Home brew AMSR2 extent & area calculation

[Wipneus]

A quick visit to climate Reanalizer reveals that airflow is just below or close zero C. No more refreeze, I think.

I guessed myself (visually from CR) somewhere from -15 to -10 ^oC.

By a more precise method (using the Gimp, use a tool replace to specific color) it is probably mostly between -19 to -15 ^oC.

Please be more careful.

So it is probably still freezing.
 

[jdallen]

A quick visit to climate Reanalizer reveals that airflow is just below or close zero C. No more refreeze, I think.

I guessed myself (visually from CR) somewhere from -15 to -10 ^oC.

By a more precise method (using the Gimp, use a tool replace to specific color) it is probably mostly between -19 to -15 ^oC.

Please be more careful.

So it is probably still freezing.

Apologies and Understood - I was looking more to the west as well, mostly over the Kara which would also skew my view.

[Wipneus]

Update 20150311.
Changes from 20150304.

Extent: -82.8 (-183k vs 2014, -847k vs 2013, -747k vs 2012)
Area: -149.2 (-93k vs 2014, -915k vs 2013, -735k vs 2012)

Again a week with almost continuous decline in sea ice area and extent. Both area and extent are now below the previous (since 2012) years. The distances from 2014 levels are modest, but that may change during the coming week when 2014 saw a sudden spurt and both area and extent grew by about 530k in a few days. A repeat of that event would establish a new maximum for extent and area would be equal to the current max reached on Feb 16.
Regionally the epi-center of the decline is the Barents Region with the Kara in second place. Low pressure over Svalbard draws mild winds in from the Atlantic, causing ice transport into the the central Arctic. Temperatures are anomalous high, but still below zero. The big drops are not caused by melt.
Increases where in the Bering and the Baffin regions. Over the Bering Sea winds are now from the north and have caused a recovery from the losses in the last two week.
 
You will find the updated graphs in the top post

The details (in 1000 km²):


Extent:
   Central Arctic Basin       East Siberian Sea              Laptev Sea
                  -16.9                    -1.2                   -23.8
               Kara Sea             Barents Sea           Greenland Sea
                  -46.8                  -166.3                   -11.5
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
                   53.6                    21.5                     3.5
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
                   -1.4                     1.0                     0.0
             Bering Sea          Sea of Okhotsk            Total Extent
                  127.8                   -22.4                   -82.8

Area:
   Central Arctic Basin       East Siberian Sea              Laptev Sea
                  -92.7                    -1.3                   -58.2
               Kara Sea             Barents Sea           Greenland Sea
                  -77.5                  -160.3                    -4.2
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
                   48.1                    31.8                     8.9
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
                    2.5                    12.6                     6.6
             Bering Sea          Sea of Okhotsk              Total Area
                  128.3                     6.2                  -149.2

[Wipneus]

Sea ice in the regions surrounding the Barents Sea compared with a year ago. The similarities are obvious: highly mobile ice is constantly moving with the changing wind directions. There is now more ice near Svalbard and in front of the Victoria Channel. Less ice is found on the Russian coast.

(give it a click please)

[LRC1962]

Sea ice in the regions surrounding the Barents Sea compared with a year ago. The similarities are obvious: highly mobile ice is constantly moving with the changing wind directions. There is now more ice near Svalbard and in front of the Victoria Channel. Less ice is found on the Russian coast.

Wouldn't that be showing us the results of the cyclones tracking into that area? General winds sucking ice into the area, then the spin would clear out the 'upper right' side spinning it anti-clockwise into open water.
Mobility of the ice would idicate somewhat the weakness of the ice, but also the strength of the storms hitting there.
Can not remember so many cyclones hitting that area so often this time of year last year.

[Sleepy]

A bit late to majava's question in #1449 above, but you can also check SMHI. They provide daily icecharts here as well as archived icecharts.
http://www.smhi.se/klimatdata/oceanografi/havsis

Today 20150315.
http://www.smhi.se/oceanografi/istjanst/produkter/arkiv/sstcolor/sstcolor_20150315.pdf
For the same date in 2008.
http://www.smhi.se/oceanografi/istjanst/produkter/arkiv/sstcolor/sstcolor_20080315.pdf
Maximum in 2008 (there's also a color coded for that date).
http://www.smhi.se/oceanografi/istjanst/produkter/arkiv/maxis/maxis_2008.pdf

And for comparison, the maximum in 20110225.
http://www.smhi.se/oceanografi/istjanst/produkter/arkiv/maxis/maxis_2011.pdf
And the maximum in 19870313.
http://www.smhi.se/oceanografi/istjanst/produkter/arkiv/maxis/maxis_1987.pdf

Maximum extent 1957-2014.

[Wipneus]

The ice in the Hudson Bay region is melting and moving under the passage of a cyclone. Both extent and area have dropped suddenly, with the latter dropping most.

[plinius]

The ice in the Hudson Bay region is melting and moving under the passage of a cyclone. Both extent and area have dropped suddenly, with the latter dropping most.

would say that's rather stacking then melting. Looks also like very weak, but present thin ice formation in the polynya. Nevertheless, quite remarkable that this can open so far at this time of the year...

[Wipneus]

The ice in the Hudson Bay region is melting and moving under the passage of a cyclone. Both extent and area have dropped suddenly, with the latter dropping most.

would say that's rather stacking then melting. Looks also like very weak, but present thin ice formation in the polynya. Nevertheless, quite remarkable that this can open so far at this time of the year...

Plinius, perhaps you are right, but I have pointed in the "2015 area and extent thread" that there are indications of melt: the Jaxa ice thickness/melt map and the fact that the NSIDC Nasa Team sea ice concentration algorithm shows a much stronger drop than Jaxa's and this calculation.

[Wipneus]

Update 20150318.
Changes from 20150311.

Extent: +71.4 (-444k vs 2014, -768k vs 2013, -861k vs 2012)
Area: -0.2 (-427k vs 2014, -899k vs 2013, -836k vs 2012)

A small increase in total extent cannot prevent that the gap with 2014 was greatly increased, 2014 saw a huge jump in this week.. Regionally most of the extent increase was in the Bering Sea region. Area did not reach a net increase because a rather large drop in area, though not a big as seen in the NSIDC sea ice concentration product. Extent is now -277k the max set in mid February, area is -519k behind. A late maximum is getting less and less likely, now the spring equinox  is almost there.
 
You will find the updated graphs in the top post

The details (in 1000 km²):


Extent:
   Central Arctic Basin       East Siberian Sea              Laptev Sea
                   42.7                     0.4                    19.9
               Kara Sea             Barents Sea           Greenland Sea
                   -3.9                    16.5                    12.9
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
                   13.6                   -27.4                   -38.4
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
                   -1.9                    -0.1                     0.0
             Bering Sea          Sea of Okhotsk            Total Extent
                   43.4                    -6.3                    71.4

Area:
   Central Arctic Basin       East Siberian Sea              Laptev Sea
                   79.0                     0.2                    34.2
               Kara Sea             Barents Sea           Greenland Sea
                  -28.7                    19.2                    10.7
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
                   -3.5                   -39.6                  -106.3
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
                   -4.0                    -0.5                     3.1
             Bering Sea          Sea of Okhotsk              Total Area
                   46.4                   -10.4                    -0.2

[Wipneus]

A high over Beaufort seems to be starting of "the Gyre".

[Tor Bejnar]

... now the spring equinox  is almost there.

Our Kiwi and Aussi mates (and other Southern Hemisphere associates) would appreciate this nuance!

[Siffy]

Out of interest when does the beaufort Gyre normally start up? Is it early or is this around the expected time frame?

[anthropocene]

I suppose it depends what you mean by the gyre. The main point is that we wouldn't have been able to see it in previous years because the ice would have been jammed in solid and/or 100% coverage so if it did move it would not show.

[Siffy]

I suppose it depends what you mean by the gyre. The main point is that we wouldn't have been able to see it in previous years because the ice would have been jammed in solid and/or 100% coverage so if it did move it would not show.

Well that's what I mean, when was it visible like this in previous years? is this quite early to be able to see the ice pack being mobile in this way?

[Jim Hunt]

Well that's what I mean, when was it visible like this in previous years? is this quite early to be able to see the ice pack being mobile in this way?

You may wish to take a look at this thread in general:

http://forum.arctic-sea-ice.net/index.php/topic,94.0.html

and this animation in particular:



Of course A-Team got there first!

http://neven1.typepad.com/blog/2013/03/the-cracks-of-dawn.html

[Neven]

Out of interest when does the beaufort Gyre normally start up? Is it early or is this around the expected time frame?

Siffy, the Beaufort Gyre starts and stops in all seasons, depending on which way the wind blows, and this depends of atmospheric pressure. If a high-pressure area settles over the Beaufort Sea for an extended period the wind will blow in a clockwise motion and the sea ice follows the wind. This then is the Beaufort Gyre that takes the multi-year ice away from the Canadian Archipelago and pushes it towards Siberia, where it used to survive, but not anymore.

I've written a blog post on the Beaufort Gyre during the ASIB's first melting season here.

[Wipneus]

A dark feature develops north of the Fram.

[Neven]

I'm not seeing anything on LANCE-MODIS, but it's cloudy and I might be looking in the wrong place. What could be causing it?

[Espen]

Maybe the goat-head, remember it is the year of the Goat ;)

or maybe just a very special cloud-system just passing by?

[Jim Hunt]

Here's how Sentinel sees the area:

[viddaloo]

Here's how Sentinel sees the area:

Great! Can I ask again what the long white stripy features are? Ice, but what shape of ice, what causes them?

[jdallen]

I'm not seeing anything on LANCE-MODIS, but it's cloudy and I might be looking in the wrong place. What could be causing it?

As its persistent, my speculation would suggest an artifact of precipitation, most likely snowfall.

[Jim Hunt]

Can I ask again what the long white stripy features are? Ice, but what shape of ice, what causes them?

Ice that successfully scatters microwaves. Pressure ridges would be my guess, but I'm no expert.

In this context I'm looking for dark areas indicative of lack of scattering. Very young or absent ice

[johnm33]

A dark feature develops north of the Fram.

My guess, the recent cyclone there dumped enough snow to push it's thin ice 'foundation' deep enough to melt, that snow is now being chewed up by waves and wind and dissolved by seaspray.

[viddaloo]

Same dark hole in a NOAA image:

[Wipneus]

Winds are spreading the sea ice in the Bering Sea, but the ice edge gets only so far.

(click required)

[jdallen]

Winds are spreading the sea ice in the Bering Sea, but the ice edge gets only so far.

If the wind persists, we'll lose all the Bering ice in a real hurry... Not much moving in from the Chukchi to replace it...

[Neven]

Winds are spreading the sea ice in the Bering Sea, but the ice edge gets only so far.

(click required)

Must be the SSTs, otherwise we would've definitely seen a later maximum by now.

[LRC1962]

You could be getting a double whammy. The Alaskan Current is anomalously warm this year to the tune of 3C+ along the Canadian coast and you are having very warm weather in Alaska as many parts are actually reporting more rain than snow.
An Article talking about this winter in Alaska. If both air and sea are warmer then normal, then chances of getting ice I would think be very low indeed. Also makes me wounder what the summer would hold for that area.

[DavidR]

Winds are spreading the sea ice in the Bering Sea, but the ice edge gets only so far.

(click required)

Must be the SSTs, otherwise we would've definitely seen a later maximum by now.

SST's in the Bering were hottest on record for almost every month in the second half of last year. It's not surprising there has been strong resistance to growth there.

[Wipneus]

On the other side the ice in the St. Lawrence Bay is being played by the winds. There are some "flashes" of grey, not ice but probably some instrumental hiccup. The "ghost ice filter" part of the calculation is effective in removing it before the extent and area summings are done..

[Wipneus]

Update 20150325.
Changes from 20150318.

Extent: +83.6 (-196k vs 2014, -351k vs 2013, -720k vs 2012)
Area: +175.5 (-212k vs 2014, -389k vs 2013, -758k vs 2012)

Total sea ice extent and area both increased this week, but the preliminary maximum is not in any danger: the distance of about -300k seems safe. Conditions were favorable for increases though with winds blowing the ice southward both on the Pacific as the North Atlantic regions. Barents and Kara regions complied, but the growing melting powers seem to be too strong for Bering, Okhotsk, St. Lawrence and the Baffin regions. 
 
You will find the updated graphs in the top post

The details (in 1000 km²):


Extent:
   Central Arctic Basin       East Siberian Sea              Laptev Sea
                   16.9                    -1.2                     1.9
               Kara Sea             Barents Sea           Greenland Sea
                   54.9                   221.9                     3.4
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
                 -130.4                   -67.0                    10.4
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
                   -1.9                     0.1                     0.0
             Bering Sea          Sea of Okhotsk            Total Extent
                   -6.5                   -18.8                    83.6

Area:
   Central Arctic Basin       East Siberian Sea              Laptev Sea
                   58.9                    -3.2                     3.5
               Kara Sea             Barents Sea           Greenland Sea
                  140.2                   191.7                    16.3
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
                 -154.4                   -52.4                    42.1
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
                   -9.4                     0.9                    -0.5
             Bering Sea          Sea of Okhotsk              Total Area
                  -54.8                    -3.6                   175.5

[Wipneus]

Ice expanding in the Barents Sea. See how Novaya Zemlya is at one time nearly clear of the ice and gets packed later on. The dark feature north of the Fram is still visible and makes the movement towards that strait clearly visible.

(give it a click to animate)

[Wipneus]

Jaxa announced new versions of many AMSR2 products. Until now I have only noticed no products at all (in the public accessible archives).

How about the data source that Uni Hamburg uses to produce the ASI sea ice concentration maps? Looking at the latest data, it seems something stopped there as well.

[Wipneus]

Uni Hamburg data has resumed.

Ice extent reached on March 27 to 13.69313 Mm². That is only 45k short of the maximum reached in February.

In the mean time a sequence of the Canadian Archipelago compared with 2014. The difference in position of the Nares Strait Arch can be seen. The arch in the Barrow Strait/Lancaster Sound is much further in. On the other side the mobility edge in the Amundsen Gulf reached further last year.

(click required)

[jplotinus]

Thank you for the above CA comparison :-)
In looking at no other data than weather for various places in Nunavut and NWT, it appears it has been persistently cold in the archipelago region (in the inhabited portions large enough to have weather reported), with temps staying in the -20s throughout the region for weeks, and not much change coming in next 10 days, based on what I've seen. Not much melting going on, but I wonder if there's anything left to freeze that might impact extent/area?

[Wipneus]

Thank you for the above CA comparison :-)
In looking at no other data than weather for various places in Nunavut and NWT, it appears it has been persistently cold in the archipelago region (in the inhabited portions large enough to have weather reported), with temps staying in the -20s throughout the region for weeks, and not much change coming in next 10 days, based on what I've seen. Not much melting going on, but I wonder if there's anything left to freeze that might impact extent/area?

jp, I don,t know if it answers your question, but you could have a look at the regional graphs. From it you can see the ice extent and area in the CAA have hit the max (with a few little blips downward when some temporary open water forms)

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

[Wipneus]

The mysterious triple horned dark feature north of Fram still exists and is slowly drifting to the Strait (although one of the "horns" has faded).

[slow wing]

It's the son of the goat from seasons past! 

[werther]

Ah... the 'goat reversed', because then it was real ice, now it looks like the opposite...

[Neven]

I'm still not able to discern anything on LANCE-MODIS (although I am seeing some major cracking in the Beaufort).

[epiphyte]

I'm still not able to discern anything on LANCE-MODIS (although I am seeing some major cracking in the Beaufort).

Maybe they're not in on the joke

[Wipneus]

Update 20150401.
Changes from 20150325.

Extent: +45.7 (+60k vs 2014, -258k vs 2013, -640k vs 2012)
Area: +67.6 (+236k vs 2014, -266k vs 2013, -598k vs 2012)

A late growth in extent created a second max on March 27, only -45k below the all season max reached on Feb 15. That is less than the thickness of the lines I use in the extent plot. Area stayed much further below,even if its growth does not seem to be over. The distance on April 1 was still -275k  below the February max, so the chance of exceeding that are low.
Regionally growth was mostly in the Baffin region,  followed by the Pacific regions Bering and Okhotsk. Strong declines were in the Barents and St.Lawrence regions.
 
You will find the updated graphs in the top post

The details (in 1000 km²):


Extent:
   Central Arctic Basin       East Siberian Sea              Laptev Sea
                  -17.4                     2.0                     2.0
               Kara Sea             Barents Sea           Greenland Sea
                  -14.1                   -91.1                   -12.1
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
                  119.3                   -29.7                    26.1
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
                    6.1                     0.0                    -0.8
             Bering Sea          Sea of Okhotsk            Total Extent
                   33.6                    21.8                    45.7

Area:
   Central Arctic Basin       East Siberian Sea              Laptev Sea
                   -6.1                     5.9                    11.2
               Kara Sea             Barents Sea           Greenland Sea
                  -23.1                   -77.2                   -45.9
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
                  134.6                   -21.5                    56.7
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
                    3.1                    -6.2                   -10.7
             Bering Sea          Sea of Okhotsk              Total Area
                   52.8                    -6.1                    67.6

[Wipneus]

Clockwise winds around a high pressure system has sent the Beaufort Gyre into a spin.

[solartim27]

Not looking good over by Fram, no sign of any goats, but I think it would be out of the frame.
Any ideas about Polar View or Sentinel?

[Wipneus]

No data update from Uni Hamburg since April 2. I guess we will have to wait until they adjust for the version 2.1 of AMSR2 data.

[Wipneus]

The data updates seem to have restarted. There was not enough reliable data for a weekly summary though. The melts seem to have been strong though, on both the Atlantic and the Pacific regions as the attached delta map shows.

[Wipneus]

Once again my data source, the sea ice concentration calculated from AMSR2 data by Uni Hamburg, has been restored.
In time to watch the "son of goat", approaching the Fram Strait. Still unknown what is is,  it seems to visible only in the ~90GHz microwave band, unlike the goat head from 2013 that was best visible in Jaxa's RGB(36V,36H,18V) images.

[Sleepy]

Isn't it this feature?