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Author Topic: 2017 sea ice area and extent data  (Read 92295 times)

DrTskoul

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Re: 2017 sea ice area and extent data
« Reply #50 on: January 16, 2017, 08:30:59 PM »
Thanks Jim.... Fascinating  :o
« Last Edit: January 16, 2017, 10:07:01 PM by DrTskoul »
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Gray-Wolf

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Re: 2017 sea ice area and extent data
« Reply #51 on: January 16, 2017, 09:05:21 PM »
The only reason 2012 saw that late surge was the 'ice factory' setting up over the Bering Straights. None of that 'extension' was 'good ice' as it all fell ourside the basin and so drove the rapid collapse we saw in early season (not that this stopped the usual suspects crying 'recovery/record' as though meaningful?).

The real action from now until melt season is the thickening and 'conditioning' of the ice prior to melt season. This storm may well bring a halt , basin wide, to this activity?

It is the same as the 2014 and 2015 extension to the Antarctic sea ice which , to anyone caring to notice, was an early brake up/float off of the peripheral pack at freezing seasons end. Take that 'growth spurt' away and you see a melt season beginning just as 2016 has done ( but to more raised eyebrows ) now the Pacific drivers now demand such.
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Wipneus

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Re: 2017 sea ice area and extent data
« Reply #52 on: January 19, 2017, 06:53:44 PM »
Cross post from the not-so-stupid-questions thread:

Are the NSIDC links moved are just experiencing tech problems?


They have moved , with some other changes as well:

https://nsidc.org/the-drift/data-update/sea-ice-index-ftp-directory-structure-changing/

On 31 Jan the ftp will be closed and all that data can only be accessed from the protected (user+password, free registration) https connection. Start here and find the rest:

https://daacdata.apps.nsidc.org/pub/DATASETS/NOAA/G02135/

etcetera.

Pmt111500

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Re: 2017 sea ice area and extent data
« Reply #53 on: January 20, 2017, 03:17:03 AM »
(public notification) Please someone take a copy of the ftp-file and check it line by line (including non-written characters) against the passworded file afterwards. Not sure if this would be good to do via entirely new machinery. New email address could be used, or if you trust the future government sign up with your current address using your bank account details as password. Remember, if you've got nothing to hide, you got nothing to be afraid. (/mistrust of denialists)
« Last Edit: January 20, 2017, 03:27:26 AM by Pmt111500 »
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epiphyte

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Re: 2017 sea ice area and extent data
« Reply #54 on: January 20, 2017, 04:00:33 PM »
Remember, if you've got nothing to hide, you got nothing to be afraid.

When people say this to me I always ask to go through their wallet. It usually ends the argument right there!

magnamentis

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Re: 2017 sea ice area and extent data
« Reply #55 on: January 20, 2017, 04:11:13 PM »
Remember, if you've got nothing to hide, you got nothing to be afraid.

When people say this to me I always ask to go through their wallet. It usually ends the argument right there!

good idea indeed, will remember that one because that saying drives me mad. it's the same people who even hide their belly button LOL. another idea would be to ask them to visit a nudist beach.
END [OT] just coudn't resist

cheers
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Tealight

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Re: 2017 sea ice area and extent data
« Reply #56 on: January 20, 2017, 07:34:05 PM »
Are the NSIDC links moved are just experiencing tech problems?


They have moved , with some other changes as well:

https://nsidc.org/the-drift/data-update/sea-ice-index-ftp-directory-structure-changing/

On 31 Jan the ftp will be closed and all that data can only be accessed from the protected (user+password, free registration) https connection. Start here and find the rest:

https://daacdata.apps.nsidc.org/pub/DATASETS/NOAA/G02135/

etcetera.

Wipneus, have you already switched your scripted data downloads to the HTTPS? If so, what method did you use to access the data?

Wipneus

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Re: 2017 sea ice area and extent data
« Reply #57 on: January 21, 2017, 09:12:27 AM »

Wipneus, have you already switched your scripted data downloads to the HTTPS? If so, what method did you use to access the data?

I am working on it, it is a major pain.

First NSIDC suggets using firefox (with "downthemall addin), wget or curl tools:
https://nsidc.org/support/faq/what-options-are-available-bulk-downloading-data-https-earthdata-login-enabled

That offers no solutions for my scripts, that streamlines the download with the processing of the data files. Http(s) is not a protocol designed for pure data access and  requires reading webpages, pseudo-sessions with authorization, handling cookies and  connection reuse.
I found that the "python-scripts" package does these things out of the box and am currently testing the solution. The https access is much slower than ftp (also with wget, it is not my sloppy programming), so I am using the multi-threading library "joblib" to speed things up a bit.



Pmt111500

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Re: 2017 sea ice area and extent data
« Reply #58 on: January 21, 2017, 09:25:25 AM »
interesting they're doing the transfer to inefficient https just now. They thus increase the costs of data transmission. I'll hazard a guess they'll use this totally unnecessary insertion of unsafe scripts as an excuse to cut down true science.
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Sourabh

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Re: 2017 sea ice area and extent data
« Reply #59 on: January 21, 2017, 01:22:17 PM »
If possible, can anyone post area numbers? What is happening to the area these days? :-\ :-\ :-\

Are we also experiencing shocking "recovery" in area as well?    ;) ;)

DavidR

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Re: 2017 sea ice area and extent data
« Reply #60 on: January 22, 2017, 08:39:18 AM »
Wipneus's area and extent graphs show that  most  of the recent  increase has occurred in the North Pacific.

https://sites.google.com/site/arctischepinguin/home/amsr2/grf/amsr2-area-regional.png

https://sites.google.com/site/arctischepinguin/home/amsr2/grf/amsr2-extent-regional.png

Within the Arctic basin there appears to  have been slight declines as predicted earlier.  Baffin and Greenland are up slightly but  many of the other seas are declining or flat. This suggests we will  see a year where the early decline will be similar to 2016 but the real  damage will appear when the central ice collapses when  summer comes.


jdallen

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Re: 2017 sea ice area and extent data
« Reply #61 on: January 22, 2017, 10:33:04 AM »
Wipneus's area and extent graphs show that  most  of the recent  increase has occurred in the North Pacific.
In short, the extent and area increases we've seen over the last few days (about 500K KM2) have mostly taken place in peripheral areas which will start melting out rapidly in 6-8 weeks.

Not a lot to be happy about there, I'm afraid.
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BornFromTheVoid

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Re: 2017 sea ice area and extent data
« Reply #62 on: January 22, 2017, 09:24:41 PM »
Update for the week to January 21st

The current 5 day trailing average is on 13,187,000km2 while the 1 day extent is at 13,373,000km2.

(All the following data is based on a trailing 5 day average)
The daily anomaly (compared to 81-10) is at -1,386,000km2, a decrease from -1,387,000km2 last week. The anomaly compared to the 07, 11 and 12 average is at -510,000km2, a decrease from -556,000km2 last week. We're currently lowest on record, the same last week.



The average daily change over the last 7 days was +40.1k/day, compared to the long term average of +39.9k/day, and the 07, 11 and 12 average of +33.5k/day.
The average long term change over the next week is +35.3k/day, with the 07, 11, and 12 average being +44.4k/day.



The extent increase so far this January is the 5th smallest on record. To achieve the largest increase, a gain of at least 109.1k/day is required (at least +113.1k/day with with single day values), while the smallest increase requires a gain of less than 15.2k/day (loss of at least 4.5k/day with single day values) and an average increase requires a gain of 64.0k/day (gain of 56.7k/day with single day values).


Ice Shieldz

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Re: 2017 sea ice area and extent data
« Reply #63 on: January 22, 2017, 10:59:17 PM »
BornFromTheVoid, that 7 Day Extent Change says a lot.  The line for 2016/17 has an exceptional wave sinuosity.  It would be very interesting to overlay markers for each major arctic storm, and see how they align with 2016/17 wave peaks and troughs.

cartographer

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Re: 2017 sea ice area and extent data
« Reply #64 on: January 23, 2017, 10:50:32 PM »
interesting they're doing the transfer to inefficient https just now. They thus increase the costs of data transmission. I'll hazard a guess they'll use this totally unnecessary insertion of unsafe scripts as an excuse to cut down true science.

There has been an effort throughout NOAA, at least, to move to https by year's end to improve data and system security. This was ongoing before the election and so shouldn't be seen as a consequence thereof.

Jim Pettit

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Re: 2017 sea ice area and extent data
« Reply #65 on: January 28, 2017, 05:13:36 PM »
Despite the recordsetting (for late January) increase in NH sea ice extent over the past two weeks, 2017 is still far ahead of the rest of the pack so far as the year-to-date/month-to-date daily average is concerned. Here's NSIDC:



Also despite that recordsetting increase, total extent change for the month is still running lower than the 2007-2016 average.

ADS-NIPR (IJIS) Extent:
13,077,599 km2 (27 January)
9,961,502 km2 above record minimum extent of 3,177,455 km2 (16 September 2012).
Down 61,358 km2 (-0.47%) from previous day.
Up 208,732 km2  (1.62%) over past seven days (daily average: 29,819 km2).
Up 980,803 km2  (8.11%) for January (daily average: 36,326 km2).
861,841 km2 below 2000s average for this date.
311,321 km2 below 2010s average for this date.
149,514 km2 below 2016 value for this date.
377,460 km2 below 2012 value for this date.
Lowest year-to-date (01 January - 27 January) average.
Lowest January to-date average.
Lowest value for the date.
18 days this year (66.67% year-to-date) have recorded the lowest daily extent.
7 days (25.93%) have recorded the second lowest.
0 days (0%) have recorded the third lowest.
« Last Edit: January 28, 2017, 05:57:02 PM by Jim Pettit »

BornFromTheVoid

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Re: 2017 sea ice area and extent data
« Reply #66 on: January 29, 2017, 03:11:40 PM »
Update for the week to January 28th

The current 5 day trailing average is on 13,714,000km2 while the 1 day extent is at 13,655,000km2.

(All the following data is based on a trailing 5 day average)
The daily anomaly (compared to 81-10) is at -1,106,000km2, a decrease from -1,386,000km2 last week. The anomaly compared to the 07, 11 and 12 average is at -294,000km2, a decrease from -510,000km2 last week. We're currently 2nd lowest on record, the same last week.



The average daily change over the last 7 days was +75.3k/day, compared to the long term average of +35.3k/day, and the 07, 11 and 12 average of +44.4k/day.
The average long term change over the next week is +34.4k/day, with the 07, 11, and 12 average being +23.7k/day.



The extent increase so far this January is the 18th smallest on record. To achieve the largest increase, a gain of at least 187.8k/day is required (at least +510.6k/day with with single day values), while the smallest increase requires a loss of at least 125.0k/day (loss of at least 271.3k/day with single day values) and an average increase requires a gain of 37.7k/day (gain of 135.5k/day with single day values).


Jim Pettit

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Re: 2017 sea ice area and extent data
« Reply #67 on: February 01, 2017, 01:40:56 PM »
January was another record-breaking month in the Arctic. Only slightly below average extent increase, but a far below noremal monthly average.

IJIS:



NSIDC:



IJIS extent is still roughly three-quarters of a million km2 below the low record maximum set in 2015 (and almost equalled again last year). With roughly six weeks of ice growth still to go (between two weeks [2015] and nine weeks [2010]), 2017 may or may not set a new record; five years out of the last ten saw enough extent increase after this date to set a new low maximum record, and the other half didn't. Far more importantly, however, is the fact that even with extent likely to spread, it's thin and it's frangible, and isn't likely to linger.

BornFromTheVoid

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Re: 2017 sea ice area and extent data
« Reply #68 on: February 05, 2017, 05:20:44 PM »
Update for the week to February 4th

The current 5 day trailing average is on 13,828,000km2 while the 1 day extent is at 13,834,000km2.

(All the following data is based on a trailing 5 day average)
The daily anomaly (compared to 81-10) is at -1,232,000km2, an increase from -1,106,000km2 last week. The anomaly compared to the 07, 11 and 12 average is at -345,000km2, an increase from -294,000km2 last week. We're currently lowest on record, up from 2nd lowest last week.



The average daily change over the last 7 days was +16.4k/day, compared to the long term average of +34.4k/day, and the 07, 11 and 12 average of +23.7k/day.
The average long term change over the next week is +21.1k/day, with the 07, 11, and 12 average being +23.2k/day.



The extent increase so far this February is the 19th smallest on record. To achieve the largest increase, a gain of at least 29.6k/day is required (at least +31.9k/day with with single day values), while the smallest increase requires a loss of at least 1.8k/day (loss of at least 2.3k/day with single day values) and an average increase requires a gain of 18.3k/day (gain of 19.7k/day with single day values)



The extent increase in January was the 13th smallest on record while the average extent was the lowest on record.



Wipneus

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Re: 2017 sea ice area and extent data
« Reply #69 on: February 08, 2017, 02:29:24 PM »
NSIDC area dropped -124k6, half of the loss in Okhotsk region.

Area graphs are rare after the CT stopped updating, attached is the spaghetti graph based on area calculated from NSIDC area.


DrTskoul

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Re: 2017 sea ice area and extent data
« Reply #70 on: February 08, 2017, 02:33:30 PM »
Thank you Wip for the rare delight....
“You can know the name of a bird in all the languages of the world, but when you're finished, you'll know absolutely nothing whatever about the bird... So let's look at the bird and see what it's doing -- that's what counts.”
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Pmt111500

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Re: 2017 sea ice area and extent data
« Reply #71 on: February 08, 2017, 03:18:29 PM »
Thanks Wipneus, I still prefer area graphs and values over extent mesh. Too bad ct sia is so hard to connect well to the current data formats. I've given up on that and just take what the good people here including you provide. Anyway my stat skills on the better programs than spreadsheet stuff is not there but thebsimple longperiod sets are easily analysed even by those who are not as good analysts as many here. There's imho nothing more convincing than calculating the reality of climate change yourself.
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Wipneus

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Re: 2017 sea ice area and extent data
« Reply #72 on: February 09, 2017, 02:45:20 PM »
"NSIDC area" second century drop in two days: -110k. CAB, Okhotsk and Greenland Sea.

Apocalypse4Real

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Re: 2017 sea ice area and extent data
« Reply #73 on: February 11, 2017, 02:21:13 AM »
Wipneus,

Great stuff! I review your graphs daily.

A4R

Chuck Yokota

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Re: 2017 sea ice area and extent data
« Reply #74 on: February 12, 2017, 04:56:53 AM »
Am I reading the graph correctly, that NSIDC area has been the record lowest every day since mid-October?

DrTskoul

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Re: 2017 sea ice area and extent data
« Reply #75 on: February 12, 2017, 05:15:34 AM »
Am I reading the graph correctly, that NSIDC area has been the record lowest every day since mid-October?

Yes... :o
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BornFromTheVoid

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Re: 2017 sea ice area and extent data
« Reply #76 on: February 12, 2017, 04:57:32 PM »
Update for the week to February 11th

The current 5 day trailing average is on 13,895,000km2 while the 1 day extent is at 13,864,000km2.

(All the following data is based on a trailing 5 day average)
The daily anomaly (compared to 81-10) is at -1,312,000km2, an increase from -1,232,000km2 last week. The anomaly compared to the 07, 11 and 12 average is at -441,000km2, an increase from -345,000km2 last week. We're currently lowest on record, the same as last week.



The average daily change over the last 7 days was +9.6k/day, compared to the long term average of +21.1k/day, and the 07, 11 and 12 average of +23.2k/day.
The average long term change over the next week is +17.4k/day, with the 07, 11, and 12 average being +33.3k/day.



The extent increase so far this February is the 11th smallest on record. To achieve the largest increase, a gain of at least 37.7k/day is required (at least +45.0k/day with with single day values), while the smallest increase requires a loss of at least 6.4k/day (loss of at least 5.3k/day with single day values) and an average increase requires a gain of 21.8k/day (gain of 26.8k/day with single day values).


Jim Pettit

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Re: 2017 sea ice area and extent data
« Reply #77 on: February 15, 2017, 03:17:08 PM »
A quick snapshot of an NSIDC Arctic SIE chart to show that, even with the big uptick the last few days, 2017 is still looking pretty weak and pathetic:


jdallen

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Re: 2017 sea ice area and extent data
« Reply #78 on: February 15, 2017, 04:55:27 PM »
If we get the forecast 7-10 days of "normal" temperatures, It wouldn't surprise me if area and extent spiked up as much as 500,000 KM2.  At this juncture, none of that ice formed is likely to get past 50CM of thickness.  None of the existing ice is likely to thicken more than about another 10CM.

When the weather turns, it will draw back just as rapidly.  QED, I expect we'll hit max around or about the 25th of February.
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Gray-Wolf

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Re: 2017 sea ice area and extent data
« Reply #79 on: February 15, 2017, 05:06:09 PM »
A sense a moment of Deja vu approaching!!

In 2012 the ice factory turned on around now and took extent on a little excursion.

Deniers went bonkers with their demands for a 'recovery' to be accepted even though we all told then that late extension, outside basin ice would make no difference to the final figures.

They went very quiet after that right up until the storm arrived and then they tried to claim the whole of the melt seasons behaviour boiled down to the impacts of that 1 storm..........

With the Arctic so much in the news this winter I very much fear that any signs of the ice extent/area approaching 'average' will set them off again?

We all know we have a very bad , potentially disastrous if the weather favours melt/export, so having to put them straight for the first 6 weeks of melt season will be wearing!!!
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Shared Humanity

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Re: 2017 sea ice area and extent data
« Reply #80 on: February 16, 2017, 12:24:24 AM »
A sense a moment of Deja vu approaching!!

In 2012 the ice factory turned on around now and took extent on a little excursion.

Deniers went bonkers with their demands for a 'recovery' to be accepted even though we all told then that late extension, outside basin ice would make no difference to the final figures.

They went very quiet after that right up until the storm arrived and then they tried to claim the whole of the melt seasons behaviour boiled down to the impacts of that 1 storm..........

With the Arctic so much in the news this winter I very much fear that any signs of the ice extent/area approaching 'average' will set them off again?

We all know we have a very bad , potentially disastrous if the weather favours melt/export, so having to put them straight for the first 6 weeks of melt season will be wearing!!!

Don't set them straight. Let them spout their nonsense and stew in their own juices when their ignorance becomes obvious.

RoxTheGeologist

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Re: 2017 sea ice area and extent data
« Reply #81 on: February 16, 2017, 03:08:36 AM »

Extent is a dangerously noisy value to base Climate Change arguments on; in winter it will recover, it's cold enough to freeze the top layer of the ocean and extent changes dramatically depending on the weather. It hands the prerogative back to the deniers whenever there is a week of cold weather. It would be better to shift the argument to volume or to FDDs. We know that the arctic sea ice is the canary in the coal mine and that it is the place where climate change is most easily observed. Why do we continue to argue about the one parameter that actually does not correlate well with FDDs?

Iceismylife

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Re: 2017 sea ice area and extent data
« Reply #82 on: February 16, 2017, 04:04:06 AM »

Extent is a dangerously noisy value to base Climate Change arguments on; in winter it will recover, it's cold enough to freeze the top layer of the ocean and extent changes dramatically depending on the weather. It hands the prerogative back to the deniers whenever there is a week of cold weather. It would be better to shift the argument to volume or to FDDs. We know that the arctic sea ice is the canary in the coal mine and that it is the place where climate change is most easily observed. Why do we continue to argue about the one parameter that actually does not correlate well with FDDs?
Tell that to the IPCC.  They define ice free in extent.

JMP

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Re: 2017 sea ice area and extent data
« Reply #83 on: February 16, 2017, 05:09:23 AM »

Extent is a dangerously noisy value to base Climate Change arguments on; in winter it will recover, it's cold enough to freeze the top layer of the ocean and extent changes dramatically depending on the weather. It hands the prerogative back to the deniers whenever there is a week of cold weather. It would be better to shift the argument to volume or to FDDs. We know that the arctic sea ice is the canary in the coal mine and that it is the place where climate change is most easily observed. Why do we continue to argue about the one parameter that actually does not correlate well with FDDs?
Tell that to the IPCC.  They define ice free in extent.
Point taken. 
But.  I'm thinking that the scientists of the IPCC understand what's going on even if that's not explicitly reflected in statements to the public.  There are references to thickness and concentration on their site for instance - though a search for extent, even, returned no results from their home page.  I seriously doubt the scientists/science comprehension at the IPCC are/is the difficulty.  Blah blah blah.

Let's not overlook that Rox has a great point here! 

Extent should almost come with a disclaimer imho. Particularly because late season gains have been mischaracterized as legitimate recovery.  And, while it may all be a bit difficult to get at first glance, thickness, area, extent, and volume, are all readily comprehensible terms that I've never seen delineated or discussed in the regular media.  And so I think too, facilitating the discussion of these terms is in everyone's interest.

Feeltheburn

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Re: 2017 sea ice area and extent data
« Reply #84 on: February 16, 2017, 05:35:38 AM »

Extent is a dangerously noisy value to base Climate Change arguments on; in winter it will recover, it's cold enough to freeze the top layer of the ocean and extent changes dramatically depending on the weather. It hands the prerogative back to the deniers whenever there is a week of cold weather. It would be better to shift the argument to volume or to FDDs. We know that the arctic sea ice is the canary in the coal mine and that it is the place where climate change is most easily observed. Why do we continue to argue about the one parameter that actually does not correlate well with FDDs?

Good point. However, I believe DMI modeled ice thickness, for example, only goes back to 2003, while ice extent goes back to 1979 (unofficially back to 1974?), so ice extent may be the only way to compare apples and apples all the way back to 1979. Please someone correct me if I'm wrong and point to where we can find reliable ice thickness data as far back as 1979.
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oren

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Re: 2017 sea ice area and extent data
« Reply #85 on: February 16, 2017, 07:17:11 AM »
The IPCC focuses on summer extent which does correlate with AGW. Winter extent (at this stage at least) is mostly semi-random numbers in the periphery. The current long-term process of the arctic is turning large parts of it (all of it eventually) to be seasonally ice-free. Some parts are undergoing change to almost year-round ice-free, but that is still very limited (mainly Barents area).

DoomInTheUK

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Re: 2017 sea ice area and extent data
« Reply #86 on: February 16, 2017, 10:16:06 AM »

...We know that the arctic sea ice is the canary in the coal mine .....

The way it's looking at the moment, it's more of a canary in a taxidermists.  :)

Neven

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Re: 2017 sea ice area and extent data
« Reply #87 on: February 16, 2017, 10:35:33 AM »
Good point. However, I believe DMI modeled ice thickness, for example, only goes back to 2003, while ice extent goes back to 1979 (unofficially back to 1974?), so ice extent may be the only way to compare apples and apples all the way back to 1979. Please someone correct me if I'm wrong and point to where we can find reliable ice thickness data as far back as 1979.

There are obviously no observations (except perhaps for submarine data), but PIOMAS has modelled data going back that far, I believe.
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Gray-Wolf

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Re: 2017 sea ice area and extent data
« Reply #88 on: February 16, 2017, 11:42:38 AM »
I think this sudden need for accurate data of the old Arctic is suspect? We have plenty of ships data describing the scale of the ice from the 1800's onward and we know that there is nothing like the conditions witnessed then anywhere in the basin now. All we know is that the slow 'drip ,drip' forcing through the 20th Century did away with all of that ice, ice big enough to build military bases ans radar station on!( the 'T' islands).

Sadly I believe this is an attempt to set up a straw man.

The fact that we had a hell of a lot more ice, some truly massive chunks from Ward Hunt etc. and all of that ice is gone. We are not only at the rump end of the pack it would appear that we now have a 'different pack' of thinner, warmer, younger ice to that of the last Century.
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seaicesailor

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Re: 2017 sea ice area and extent data
« Reply #89 on: February 16, 2017, 12:17:38 PM »
... All we know is that the slow 'drip ,drip' forcing through the 20th Century did away with all of that ice, ice big enough to build military bases ans radar station on!( the 'T' islands)....
Nice that you point that out. In particular, Fletcher (T-3) Ice Island lasted from 1946 to 1983. It was a 14x8 km iceberg, with an estimated thickness of 50 to 60 m, and its stability allowed for harboring meteo stations, military base,...
It seems difficult to imagine how a loose drifting piece of ice whatever its origin would survive for 20 almost 40 years in the current Arctic.
https://en.wikipedia.org/wiki/Fletcher's_Ice_Island
Excuses for the (nice) off topic
PS. The origin of this island as well as many others documented in the mid 20th century, was the Ellesmere Ice Shelf, which split and disintegrated from 2002 to 2008 in many pieces.
https://en.wikipedia.org/wiki/Ellesmere_Ice_Shelf
PPS. The last image shows the drift of T-3 from early 50's to 1975. It basically spent 20+ years in regions of the Gyre that have become seasonally ice-free nowadays. Perspective!
« Last Edit: February 16, 2017, 02:23:53 PM by seaicesailor »

DrTskoul

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Re: 2017 sea ice area and extent data
« Reply #90 on: February 16, 2017, 12:22:55 PM »
All this renewed discussion about Area, Extent, Volume, newly added FDDs, is a recurring feature in the forum.  Whenever uncertainty is high we start questioning again. What has been established in the previous cycle of discussion.

All the important observational data from 1800s to the early 80s (charts, expedition information, later submarine thickness data and satellite images, all point to the same picture of ice and thickness and area abundance and define the box.  Today's arctic is so far from those box boundaries that it does not even matter to accurately represent those edges for the analysis of our current dire state. We are too impatient and the natural noise frequency too small to satisfy our impatience. However the forcings are set and known and the internal variability irrelevant to the final outcome.

Going back and questioning what the ice was in the 70s and 80s is unnecessary... It has been documented in the prior posts in this Forum. Search is your friend...

Our best bet is to try and see if we can understand the mechanisms of this spurts of ups and downs. It is a window to the internal variability drivers. Lots to learn there.

And another comment. FDDs are a great probe of the average state of the arctic.  Localised over small areas lessens the usefuleness, since advection of ice comes into play.  Locally high FDDs mean nothing if the ice is mobile and has a small residence time in the high FDD zone.  Conversly, low FDDs and slow moving ice is a recipe for a disaster..
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gerontocrat

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Re: 2017 sea ice area and extent data
« Reply #91 on: February 16, 2017, 03:50:59 PM »
FDD's, extent, volume, area etc.

50 years ago I was at University doing Pure Maths. Maybe then I could have done the maths that forms a large part of this forum. But now this tired old brain cannot. The only maths I do these days can be done on a 2 quid calculator (though I have been known to occasionally venture into cubic measures).

However, I read a large proportion of these posts and classify them by using a simple statistical ranking analysis. North is arctic ice recovery, South is where we are going. So the current FDD anomaly points strongly South. The last three months PIOMAS volumes point very strongly South because of a) persistence and b) happening in winter. The DMI graph for 80+ North points strongly South because it is not just one winter. The last couple of days increase in sea ice extent - a small North but offset by strong sea ice drift dispersing and breaking up parts of the ice cap.

And so on and so on. The speculative conclusion is that Winter Sea Ice is showing increased decline, with presumable a major impact on summer ice . But with a caveat. Archaeologists have a rule when they are digging - "It takes three bricks to make a wall". Perhaps speculation on a new winter sea ice environment can only become a hypothesis when we see three significant record low years close together?

A slow-motion train wreck is - slow. Mind you as a total hypocrite I am on tenterhooks waiting for the PIOMAS February volume reporrt.



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Jim Williams

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Re: 2017 sea ice area and extent data
« Reply #92 on: February 16, 2017, 04:06:30 PM »
And so on and so on. The speculative conclusion is that Winter Sea Ice is showing increased decline, with presumable a major impact on summer ice . But with a caveat. Archaeologists have a rule when they are digging - "It takes three bricks to make a wall". Perhaps speculation on a new winter sea ice environment can only become a hypothesis when we see three significant record low years close together?

When I look at the DMI 80N since the beginning of 2016 I count 9 bricks.  The bottom temp simply has not been able to break through 247 in 9 tries.

josh-j

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Re: 2017 sea ice area and extent data
« Reply #93 on: February 16, 2017, 09:04:40 PM »
When I look at the DMI 80N since the beginning of 2016 I count 9 bricks.  The bottom temp simply has not been able to break through 247 in 9 tries.

Indeed DMI 80N has not dropped below the green line (in winter) since December 2015. :o

I can't see any year other than 2016 that has the property of being always above average in DMI 80N (well, there is also 2017 so far..). However I don't have the knowledge to make my speculation worth much if I was to start predicting next winter!

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Re: 2017 sea ice area and extent data
« Reply #94 on: February 17, 2017, 12:33:59 AM »
When I look at the DMI 80N since the beginning of 2016 I count 9 bricks.  The bottom temp simply has not been able to break through 247 in 9 tries.

Indeed DMI 80N has not dropped below the green line (in winter) since December 2015. :o

I can't see any year other than 2016 that has the property of being always above average in DMI 80N (well, there is also 2017 so far..). However I don't have the knowledge to make my speculation worth much if I was to start predicting next winter!
It hasn't dropped to the green line...forget below it (in winter).  It has consistently stopped about five degrees above the previous average.

There has got to be something physical about that even if we have not figured out what or why.

BornFromTheVoid

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Re: 2017 sea ice area and extent data
« Reply #95 on: February 19, 2017, 04:34:51 PM »
Update for the week to February 18th

The current 5 day trailing average is on 14,238,000km2 while the 1 day extent is at 14,304,000km2.

(All the following data is based on a trailing 5 day average)
The daily anomaly (compared to 81-10) is at -1,091,000km2, a decrease from -1,312,000km2 last week. The anomaly compared to the 07, 11 and 12 average is at -330,000km2, a decrease from -441,000km2 last week. We're currently 2nd lowest on record, down from lowest last week.



The average daily change over the last 7 days was +49.0k/day, compared to the long term average of +17.4k/day, and the 07, 11 and 12 average of +33.3k/day.
The average long term change over the next week is +19.0k/day, with the 07, 11, and 12 average being +12.1k/day.



The extent increase so far this February is the 13th largest on record. To achieve the largest increase, a gain of at least 29.8k/day is required (at least +29.1k/day with with single day values), while the smallest increase requires a loss of at least 45.3k/day (loss of at least 64.8k/day with single day values) and an average increase requires a gain of 2.8k/day (loss of 4.7k/day with single day values).



Tor Bejnar

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Re: 2017 sea ice area and extent data
« Reply #96 on: February 19, 2017, 11:52:22 PM »
BFTV's weekly summaries, especially the one showing the relatively extreme ups and downs of daily ice growth (over the course of several days), makes it clear to me that making weekly projections based on last week's extent and area growth numbers is a fool's errand.  It seems a best guess for growth over a week's time would be made by using the 30-year average for this time of year than using last week's or any few year's average, even though we are in record or near-record extent (and area) territory. 

So thank you very much BFTV.

Some, of course, are paying attention to weather and weather forecasts, and making forecasts of ice growth on these.  (I don't have the knowledge or skills to do this [nor patience, yet, to learn].)
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Re: 2017 sea ice area and extent data
« Reply #97 on: February 22, 2017, 02:52:12 PM »
NSIDC extent has plateaued a bit after last week's robust gains, and is still running far below (>2 standard deviations) the long-term mean.



In the meantime. despite those recent increases, NSIDC's 2017-to-date average is substantially lower than all previous years:



If the remainder of the 2017 refreeze season were to duplicate the average behavior of the last ten years (2007-2016), this year's maximum would be a new record low one of 14.498M km2, and it would occur on 17 March.


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Re: 2017 sea ice area and extent data
« Reply #98 on: February 22, 2017, 03:06:44 PM »
NSIDC extent has plateaued a bit after last week's robust gains, and is still running far below (>2 standard deviations) the long-term mean.


I have even begun to wonder if the 2017 extent maximum might be around here somewhere:

http://GreatWhiteCon.info/2017/02/the-2017-arctic-sea-ice-maximum-extent/

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Jim Pettit

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Re: 2017 sea ice area and extent data
« Reply #99 on: February 22, 2017, 07:44:13 PM »
I have even begun to wonder if the 2017 extent maximum might be around here somewhere:

http://GreatWhiteCon.info/2017/02/the-2017-arctic-sea-ice-maximum-extent/

Crow pie time RSN?


I wouldn't place any bets at the moment, but it's certainly possible. A few previous years had already seen their maximum by this daye, and several more occur in the next week, including 2007 and 2016. (The latest maximum in recent years was 2010's March 31 peak. That's still five and a half weeks away.