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James Lovejoy

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Re: 2015 sea ice area and extent data
« Reply #350 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.


jdallen

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Re: 2015 sea ice area and extent data
« Reply #351 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.
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anthropocene

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Re: 2015 sea ice area and extent data
« Reply #352 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.

Jim Pettit

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Re: 2015 sea ice area and extent data
« Reply #353 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.
« Last Edit: May 20, 2015, 01:34:08 PM by Jim Pettit »

Wipneus

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Re: 2015 sea ice area and extent data
« Reply #354 on: May 21, 2015, 07:09:07 AM »
Here is an update of the previous animation.

(still needs a click!)

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Re: 2015 sea ice area and extent data
« Reply #355 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)

Jim Hunt

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Re: 2015 sea ice area and extent data
« Reply #356 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.
« Last Edit: May 21, 2015, 05:19:16 PM by Jim Hunt »
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deep octopus

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Re: 2015 sea ice area and extent data
« Reply #357 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.

Jim Hunt

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Re: 2015 sea ice area and extent data
« Reply #358 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/

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!
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

BornFromTheVoid

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Re: 2015 sea ice area and extent data
« Reply #359 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/

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.
I recently joined the twitter thing, where I post more analysis, pics and animations: @Icy_Samuel

Jim Hunt

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Re: 2015 sea ice area and extent data
« Reply #360 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!
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

BornFromTheVoid

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Re: 2015 sea ice area and extent data
« Reply #361 on: May 21, 2015, 07:54:35 PM »
Ah, feckin' leap years. I'll stick with having a gap in my graphs!
I recently joined the twitter thing, where I post more analysis, pics and animations: @Icy_Samuel

Jim Hunt

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Re: 2015 sea ice area and extent data
« Reply #362 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.
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

Lord M Vader

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Re: 2015 sea ice area and extent data
« Reply #363 on: May 21, 2015, 08:53:12 PM »
Next year is a leap year... :P


Stephen

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Re: 2015 sea ice area and extent data
« Reply #364 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.  ;)
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Re: 2015 sea ice area and extent data
« Reply #365 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 :)

themgt

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Re: 2015 sea ice area and extent data
« Reply #366 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.

Wipneus

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Re: 2015 sea ice area and extent data
« Reply #367 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)

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Re: 2015 sea ice area and extent data
« Reply #368 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.

Wipneus

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Re: 2015 sea ice area and extent data
« Reply #369 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!

epiphyte

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Re: 2015 sea ice area and extent data
« Reply #370 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?




jdallen

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Re: 2015 sea ice area and extent data
« Reply #371 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.
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andy_t_roo

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Re: 2015 sea ice area and extent data
« Reply #372 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.

Wipneus

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Re: 2015 sea ice area and extent data
« Reply #373 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


BornFromTheVoid

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Re: 2015 sea ice area and extent data
« Reply #374 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.



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.



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.

I recently joined the twitter thing, where I post more analysis, pics and animations: @Icy_Samuel

Peter Ellis

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Re: 2015 sea ice area and extent data
« Reply #375 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.

epiphyte

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Re: 2015 sea ice area and extent data
« Reply #376 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.

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Re: 2015 sea ice area and extent data
« Reply #377 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)]
« Last Edit: May 25, 2015, 09:29:53 AM by Wipneus »

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Re: 2015 sea ice area and extent data
« Reply #378 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.

ktonine

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Re: 2015 sea ice area and extent data
« Reply #379 on: May 25, 2015, 08:56:32 AM »
Locating IMB Buoy 2015A on the AMSR2 map:



And 2015A gives this view:


Per 2015As datastream snowmelt began in the middle of May.

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Re: 2015 sea ice area and extent data
« Reply #380 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.

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Re: 2015 sea ice area and extent data
« Reply #381 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.

Jim Pettit

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Re: 2015 sea ice area and extent data
« Reply #382 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.

Wipneus

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Re: 2015 sea ice area and extent data
« Reply #383 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


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Re: 2015 sea ice area and extent data
« Reply #384 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.
I recently joined the twitter thing, where I post more analysis, pics and animations: @Icy_Samuel

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Re: 2015 sea ice area and extent data
« Reply #385 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.


Jim Pettit

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Re: 2015 sea ice area and extent data
« Reply #386 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:



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?

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Re: 2015 sea ice area and extent data
« Reply #387 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:



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.
This space for Rent.

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Re: 2015 sea ice area and extent data
« Reply #388 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.

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Re: 2015 sea ice area and extent data
« Reply #389 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.

Juan C. García

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Re: 2015 sea ice area and extent data
« Reply #390 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.

« Last Edit: May 30, 2015, 03:52:05 AM by Juan C. García »
Which is the best answer to Sep-2012 ASI lost (compared to 1979-2000)?
50% [NSIDC Extent] or
73% [PIOMAS Volume]

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

Jim Pettit

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Re: 2015 sea ice area and extent data
« Reply #391 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.

BornFromTheVoid

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Re: 2015 sea ice area and extent data
« Reply #392 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.



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.



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.

I recently joined the twitter thing, where I post more analysis, pics and animations: @Icy_Samuel

Wipneus

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Re: 2015 sea ice area and extent data
« Reply #393 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.


Wipneus

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Re: 2015 sea ice area and extent data
« Reply #394 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.

Jim Pettit

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Re: 2015 sea ice area and extent data
« Reply #395 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.

Wipneus

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Re: 2015 sea ice area and extent data
« Reply #396 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.

Wipneus

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Re: 2015 sea ice area and extent data
« Reply #397 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

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)

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Re: 2015 sea ice area and extent data
« Reply #398 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.

Stephen

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Re: 2015 sea ice area and extent data
« Reply #399 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 )
The ice was here, the ice was there,   
The ice was all around:
It crack'd and growl'd, and roar'd and howl'd,   
Like noises in a swound!
  Rime of the Ancient Mariner by Samuel Taylor Coleridge