Bumpy ride...

Time of year when temperatures hoovering around freezing point. The daily cycle of temperatures gets more prominent as well. Since the satellite orbits do not exactly repeat after 24 hours, I speculate there may be a cause and effect.

animation needs a click to start

Wipneus

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Re: 2016 sea ice area and extent data
« Reply #628 on: August 09, 2016, 04:35:27 PM »
Here is the shadow CT-area report based on calibrated F18 NSIDC sea ice concentration data:

day  CT-date       NH               SH                Global
Mon 2016.5973 -123.7  3.801093   -2.2 13.943580  -125.9 17.744673
Tue 2016.6000 -124.7  3.676421  -37.7 13.905869  -162.4 17.582290
Wed 2016.6027   +2.0  3.678457   -4.0 13.901830    -2.0 17.580287
Thu 2016.6055   -8.9  3.669541  +60.2 13.962020   +51.3 17.631561


CAB area increased +32k. Other regions changed little.

Shadow NSIDC extent is 5.9239  dropping -37.1k. The CAB changed -28k, CAA trailed at -18k. Baffin increased +22k.

The attached delta map shows exactly where the changes are taking place.

Pmt111500

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Re: 2016 sea ice area and extent data
« Reply #629 on: August 09, 2016, 06:07:54 PM »
Flash-unflash-flash-unflash?  :)

Bumpy ride...

Time of year when temperatures hoovering around freezing point. The daily cycle of temperatures gets more prominent as well. Since the satellite orbits do not exactly repeat after 24 hours, I speculate there may be a cause and effect.

animation needs a click to start

This. You get a pretty stable curve averaging over 2 weeks but the n you lose all the interesting discussion on ups and downs, which could still be real but not as pronounced as the raw numbers state... I in fact dug the orbital period of the satellite in question out and thought to use a multiple of that as the averaging period but never got to it. The easy to do 13 or 15 day weighted averages were enough for me, as it looked like it pretty much smoothed the weather effects out. 
« Last Edit: August 09, 2016, 06:50:54 PM by Pmt111500 »
A quantity relates to a quantum like camel's back relates to camel's _______ ? (back, vertebra, vertebral tendon, spinal disc, paralysis)

Wipneus

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Re: 2016 sea ice area and extent data
« Reply #630 on: August 10, 2016, 06:40:57 PM »
Here is the shadow CT-area report based on calibrated F18 NSIDC sea ice concentration data:

day  CT-date       NH               SH                Global
Tue 2016.6000 -124.7  3.676421  -37.7 13.905869  -162.4 17.582290
Wed 2016.6027   +2.0  3.678457   -4.0 13.901830    -2.0 17.580287
Thu 2016.6055   -9.0  3.669434  +59.6 13.961410   +50.6 17.630844
Fri 2016.6082  -49.8  3.619676   -5.6 13.955855   -55.3 17.575531


The only region that changed enough for me to mention is "lakes". A lot of spurious ice  disappeared there: -18k.

Shadow NSIDC extent is now 5.9060 dropping  -17.9. The CAB lost -32k, CAA -18k but the Hudson increased +34k.

It can all been seen in the delta map that is attached.

Nick_Naylor

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Re: 2016 sea ice area and extent data
« Reply #631 on: August 10, 2016, 07:24:15 PM »
The image seems to be showing a downward arrow. Probably an omen that area and extent are going to take a bit of a dive the next few days.

seaice.de

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SIPN Webinar on uncertainty in sea ice extent
« Reply #632 on: August 11, 2016, 07:30:02 AM »
The Sea Ice Prediction Network (SIPN) announces a call for registration
for an open webinar entitled "Uncertainty in Satellite-Derived Sea Ice
Extent Estimates" presented by Walt Meier, NASA Goddard Space Flight
Center. This event is scheduled for Tuesday, 23 August 2016
from 10:00 a.m. to 11:00 a.m. AKDT.
We request that all participants pre-register to join any SIPN webinar.
Anyone with an e-mail address can register, and participation is free.
To register for this webinar, go to:
https://www.arcus.org/sipn/meetings/webinars/register.

This webinar is designed for the sea ice research community and others
interested in information about the uncertainty in sea ice extent
estimates from remotely-sensed data. While this is an open event,
attendees should be aware that the discussions will largely be of a
technical nature. The speaker will be Walt Meier, NASA Goddard Space
Flight Center.

Walt Meier is a research scientist at the NASA Goddard Space Flight
Center Cryospheric Sciences Laboratory. His research focuses on remote
sensing of sea ice, development of new sea ice products and sea ice
climate data records, and analyzing changes in the Arctic sea ice cover.
He has been principal investigator on a project to create a sea ice
climate data record.

Meier’s presentation will focus on uncertainty in sea ice extent
estimates from remotely-sensed data. Arctic sea ice extent estimates
from remote sensing data (e.g., passive microwave sensors like Advanced
Microwave Scanning Radiometer-Earth Observing System [AMSR-E] and
others) are widely used to project sea ice trends, initialize models,
and evaluate model forecasts. As with all kinds of remote observations,
this method of estimating sea ice extent has strengths and weaknesses
that result in unique kinds of uncertainty. To date, however, little
effort has been made to provide an uncertainty range of extent estimates
from satellite data. Meier will discuss our current understanding of
these issues and propose various methods of estimating extent
uncertainty, with the aim of improving analyses of sea ice extent trends
and variability. Time for participant questions will follow the
presentation.

The webinar is scheduled for 10:00 a.m. to 11:00 a.m. AKDT (11:00 a.m.to
12:00 p.m. PDT, 12:00 p.m. to 1:00 p.m. MDT, 1:00-2:00 p.m. CDT, and
2:00-3:00 p.m. EDT) on Tuesday, 23 August 2016.

The webinar will be archived and available online after the event.

Wipneus

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Re: 2016 sea ice area and extent data
« Reply #633 on: August 11, 2016, 04:20:30 PM »
Here is the shadow CT-area report based on calibrated F18 NSIDC sea ice concentration data:

day  CT-date       NH               SH                Global
Wed 2016.6027   +2.0  3.678457   -4.0 13.901830    -2.0 17.580287
Thu 2016.6055   -9.0  3.669434  +59.6 13.961410   +50.6 17.630844
Fri 2016.6082  -49.9  3.619535   -5.3 13.956136   -55.2 17.575671
Sat 2016.6110  -12.4  3.607119  -51.9 13.904270   -64.3 17.511389


CAB increased by +50k. Area decreased in the CAA (-23k) and Laptev (-17k).

Shadow NSIDC extent is now 5.7651 dropping -140.9k. The decline is led by CAA (-44k) followed by Hudson (-22k), Chukchi (-20k) and ESS (-18k).

As always the attached delta map may help to understand the numbers.

BornFromTheVoid

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Re: 2016 sea ice area and extent data
« Reply #634 on: August 12, 2016, 04:19:39 PM »
Another large drop on the daily NSIDC extent, -142k. This takes us just 33k off 2007 in 2nd place, but still over 600k above 2012.

With the 5 day average, we've now dropped below 23 of the 37 previous minima. This includes all minima up to and including 1998, as well as 2000, 2001 and 2003. We're within 250k of 1999, 2002, 2004 and 2006 minima too.

« Last Edit: August 12, 2016, 06:11:05 PM by BornFromTheVoid »

Wipneus

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Re: 2016 sea ice area and extent data
« Reply #635 on: August 12, 2016, 06:02:45 PM »
Here is the shadow CT-area report based on calibrated F18 NSIDC sea ice concentration data:

day  CT-date       NH               SH                Global
Thu 2016.6055   -9.0  3.669434  +59.6 13.961410   +50.6 17.630844
Fri 2016.6082  -49.9  3.619535   -5.3 13.956136   -55.2 17.575671
Sat 2016.6110  -12.6  3.606984  -45.9 13.910256   -58.4 17.517240
Sun 2016.6137  +29.5  3.636496  +29.0 13.939217   +58.5 17.575713


Big increases in the CAB: +89k. ESS (-22k) and CAA(-19k) cannot prevent an uptick.

Shadow NSIDC extent is now 5.6227 dropping -142.5k. Laptev is the leader: -48k, followed by CAA (-36k), Hudson (-36k), ESS (-23k) and Greenland Sea (-16k). The extent in the CAB increased +25k.

The attached delta map shows where the extent and area changes came from.

Jim Pettit

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Re: 2016 sea ice area and extent data
« Reply #636 on: August 12, 2016, 08:10:57 PM »
Here is the shadow CT-area report based on calibrated F18 NSIDC sea ice concentration data:

day  CT-date       NH               SH                Global
Thu 2016.6055   -9.0  3.669434  +59.6 13.961410   +50.6 17.630844
Fri 2016.6082  -49.9  3.619535   -5.3 13.956136   -55.2 17.575671
Sat 2016.6110  -12.6  3.606984  -45.9 13.910256   -58.4 17.517240
Sun 2016.6137  +29.5  3.636496  +29.0 13.939217   +58.5 17.575713


That will drop 2016 back into 5th place behind 2012, 2011, 2015, and 2007. This will be the first time since January that 2016 trailed last year.

The current stall is reminiscent with the nine-day one that took place in the second week of August in 2014, where CT area flatlined, actually increasing by a total of 15k over the period (before falling by nearly 800k before the month ended).

Bill Fothergill

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Re: 2016 sea ice area and extent data
« Reply #637 on: August 13, 2016, 01:01:32 PM »
For any readers relatively new to the subject, the side-by-side layout for area and extent used by the Nansen Environmental & Remote Sensing Centre rather neatly illustrates the point made by Jim Pettit - even including the way 2014 went walk-about in August 2014.

http://arctic-roos.org/observations/ice-area-and-extent-in-arctic

NB Unfortunately, as Nansen uses a sliding window approach to the times series, 2007 is no longer getting displayed, but it would, of course, be second to 2012 in area/extent around the time of the September minimum.

Jim Pettit

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Re: 2016 sea ice area and extent data
« Reply #638 on: August 13, 2016, 03:05:31 PM »
ADS-NIPR Extent:
5,420,490 km2 (12 August)
Down 8,522,017 km2 (61.12%) from 2016 maximum of 13,942,507 km2 on 29 February.
2,243,035 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Down 73,342 km2 (-1.33%) from previous day.
Down 541,640 km2  (-9.08%) over past seven days (daily average: -77,377 km2).
Down 1,017,620 km2  (-8.32%) for August (daily average: -84,802 km2).
1,082,297 km2 below 2000s average for this date.
201,538 km2 below 2010s average for this date.
242,491 km2 below 2015 value for this date.
626,976 km2 above 2012 value for this date.
Lowest year-to-date (01 January - 12 August) average.
3rd lowest August to-date average.
3rd lowest value for the date.
128 days this year (57.14% year-to-date) have recorded the lowest daily extent.
35 days (15.63%) have recorded the second lowest.
35 days (15.63%) have recorded the third lowest.
198 days in total (88.39%) have been among the lowest three on record.


CT Area:
3,636,496 km2 (12 August [Day 0.6136])
Down 9,284,862 km2 (71.86%) from 2016 maximum of 12,921,358 km2 on 29 March [Day 0.2384].
1,402,487 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Up 29,512 km2 (.82%) from previous day.
Down 288,256 km2 (-7.58%) over past seven days (daily average: -41,179 km2).
Down 644,730 km2 (-5.79%) for August (daily average: -49,595 km2).
905,509 km2 below 2000s average for this date.
142,760 km2 below 2010s average for this date.
49,754 km2 above 2015 value for this date.
523,395 km2 above 2012 value for this date.
* - NOTE: due to the prolonged absence of official CT sea ice area data, I've incorporated Wipneus' shadow area numbers as calculated from NSIDC data. The official numbers will be inserted if/when available. In the meantime, thanks, Wipneus!

Wipneus

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Re: 2016 sea ice area and extent data
« Reply #639 on: August 13, 2016, 05:07:44 PM »
Here is the shadow CT-area report based on calibrated F18 NSIDC sea ice concentration data:

day  CT-date       NH               SH                Global
Fri 2016.6082  -49.9  3.619535   -5.3 13.956136   -55.2 17.575671
Sat 2016.6110  -12.6  3.606984  -45.9 13.910256   -58.4 17.517240
Sun 2016.6137  +29.5  3.636514  +28.9 13.939110   +58.4 17.575624
Mon 2016.6164  -78.5  3.558010  +51.5 13.990590   -27.0 17.548600


The CAB declined -40k with Laptev (-15k) second.

Shadow NSIDC extent is now 5.5517 dropping  -71.6. CAB (-31k) and ESS (-20k) dropped most.

Like every day, an delta image is attached for a visual perspective.

Wipneus

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Re: 2016 sea ice area and extent data
« Reply #640 on: August 14, 2016, 05:30:11 PM »
Here is the shadow CT-area report based on calibrated F18 NSIDC sea ice concentration data:

day  CT-date       NH               SH                Global
Sat 2016.6110  -12.6  3.606984  -45.9 13.910256   -58.4 17.517240
Sun 2016.6137  +29.5  3.636514  +28.9 13.939110   +58.4 17.575624
Mon 2016.6164  -78.5  3.557990  +51.4 13.990507   -27.1 17.548497
Tue 2016.6192  +22.5  3.580469 +131.3 14.121842  +153.8 17.702311


CAB changed most and declined -20k.

Shadow NSIDC extent is 5.6220 an increase of +70.3k. Biggest uptick in the CAA (+35k) followed by Laptev (+17k).

Have a look at the attached delta map for the details.

Steven

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Re: 2016 sea ice area and extent data
« Reply #641 on: August 14, 2016, 09:04:21 PM »
Here is the shadow CT-area report based on calibrated F18 NSIDC sea ice concentration data:
...
2016.6192   ...   3.580469


That is the 5th lowest value on record for this date  (594k above 2012,  236k above 2007,  189k above 2011,  and 10k above 2015):



BornFromTheVoid

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Re: 2016 sea ice area and extent data
« Reply #642 on: August 15, 2016, 12:18:40 PM »
Update for the week to August 13th

The current 5 day trailing average is on 5,694,000km2 while the 1 day extent is at 5,622,000km2.

(All the following data is based on a trailing 5 day average)
The daily anomaly (compared to 81-10) is at -1,723,000km2, an increase from -1,659,000km2 last week. The anomaly compared to the 07, 11 and 12 average is at +229,000km2, an increase from +63,000km2 last week. We're currently 3rd lowest on record, the same as last week.



The average daily change over the last 7 days was -75.2k/day, compared to the long term average of -66.0k/day, and the 07, 11 and 12 average of -98.9k/day.
The average long term change over the next week is -53.7k/day, with the 07, 11, and 12 average being -70.1k/day.



The extent loss so far this August is the 6th largest on record. To achieve the largest monthly loss, a drop of at least 88.9k/day is required (requiring ~95.4k/day with with single day values), while the smallest loss requires a drop less than 3.7k/day (+0.03k/day with single day values) and an average loss requires a drop of 33.3k/day (~33.0k/day with single day values).


BornFromTheVoid

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Re: 2016 sea ice area and extent data
« Reply #643 on: August 15, 2016, 12:59:12 PM »


...Diff..... ......No of Years ......Percentage
Below........ ......26......... .......70.3%
0-100k..... ........1......... ........2.7%
100-250k..... .....0......... ........0.0%
250-500k..... .....1......... ........2.7%
500-1000k..... ...3......... ........8.1%
>1000k..... ...... 6......... ........16.2%

Wipneus

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Re: 2016 sea ice area and extent data
« Reply #644 on: August 15, 2016, 04:21:40 PM »
Here is the shadow CT-area report based on calibrated F18 NSIDC sea ice concentration data:

day  CT-date       NH               SH                Global
Sun 2016.6137  +29.5  3.636514  +28.9 13.939110   +58.4 17.575624
Mon 2016.6164  -78.5  3.557990  +51.4 13.990507   -27.1 17.548497
Tue 2016.6192  +23.1  3.581084 +131.4 14.121924  +154.5 17.703008
Wed 2016.6219  -76.7  3.504432 +105.5 14.227472   +28.9 17.731904


CAB and Laptev did it today: -71k and -32k. Kara increased by +17k.

Shadow NSIDC extent is now 5.4991 dropping -122.9k. All duw to a huge drop in Laptev: -110k. Kara in increased by +18k.

The delta map is attached as always.

Jim Pettit

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Re: 2016 sea ice area and extent data
« Reply #645 on: August 15, 2016, 04:54:14 PM »
Here is the shadow CT-area report based on calibrated F18 NSIDC sea ice concentration data:

day  CT-date       NH               SH                Global
Sun 2016.6137  +29.5  3.636514  +28.9 13.939110   +58.4 17.575624
Mon 2016.6164  -78.5  3.557990  +51.4 13.990507   -27.1 17.548497
Tue 2016.6192  +23.1  3.581084 +131.4 14.121924  +154.5 17.703008
Wed 2016.6219  -76.7  3.504432 +105.5 14.227472   +28.9 17.731904


Thanks. That puts 2016 at 9th place, surpassing 2013's September minimum, which moves into 10th. Next up: 8th place 2014, then 7th place 2009. Those two should be easy, as both are less than 80k away. But the BIG question is whether 2016 will be able to then reach and (possibly surpass) the tight cluster comprised of 2015, 2010, 2008, 2007, and 2011; all five are between 400k and 600k away.

2012 is, of course, far away with a lead of 1.27M.

BornFromTheVoid

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Re: 2016 sea ice area and extent data
« Reply #646 on: August 16, 2016, 05:06:55 PM »
Big drop on the NSIDC daily extent, -112k.

Single day extent is now less than 400k off the 2009, 2013 and 2014 minima.
5 day extent is less than 500k off the 2009 and 2013 minima, and just over 500k off the 2014 minimum.

Wipneus

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Re: 2016 sea ice area and extent data
« Reply #647 on: August 16, 2016, 05:18:36 PM »
Here is the shadow CT-area report based on calibrated F18 NSIDC sea ice concentration data:

day  CT-date       NH               SH                Global
Mon 2016.6164  -78.5  3.557990  +51.4 13.990507   -27.1 17.548497
Tue 2016.6192  +23.1  3.581084 +131.4 14.121924  +154.5 17.703008
Wed 2016.6219  -76.4  3.504732 +105.6 14.227520   +29.2 17.732252
Thu 2016.6247 -169.7  3.335018  +84.3 14.311798   -85.4 17.646816


Big losses in the CAB (-96k) and CAA (-49k).

Shadow NSIDC extent is now 5.3866 dropping -112.6k. Losses in CAA (-122k), ESS (-30k) and Kara (-17k). Laptev rebounded +79k.

The daily changes can be seen on the attached delta map.

Jim Pettit

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Re: 2016 sea ice area and extent data
« Reply #648 on: August 16, 2016, 05:51:56 PM »
Here is the shadow CT-area report based on calibrated F18 NSIDC sea ice concentration data:

day  CT-date       NH               SH                Global
Mon 2016.6164  -78.5  3.557990  +51.4 13.990507   -27.1 17.548497
Tue 2016.6192  +23.1  3.581084 +131.4 14.121924  +154.5 17.703008
Wed 2016.6219  -76.4  3.504732 +105.6 14.227520   +29.2 17.732252
Thu 2016.6247 -169.7  3.335018  +84.3 14.311798   -85.4 17.646816


SIA is now in 7th place. Additional SIA 2016 needs to lose in order to attain each of the remaining ranks:

6th: 2015: 242k
5th: 2010: 263k
4th: 2008: 332k
3rd: 2007: 416k
2nd: 2011: 431k
1st: 2012: 1102k

Darvince

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Re: 2016 sea ice area and extent data
« Reply #649 on: August 16, 2016, 08:04:00 PM »
All due to a huge drop in Laptev: -110k.
Losses in CAA (-122k),
Can you say flash melt much? :o