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JimD

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Re: 2016 sea ice area and extent data
« Reply #550 on: July 20, 2016, 04:13:23 PM »
I envision this discussion in a dank dark tower in the middle ages.  Several monks from different monastery's are huddles around a table with BIG magnifying glasses and examining the head of a pin.  One is saying that angel is in a different place on the pin than last year and another is saying it is not.  The third monk is saying no you both are wrong that is the identical twin angel left over from the last leap year and it should have been removed and replaced with a regular angel.  Another monk is insisting that what is important is not where they are standing on the head of the pin but how many there are.  Being it is like ground hog day they go through this every year even though the difference in how many or what kind of angels are on the head of the pin from day to day has no relevance to speak of.   8)
We do not err because truth is difficult to see. It is visible at a glance. We err because this is more comfortable. Alexander Solzhenitsyn

How is it conceivable that all our technological progress - our very civilization - is like the axe in the hand of the pathological criminal? Albert Einstein

Neven

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Re: 2016 sea ice area and extent data
« Reply #551 on: July 20, 2016, 04:20:13 PM »
And on top of that, the pin is crooked!  ;)
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Dundee

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Re: 2016 sea ice area and extent data
« Reply #552 on: July 20, 2016, 04:42:00 PM »
Much worse than that - the old pin is broken, and we have to spend MONTHS proving to ourselves the new pin is just the same. Or it is not. Or it is, but only below 50ghz.

Dundee

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Re: 2016 sea ice area and extent data
« Reply #553 on: July 20, 2016, 05:32:57 PM »
On a more serious note, I am a beginner at this corner of analysis, but it took maybe thirty minutes to determine that leap year is a problem and a few days to determine that it is, more properly, a major pain in the rump (I am working with linear regressions day-wise, and they fall apart if the days do not match up).

Restating dates as fractional years is not bad, but pinning them to December 31st is. For my work, I've used whole number days, but pinned them to the date and time of the winter solstice. This leaves a dislocation when the equinox jumps between, say 1002 hours to 1359 hours (the former rounding to the previous day and the latter to the next) and it also leaves a leap day equivalent the day before the solstice. In practical terms, little is happening that time of the year ice-wise, and locking most of the year to the solar calendar improves the quality of regressions through the period of active analysis (at the cost of what ends up being 3-14 days of disturbed numbers in late December).

Below is a chart of the behavior of the summer solstice (shamelessly lifted from Wikipedia). By restating my data, I still have the underlying four year cycle, but have taken out the long term drift. As an aside, we have the Gregorian Calendar to thank for the fact there was no hundred year reset, which from today's perspective would have neatly divided the satellite record into nearly even halves.

I could use a precise annual fractional date (avoiding the rounding skip when the solstice jumps between morning and afternoon) but convinced myself there would be no point - this would add only false precision. The daily figures (from whatever source) are not based on a daily snapshot at 0000 or 1200 hours UT, but are rather based on whatever and whenever the satellite(s) served up throughout that day, based on their orbital mechanics and other conditions. To be anything like rigorous, you'd have to also regroup the orbit by orbit data streams to solar days rather than calendar days (and please, don't even talk about sidereal days - we - I'm pretty sure - don't care about them in this context, despite their role in orbital mechanics).

The real lesson to all of this is exactly as JimD stated above - if you are hanging on day to day numbers, be it daily changes or year to year comparisons, what is catching your eye is almost certainly more noise than signal. A good example is "do the peaks occur later (or earlier) now" - they may or may not, but unless all the underlying analysis effectively addresses the difference between the solar and calendar years, it is likely to misstate the picture, because any actual change is on a comparable scale to the equinox progression over the years of satellite record.
« Last Edit: July 20, 2016, 05:41:01 PM by Dundee »

Nick_Naylor

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Re: 2016 sea ice area and extent data
« Reply #554 on: July 20, 2016, 06:09:05 PM »
Even if you could synchronize the dates exactly, getting too hung up on daily values between years is giving too much credit to the noise vs. the signal.

Similarly, worrying about whether any particular measurement is a record vs. 2nd or 3rd place is human nature, but kind of superficial, especially when the other years are close to each other. Not that I'm immune to such silliness . . .  ::)

Wipneus

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Re: 2016 sea ice area and extent data
« Reply #555 on: July 20, 2016, 06:13:26 PM »
We're getting to the crux of the matter.

On July 18th and 19th Wipneus wrote this:

Quote
2016.5452 - 5.111185

But in the AreaCalculatedLikeCryosphereToday.txt data file it says (see attachment):

Quote
2016.5452 - 5.027240

So, what is it? I couldn't be more confused.

Ohh, that is obviously incorrect. I will let you know when fixed, checked and double checked.

Wipneus

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Re: 2016 sea ice area and extent data
« Reply #556 on: July 20, 2016, 06:22:45 PM »
In the mean time here is the report, with suspicious dates.

Here is the shadow CT-area report based on calibrated F18 NSIDC sea ice concentration data:

day  CT-date       NH               SH                Global
Tue 2016.5425  -91.8  5.240649   +5.7 12.867640   -86.2 18.108289
Wed 2016.5452 -129.8  5.110889  -20.5 12.847105  -150.3 17.957994
Thu 2016.5479  -83.8  5.027092  -14.1 12.833030   -97.9 17.860122
Fri 2016.5507   -7.4  5.019653  -68.8 12.764215   -76.3 17.783868

Only regional area increase worth mentioning is CAB: +24k.

Shadow NSIDC extent is 7.6691 dropping  -77.1k. ESS (-32k) and Hudson (-24k) dropped most. Baffin increased by +35k, contrast with UH AMSR2 results that indicated a large drop in that region.

As always, the delta map is there.

Neven

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Re: 2016 sea ice area and extent data
« Reply #557 on: July 20, 2016, 06:30:00 PM »
Ohh, that is obviously incorrect. I will let you know when fixed, checked and double checked.

Thanks for checking, Wipneus. I'm sorry the old CT-beast bites us yet again.

I think your file is correct, as the date for the 2016 values correspond with those of previous years. So maybe you jumped a date when reporting here. That's usually how my spreadsheet gets screwed up (not entering one value and then just trudging on).
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Wipneus

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Re: 2016 sea ice area and extent data
« Reply #558 on: July 21, 2016, 04:32:56 PM »
Here is the shadow CT-area report based on calibrated F18 NSIDC sea ice concentration data:

day  CT-date       NH               SH                Global
Wed 2016.5452 -129.8  5.110889  -20.5 12.847105  -150.3 17.957994
Thu 2016.5479  -83.8  5.027092  -14.1 12.833030   -97.9 17.860122
Fri 2016.5507   -7.2  5.019887  -68.6 12.764399   -75.8 17.784286
Sat 2016.5534  -79.7  4.940148 +123.2 12.887570   +43.4 17.827718


With biggest regional area declines in the CAB (-32k) and CAA (-23k).

Shadow NSIDC extent is now 7.5276 dropping -141.5k. Biggest declines in ESS (-37k), CAA (-33k), Baffin (-27k) and Kara (-25k). Greenland Sea provided the uptick (+19k).

Concluding as ever with the attached daily delta map.


Jim Pettit

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Re: 2016 sea ice area and extent data
« Reply #559 on: July 21, 2016, 04:47:39 PM »
FWIW, as of tomorrow, 2016 SIA will be lower than the annual minimums recorded in the following years:

1979-1983
1985-1988
1992
1996

BornFromTheVoid

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Re: 2016 sea ice area and extent data
« Reply #560 on: July 21, 2016, 05:27:35 PM »
Despite the big extent drops in the last 2 days, both the single day and now 5 day NSIDC extent are up to 4th lowest on record.

With the 5 day average, we are now approaching the minimum value set in 1980. Another 3-4 days and we should drop the 179k required.

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

BornFromTheVoid

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Re: 2016 sea ice area and extent data
« Reply #561 on: July 22, 2016, 04:47:01 PM »
A relatively small drop today of 63k on the NSIDC extent. Still 4th lowest, and now just 40k below 2013.
I recently joined the twitter thing, where I post more analysis, pics and animations: @Icy_Samuel

Wipneus

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Re: 2016 sea ice area and extent data
« Reply #562 on: July 22, 2016, 06:03:58 PM »
Here is the shadow CT-area report based on calibrated F18 NSIDC sea ice concentration data:

day  CT-date       NH               SH                Global
Thu 2016.5479  -83.8  5.027092  -14.1 12.833030   -97.9 17.860122
Fri 2016.5507   -7.2  5.019887  -68.6 12.764399   -75.8 17.784286
Sat 2016.5534  -79.8  4.940048 +123.2 12.887609   +43.4 17.827657
Sun 2016.5562 -136.3  4.803748  +27.8 12.915445  -108.5 17.719193


Regional CAB dropped most(-56k), with ESS (-19k) second.

Shadow NSIDC extent is now 7.4648 dropping  -62.8k. Baffin dropped -33k, ESS -18k.

The daily delta map is attached as usual.

Wipneus

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Re: 2016 sea ice area and extent data
« Reply #563 on: July 23, 2016, 05:46:22 PM »
Here is the shadow CT-area report based on calibrated F18 NSIDC sea ice concentration data:
day  CT-date       NH               SH                Global
Fri 2016.5507   -7.2  5.019887  -68.6 12.764399   -75.8 17.784286
Sat 2016.5534  -79.8  4.940048 +123.2 12.887609   +43.4 17.827657
Sun 2016.5562 -136.3  4.803723  +27.8 12.915419  -108.5 17.719142
Mon 2016.5589  -42.2  4.761475 +115.7 13.031137   +73.5 17.792612


Laptev shows the biggest drop (-37k), while CAB increases by +25k.

Shadow NSIDC extent is now 7.3859  dropping -79.0k. Most of that is in the Beaufort (-37k), ESS is second with -19k.

The delta map is attached as always.

BornFromTheVoid

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Re: 2016 sea ice area and extent data
« Reply #564 on: July 24, 2016, 04:11:59 PM »
Update for the week to July 23rd

The current 5 day trailing average is on 7,468,000km2 while the 1 day extent is at 7,293,000km2.

(All the following data is based on a trailing 5 day average)
The daily anomaly (compared to 81-10) is at -1,569,000km2, a decrease from -1,760,000km2 last week. The anomaly compared to the 07, 11 and 12 average is at +198,000km2, an increase from +33,000km2 last week. We're currently 4th lowest on record, down from 3rd last week.



The average daily change over the last 7 days was -62.0k/day, compared to the long term average of -89.4k/day, and the 07, 11 and 12 average of -85.6k/day.
The average long term change over the next week is -86.1k/day, with the 07, 11, and 12 average being -81.5k/day.



The extent loss so far this July is the 17th smallest on record. To achieve the largest monthly loss, a drop of at least 188.9k/day is required (requiring ~222.6k/day with with single day values), while the smallest loss requires a drop of less than 0.6k/day (~28.4k/day increase with single day values) and an average loss requires a drop of 73.0k/day (~81.5k/day with single day values).

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

BornFromTheVoid

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Re: 2016 sea ice area and extent data
« Reply #565 on: July 24, 2016, 04:17:05 PM »
The 5 day average NSIDC extent has dropped below the first previous minimum set in 1980. We're now also within 500k of 6 other years, 1982, 83, 86, 88, 92 and 96.

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

Wipneus

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Re: 2016 sea ice area and extent data
« Reply #566 on: July 24, 2016, 05:51:13 PM »
Here is the shadow CT-area report based on calibrated F18 NSIDC sea ice concentration data:

day  CT-date       NH               SH                Global
Sat 2016.5534  -79.8  4.940048 +123.2 12.887609   +43.4 17.827657
Sun 2016.5562 -136.3  4.803723  +27.8 12.915419  -108.5 17.719142
Mon 2016.5589  -42.1  4.761607 +115.6 13.030979   +73.4 17.792586
Tue 2016.5616   -9.6  4.751969 +137.0 13.168003  +127.4 17.919972



Very quiet regionally, CAB changed most an increase of +16k.

Shadow NSIDC extent is 7.2931 dropping -92.8k. ESS dropped -48k, Hudson -20k. Kara increased +19k.

Today┬┤s delta map is attached .

[EDIT: fixed the NSIDC extent value, thanks BFTV]
« Last Edit: July 24, 2016, 06:42:45 PM by Wipneus »

Steven

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Re: 2016 sea ice area and extent data
« Reply #567 on: July 24, 2016, 07:34:54 PM »
Here is the shadow CT-area report based on calibrated F18 NSIDC sea ice concentration data:

2016.5616   ... 4.751969

Now in 4th place.

Date                  CT-area
2012.5616        4.425 million km2
2011.5616        4.554
2007.5616        4.680
2016.5616      4.752
2013.5616        4.864
       ...                  ...


Jim Pettit

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Re: 2016 sea ice area and extent data
« Reply #568 on: July 25, 2016, 12:35:29 PM »
ADS-NIPR Extent:
6,990,510 km2 (24 July)
Down 6,951,997 km2 (49.86%) from 2016 maximum of 13,942,507 km2 on 29 February.
3,813,055 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Down 77,463 km2 (-1.1%) from previous day.
Down 464,446 km2  (-6.23%) over past seven days (daily average: -66,349 km2).
Down 1,983,198 km2  (-16.21%) for July (daily average: -82,633 km2).
887,147 km2 below 2000s average for this date.
20,029 km2 below 2010s average for this date.
126,567 km2 below 2015 value for this date.
280,016 km2 above 2012 value for this date.
1st lowest year-to-date (01 January - 24 July) average.
1st lowest July to-date average.
4th lowest value for the date.
128 days this year (62.44% year-to-date) have recorded the lowest daily extent.
35 days (17.07%) have recorded the second lowest.
24 days (11.71%) have recorded the third lowest.
187 days in total (91.22%) have been among the lowest three on record.


CT Area:
4,751,969 km2 (25 July [Day 0.5616])
Down 8,169,389 km2 (63.22%) from 2016 maximum of 12,921,358 km2 on 29 March [Day 0.2384].
2,517,960 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Down 9,638 km2 (-.2%) from previous day.
Down 488,680 km2 (-9.56%) over past seven days (daily average: -69,811 km2).
Down 2,342,299 km2 (-21.03%) for July (daily average: -93,692 km2).
801,202 km2 below 2000s average for this date.
79,029 km2 below 2010s average for this date.
190,334 km2 below 2015 value for this date.
326,777 km2 above 2012 value for this date.
4th lowest value for the 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 #569 on: July 25, 2016, 04:43:07 PM »
Here is the shadow CT-area report based on calibrated F18 NSIDC sea ice concentration data:

day  CT-date       NH               SH                Global
Sun 2016.5562 -136.3  4.803723  +27.8 12.915419  -108.5 17.719142
Mon 2016.5589  -42.1  4.761607 +115.6 13.030979   +73.4 17.792586
Tue 2016.5616   -9.8  4.751839 +137.0 13.167949  +127.2 17.919788
Wed 2016.5644  -84.5  4.667375  +81.5 13.249405    -3.0 17.916780


ESS again dropped most :-35k.

NSIDC extent is now 7.2554 down -37.6k. ESS (again) dropped most: -30k.

The daily delta map is attached as expected.

BornFromTheVoid

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Re: 2016 sea ice area and extent data
« Reply #570 on: July 25, 2016, 04:45:55 PM »
Latest situation with regard to previous NSIDC extent minima (using the 5 day average)



Diff...........No of Years.....Percentage
Below 0..........1................3%
0-100k...........0................0%
100-250k........5...............14%
250-500k........6...............16%
500-1000k......4................11%
>1000k.........21...............57%
I recently joined the twitter thing, where I post more analysis, pics and animations: @Icy_Samuel

Wipneus

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Re: 2016 sea ice area and extent data
« Reply #571 on: July 26, 2016, 05:15:58 PM »
Here is the shadow CT-area report based on calibrated F18 NSIDC sea ice concentration data:

day  CT-date       NH               SH                Global
Mon 2016.5589  -42.1  4.761607 +115.6 13.030979   +73.4 17.792586
Tue 2016.5616   -9.8  4.751839 +137.0 13.167949  +127.2 17.919788
Wed 2016.5644  -84.3  4.667566  +81.4 13.249363    -2.9 17.916929
Thu 2016.5671  -46.3  4.621297   +7.4 13.256752   -38.9 17.878049


Regionally ESS continues to decline (-24k), Hudson -15k while the CAB increased by +19k.

Shadow NSIDC extent is now 7.2033 dropping -52.2k. Hudson sold for -23k less, Beaufort -19k and Kara -15k.

Concludes with the attached delta map.

Wipneus

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Re: 2016 sea ice area and extent data
« Reply #572 on: July 27, 2016, 04:52:41 PM »
Here is the shadow CT-area report based on calibrated F18 NSIDC sea ice concentration data:

day  CT-date       NH               SH                Global
Tue 2016.5616   -9.8  4.751839 +137.0 13.167949  +127.2 17.919788
Wed 2016.5644  -84.3  4.667566  +81.4 13.249363    -2.9 17.916929
Thu 2016.5671  -46.3  4.621301   +7.4 13.256794   -38.8 17.878095
Fri 2016.5699  -53.0  4.568267  +54.4 13.311227    +1.4 17.879494


No big regional changes, except the CAB: -34k.

Shadow NSIDC extent is 7.1714 dropping  -31.9k. Baffin coughed up -31k, Laptev was second at -19k.

The daily delta map is attached as always.

epiphyte

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Re: 2016 sea ice area and extent data
« Reply #573 on: July 27, 2016, 06:28:06 PM »
Wow. Looks like they woke up in Sandusky Ohio this morning not only hot and bothered in the 90s, but also unexpectedly icebound!

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Re: 2016 sea ice area and extent data
« Reply #574 on: July 28, 2016, 06:14:32 PM »
Here is the shadow CT-area report based on calibrated F18 NSIDC sea ice concentration data:

day  CT-date       NH               SH                Global
Wed 2016.5644  -84.3  4.667566  +81.4 13.249363    -2.9 17.916929
Thu 2016.5671  -46.3  4.621301   +7.4 13.256794   -38.8 17.878095
Fri 2016.5699  -52.9  4.568436  +54.4 13.311186    +1.5 17.879622
Sat 2016.5726  -64.4  4.504044  -52.5 13.258720  -116.9 17.762764


Like yesterday is is only the CAB that is moving: -41k this time.

Shadow NSIDC extent is now 7.1386 dropping -32.8k. Kara had an uptick of +23k. Other regions were slow, Beaufort most with -13k.

The daily delta map is where you can expect it.

jdallen

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Re: 2016 sea ice area and extent data
« Reply #575 on: July 28, 2016, 10:07:44 PM »
Here is the shadow CT-area report based on calibrated F18 NSIDC sea ice concentration data:

day  CT-date       NH               SH                Global
Wed 2016.5644  -84.3  4.667566  +81.4 13.249363    -2.9 17.916929
Thu 2016.5671  -46.3  4.621301   +7.4 13.256794   -38.8 17.878095
Fri 2016.5699  -52.9  4.568436  +54.4 13.311186    +1.5 17.879622
Sat 2016.5726  -64.4  4.504044  -52.5 13.258720  -116.9 17.762764


Like yesterday is is only the CAB that is moving: -41k this time.

Shadow NSIDC extent is now 7.1386 dropping -32.8k. Kara had an uptick of +23k. Other regions were slow, Beaufort most with -13k.

The daily delta map is where you can expect it.
<snippage> moved to a better thread for the discussion.
This space for Rent.

Jim Pettit

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Re: 2016 sea ice area and extent data
« Reply #576 on: July 29, 2016, 12:52:34 PM »
Here is the shadow CT-area report based on calibrated F18 NSIDC sea ice concentration data:

day  CT-date       NH               SH                Global
Wed 2016.5644  -84.3  4.667566  +81.4 13.249363    -2.9 17.916929
Thu 2016.5671  -46.3  4.621301   +7.4 13.256794   -38.8 17.878095
Fri 2016.5699  -52.9  4.568436  +54.4 13.311186    +1.5 17.879622
Sat 2016.5726  -64.4  4.504044  -52.5 13.258720  -116.9 17.762764



2016 has one more day to gain ground on 2012, with the latter losing just 1k of area on 0.5753. Then the GAC kicked in that year, stripping away more than a million square kilometers of ice over a 10-day period. It's highly doubtful we'll see any such thing this year, and because of that, it's looking more and more as though 2016 will bottom out between 3.4M and 3.6M --that is, somewhere around or just above the average of the last ten years.

FWIW, 2016 SIA is now lower than the annual minima recorded from 1979-1990, 1992, 1994, 1996-1997, and 2001.

BornFromTheVoid

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Re: 2016 sea ice area and extent data
« Reply #577 on: July 29, 2016, 03:56:32 PM »
Huge drop on the single day NSIDC extent, down 230k, but still 4th lowest on record.

Using the 5 day trailing average, we have now dropped below the minima of 6 of the 37 previous years.



Below are the stats with regard to all previous minima and current 5 day extent.

Diff..........No of Years.....Percentage
Below 0..........6...............16.2%
0-100k...........1.................2.7%
100-250k........5...............13.5%
250-500k........0.................0.0%
500-1000k......7................18.9%
>1000k.........18................48.6%
I recently joined the twitter thing, where I post more analysis, pics and animations: @Icy_Samuel

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Re: 2016 sea ice area and extent data
« Reply #578 on: July 29, 2016, 04:18:14 PM »
Here is the shadow CT-area report based on calibrated F18 NSIDC sea ice concentration data:

day  CT-date       NH               SH                Global
Thu 2016.5671  -46.3  4.621301   +7.4 13.256794   -38.8 17.878095
Fri 2016.5699  -52.9  4.568436  +54.4 13.311186    +1.5 17.879622
Sat 2016.5726  -64.8  4.503638  -52.6 13.258609  -117.4 17.762247
Sun 2016.5753 -182.0  4.321657 +157.2 13.415760   -24.8 17.737417



A century for area of the CAB: -112k, Beaufort second (-31k) and even CAA worth mentioning (-19k).

Shadow NSIDC extent is now 6.9094 dropping -229.2k. Many regions did their best: Beaufort (-84k), Kara (-33k), CAA (-27k), Laptev (-21k) and ESS (-20k).

Today's delta map is filled with reds and pinks.
« Last Edit: July 29, 2016, 04:42:00 PM by Wipneus »

Shared Humanity

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Re: 2016 sea ice area and extent data
« Reply #579 on: July 29, 2016, 10:42:46 PM »
What worries me are the blue areas along the Atlantic side. The ice is beginning to migrate towards the Barents. It won't last long as it moves into these very warm waters.

Jim Pettit

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Re: 2016 sea ice area and extent data
« Reply #580 on: July 30, 2016, 02:28:09 PM »
ADS-NIPR Extent:
6,622,391 km2 (29 July)
Down 7,320,116 km2 (52.5%) from 2016 maximum of 13,942,507 km2 on 29 February.
3,444,936 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Down 62,949 km2 (-.94%) from previous day.
Down 505,285 km2  (-7.09%) over past seven days (daily average: -72,184 km2).
Down 2,351,317 km2  (-19.22%) for July (daily average: -81,080 km2).
848,518 km2 below 2000s average for this date.
20,395 km2 below 2010s average for this date.
107,661 km2 below 2015 value for this date.
419,358 km2 above 2012 value for this date.
Lowest year-to-date (01 January - 29 July) average.
3rd lowest July to-date average.
4th lowest value for the date.
128 days this year (60.95% year-to-date) have recorded the lowest daily extent.
35 days (16.67%) have recorded the second lowest.
24 days (11.43%) have recorded the third lowest.
187 days in total (89.05%) have been among the lowest three on record.


CT Area:
4,321,657 km2 (30 July [Day 0.5753])
Down 8,599,701 km2 (66.55%) from 2016 maximum of 12,921,358 km2 on 29 March [Day 0.2384].
2,087,648 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Down 181,981 km2 (-4.04%) from previous day.
Down 482,066 km2 (-10.12%) over past seven days (daily average: -68,867 km2).
Down 2,772,611 km2 (-24.89%) for July (daily average: -92,420 km2).
965,307 km2 below 2000s average for this date.
238,082 km2 below 2010s average for this date.
210,109 km2 below 2015 value for this date.
85,790 km2 above 2012 value for this date.
3rd lowest value for the 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 #581 on: July 30, 2016, 04:43:52 PM »

day  CT-date       NH               SH                Global
Fri 2016.5699  -52.9  4.568436  +54.4 13.311186    +1.5 17.879622
Sat 2016.5726  -64.8  4.503638  -52.6 13.258609  -117.4 17.762247
Sun 2016.5753 -182.3  4.321316 +157.4 13.415964   -25.0 17.737280
Mon 2016.5781  -40.7  4.280588 +156.8 13.572807  +116.1 17.853395



Again it the CAB at its own that does the lifting: -45k.

Shadow NSIDC extent is 6.9211 an increase of +11.7k. Little changes regionally, Hudson most with +13k.

The delta map is attached as always.

Wipneus

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Re: 2016 sea ice area and extent data
« Reply #582 on: July 31, 2016, 04:20:35 PM »
Here is the shadow CT-area report based on calibrated F18 NSIDC sea ice concentration data:

day  CT-date       NH               SH                Global
Sat 2016.5726  -64.8  4.503638  -52.6 13.258609  -117.4 17.762247
Sun 2016.5753 -182.3  4.321316 +157.4 13.415964   -25.0 17.737280
Mon 2016.5781  -40.1  4.281226 +156.9 13.572847  +116.8 17.854073
Tue 2016.5808 -143.9  4.137335 +187.0 13.759852   +43.1 17.897187



Something big just dropped: Laptev (-67k) , CAB (-49k) and CAA (-23k).

Shadow NSIDC extent is now 6.7194 dropping a big -201.7. It is not the first of the month (that won't be for two days) but Laptev -135k. CAA (-38k) and CAB (-19k) follow behind. Beaufort recovers with a +25k uptick.

The attached delta map shows the damage done.

BornFromTheVoid

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Re: 2016 sea ice area and extent data
« Reply #583 on: July 31, 2016, 04:38:28 PM »
Update for the week to July 30th

The current 5 day trailing average is on 6,972,000km2 while the 1 day extent is at 6,719,000km2.

(All the following data is based on a trailing 5 day average)
The daily anomaly (compared to 81-10) is at -1,462,000km2, a decrease from -1,569,000km2 last week. The anomaly compared to the 07, 11 and 12 average is at +272,000km2, an increase from +198,000km2 last week. We're currently 4th lowest on record, same as last week.



The average daily change over the last 7 days was -70.9k/day, compared to the long term average of -86.1k/day, and the 07, 11 and 12 average of -81.5k/day.
The average long term change over the next week is -79.4k/day, with the 07, 11, and 12 average being -77.5k/day.



The extent loss so far this July is the 17th smallest on record. To achieve the largest monthly loss, a drop of at least 1,019.4k/day is required (requiring ~4,619k/day with with single day values), while the smallest loss requires an increase of at least 491.4k/day (~2,199k/dayincrease with single day values) and an average loss requires a drop of 164.0k/day (~369k/day with single day values).

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

BornFromTheVoid

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Re: 2016 sea ice area and extent data
« Reply #584 on: July 31, 2016, 04:50:10 PM »
Using the 5 day average, we've now dropped below 7/37 previous minima, and we're within 500k of another 12.



Some stats on the difference between current extent and previous minima

Diff.............No of Years....Percentage
Below 0.............7.............18.9%
0-100k..............5.............13.5%
100-250k...........0.............0.0%
250-500k...........3.............8.1%
500-1000k.........8.............21.6%
>1000k.............14............37.8%
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Re: 2016 sea ice area and extent data
« Reply #585 on: July 31, 2016, 05:29:49 PM »
Wipneus's "shadow" area numbers show that 2016 SIA has dropped below the annual minima recorded in every year prior to 2004, with the exception of 2002. Three more years should be beaten in the next few days--2002, 2005, and 2006--and then there's a substantial gap before the next years is past (2013).

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Re: 2016 sea ice area and extent data
« Reply #586 on: July 31, 2016, 08:04:37 PM »
Here is the shadow CT-area report based on calibrated F18 NSIDC sea ice concentration data:

2016.5808  ...  4.137335

Currently 2nd lowest (behind 2012):


Michael Hauber

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Re: 2016 sea ice area and extent data
« Reply #587 on: August 01, 2016, 06:19:35 AM »
ADS daily change:  -96228
Climate change:  Prepare for the worst, hope for the best, expect the middle.

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Re: 2016 sea ice area and extent data
« Reply #588 on: August 01, 2016, 10:17:14 AM »
Back in second place huh ?
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Let's not waste either.

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Re: 2016 sea ice area and extent data
« Reply #589 on: August 01, 2016, 02:51:38 PM »
Here is the shadow CT-area report based on calibrated F18 NSIDC sea ice concentration data:

2016.5808  ...  4.137335

Currently 2nd lowest (behind 2012):



With SIA 2nd lowest and SIE not dropping as quickly, the ice is spread out more than in years past. This can't be good news for the remainder of the melt season.

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Re: 2016 sea ice area and extent data
« Reply #590 on: August 01, 2016, 03:05:16 PM »
This is why I'm now seeing the late winter Fragmentation events as a new direction as the basin moves toward a seasonal routine? 3 year old ice has been through 3 cycles with old fracture line criss crossing newer ones. Warm water/weather does for the 'glue' holding floes together and leaves us with floes so small the heat enters through top, base and sides.

We are left seeing similar levels of energy doing far more damage to the ice volume than in past years?

I'm still thinking we might go low but it will be the last couple of weeks of melt season that will reveal this as large ares of fragmented ice, that would have survived other seasons due to being part of big floes, blink out?

In the future I imagine we could look at any sized floe and know how much energy will be needed to see it melt? Such calcs have to involve it's fragmentation potential though?

As it is the 'leftover ice' will be so thin that , by winters end, we will still be seeing floes in the range of FY ice? That will mean plenty of break ups over the winter and just exacerbate next seasons woes........... and remember next year is the earliest possible return of the perfect melt storm synoptic ( we'll know pretty quickly if it isn't!)
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Bill Fothergill

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Re: 2016 sea ice area and extent data
« Reply #591 on: August 01, 2016, 03:25:51 PM »
...
leaves us with floes so small the heat enters through top, base and sides.
...


Exactly. Consider the hypothetical case of a cube of ice that is (say) one metre along each edge. The volume would obviously be one cubic metre, and its surface area would be 6 sq metres.

Now imagine if this was somehow fractured into 8 identical smaller cubes, such that each edge was only 0.5 metres. The volume would be unchanged, but the total surface area would double to 12 sq metres. With uneven fracturing, the ratio between surface area and volume would rise much faster.

As the rate of energy transfer into the ice is a function of surface area...   Well, I don't think it needs to be spelled out.

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Re: 2016 sea ice area and extent data
« Reply #592 on: August 01, 2016, 04:09:20 PM »
ADS daily change:  -96228

In the latest ASI update I wrote: If it now somehow manages to end the month between 2011 and 2015, there's still room for August weather to keep the race exciting.

Well, JAXA SIE managed to do just that:
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Re: 2016 sea ice area and extent data
« Reply #593 on: August 01, 2016, 04:52:33 PM »
Here is the shadow CT-area report based on calibrated F18 NSIDC sea ice concentration data:

day  CT-date       NH               SH                Global
Sun 2016.5753 -182.3  4.321316 +157.4 13.415964   -25.0 17.737280
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  -97.3  4.039888 -115.2 13.644908  -212.5 17.684796


Three regions: ESS (-27k), CAA (-26k) and CAB (-20k) are the main contributors.

Shadow NSIDC extent is now 6.6645 dropping  -54.8k. Laptev had a big rebound: +74k, as long as there is a lot of ice hoovering around 15% concentration such swings can be expected. There are also big declines: CAA (-55k), ESS (-33k) , Hudson (-24k) and CAB (-18k).

The delta map has a colorful way of telling the story.

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Re: 2016 sea ice area and extent data
« Reply #594 on: August 01, 2016, 05:33:02 PM »
...
leaves us with floes so small the heat enters through top, base and sides.
...


Exactly. Consider the hypothetical case of a cube of ice that is (say) one metre along each edge. The volume would obviously be one cubic metre, and its surface area would be 6 sq metres.

Now imagine if this was somehow fractured into 8 identical smaller cubes, such that each edge was only 0.5 metres. The volume would be unchanged, but the total surface area would double to 12 sq metres. With uneven fracturing, the ratio between surface area and volume would rise much faster.

As the rate of energy transfer into the ice is a function of surface area...   Well, I don't think it needs to be spelled out.
For what it's worth, side melt doesn't contribute significantly until your floe size gets under 150M or so in diameter.
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Re: 2016 sea ice area and extent data
« Reply #595 on: August 02, 2016, 01:10:34 AM »

For what it's worth, side melt doesn't contribute significantly until your floe size gets under 150M or so in diameter.

I actually think the floe fracturing needs to take place on a considerably smaller scale than 150 metres for the effect I was describing to become manifest. (In my very hypothetical example, I started with a unit cube.)

The total surface area of circular floe with a diameter of 150 metres and a thickness of 1 metre would be just under 36 thousand sq metres. The effect of a full-depth vertical fracture line running edge-to-edge straight through the centre would only increase the total surface area by a little under 1%.

However, a similar fracture through a second circular floe of the same thickness, but with a 15 metre diameter would result in a ~7% overall increase in surface area. For a 5 metre diameter floe, the increase rises to 18%. It is when the horizontal scale approaches the thickness scale that the effect really kicks into gear.

When we get real "slushy" ice, the scaling should be such that surface area increase becomes a significant contributory factor to the enthalpy increase of the ice mass.

For floes where the areal dimensions are still significantly larger than the thickness, I would expect effects such as abrasion along fractures to greatly outweigh side melt.

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Re: 2016 sea ice area and extent data
« Reply #596 on: August 02, 2016, 02:55:51 AM »
This study claimed that without the GAC 2012 minimum would have been only 150k higher.  The PIOMAS model for no GAC falls about 450k behind in late August, but catches up again to only be 150k behind at minimum.  I think in part the GAC just sped up the melting of the vulnerable ice that was doomed to melt anyway.  And in part the melting was sped up by mixing, at the cost of reduced ocean heat available for later in the season.

It is interesting to look at what that study considers the 'no GAC' case.  They take the same weather conditions during the GAC but halve the wind speeds.  So cool and cloudy, but without the severe winds.  Presumably if the GAC was replaced by warmer and sunnier conditions similar to what is currently forecast than the minimum for the No GAC case  in 2012 would have been reduced further, perhaps beyond what occurred with the GAC.
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Re: 2016 sea ice area and extent data
« Reply #597 on: August 02, 2016, 09:24:10 AM »
Quote
This study claimed that without the GAC 2012 minimum would have been only 150k higher.

That is consistent with my findings  :



based on June data, 2012 was pre-conditioned with low land snow cover and low ice concentration and low ice "area" which collaborated to produce a record low extent.
The GAC 2012 was just adding the proverbial frosting on the cake that year.
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Re: 2016 sea ice area and extent data
« Reply #598 on: August 02, 2016, 12:23:19 PM »
ADS-NIPR Extent:
6,321,835 km2 (01 August)
Down 7,620,672 km2 (54.66%) from 2016 maximum of 13,942,507 km2 on 29 February.
3,144,380 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Down 116,275 km2 (-1.81%) from previous day.
Down 590,452 km2  (-8.54%) over past seven days (daily average: -84,350 km2).
Down 116,275 km2  (-.95%) for August (daily average: -116,275 km2).
885,576 km2 below 2000s average for this date.
137,399 km2 below 2010s average for this date.
146,308 km2 below 2015 value for this date.
239,435 km2 above 2012 value for this date.
Lowest year-to-date (01 January - 01 August) average.
4th lowest August to-date average.
4th lowest value for the date.
128 days this year (60.09% year-to-date) have recorded the lowest daily extent.
35 days (16.43%) have recorded the second lowest.
24 days (11.27%) have recorded the third lowest.
187 days in total (87.79%) have been among the lowest three on record.


CT Area:
4,039,888 km2 (02 August [Day 0.5836])
Down 8,881,470 km2 (68.73%) from 2016 maximum of 12,921,358 km2 on 29 March [Day 0.2384].
1,805,879 km2 above record minimum area of 2,234,010 km2 (14 September 2012).
Down 97,276 km2 (-2.35%) from previous day.
Down 627,678 km2 (-13.58%) over past seven days (daily average: -89,668 km2).
Down 241,338 km2 (-2.17%) for August (daily average: -120,669 km2).
1,025,733 km2 below 2000s average for this date.
290,693 km2 below 2010s average for this date.
206,603 km2 below 2015 value for this date.
252,692 km2 above 2012 value for this date.
2nd lowest value for the 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 substituted in if/when available. In the meantime, thanks, Wipneus!

Wipneus

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Re: 2016 sea ice area and extent data
« Reply #599 on: August 02, 2016, 04:15:40 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


Very little (less than 10k) of this can be attributed to the first of the month effect. Most of the decline was in the CAB: -46k.

Shadow NSIDC extent was 6.5017 dropping -162.9k. At most -25k can be caused by the new monthly ice mask (aka first of the month effect). Many regions can be mentioned Laptev (-32k), Chukchi (-29k), Beaufort (-24k), Hudson (-20k) and CAB (-19k).

As always, the attached delta map shows the numbers graphically.