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Wipneus

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Re: Home brew AMSR2 extent & area calculation
« Reply #3150 on: August 08, 2017, 12:33:13 PM »
Yesterday's comment mostly still apply. In addition more extent is lost in the ESS/Laptev "bite".

Update 20170807.

Extent: -101.4 (+133k vs 2016, -91k vs 2015, -665k vs 2014, -503k vs 2013, +462k vs 2012)
Area: -83.6 (+220k vs 2016, +94k vs 2015, -624k vs 2014, -605k vs 2013, +577k vs 2012)
 
The details (in 1000 km2):


Extent:
   Central Arctic Basin       East Siberian Sea              Laptev Sea
                  -45.9                   -10.5                    -9.5
               Kara Sea             Barents Sea           Greenland Sea
                   -3.3                     1.9                   -11.0
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
                   -4.9                     0.0                    -8.3
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
                  -10.5                     1.7                    -1.2
             Bering Sea          Sea of Okhotsk            Total Extent
                    0.0                     0.0                  -101.4

Area:
   Central Arctic Basin       East Siberian Sea              Laptev Sea
                  -52.0                   -17.2                   -10.5
               Kara Sea             Barents Sea           Greenland Sea
                   -0.7                     3.7                    -9.5
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
                   -0.2                     0.0                    -2.6
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
                  -19.4                    25.2                    -0.3
             Bering Sea          Sea of Okhotsk              Total Area
                    0.0                     0.0                   -83.6


Delta map attached: red/blue means the concentration went below/over the 15% cut-off. Reddish/bluish means the concentration decreased/increased by more than 7%.

Same detail is chosen, showing the continuing losses in the CAB.

Tor Bejnar

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Re: Home brew AMSR2 extent & area calculation
« Reply #3151 on: August 08, 2017, 07:54:07 PM »
Interesting stripes of pale red and pale blue.  This suggests to me a shift of loose medium concentration ice moving from the red towards the blue over the previous day. 

But why the alternating stripes?  Cloud effects?  (if so, that would mean my above 'suggestion' is wrong: nothing happening on the ground - just enjoy the pretty pictures.  Focus on the big picture.)
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Shared Humanity

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Re: Home brew AMSR2 extent & area calculation
« Reply #3152 on: August 08, 2017, 08:11:09 PM »
Interesting stripes of pale red and pale blue.  This suggests to me a shift of loose medium concentration ice moving from the red towards the blue over the previous day. 

But why the alternating stripes?  Cloud effects?  (if so, that would mean my above 'suggestion' is wrong: nothing happening on the ground - just enjoy the pretty pictures.  Focus on the big picture.)

Wind driven waves causing pulverized ice to congregate in bands of higher concentration?

Sterks

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Re: Home brew AMSR2 extent & area calculation
« Reply #3153 on: August 08, 2017, 08:12:57 PM »
Interesting stripes of pale red and pale blue.  This suggests to me a shift of loose medium concentration ice moving from the red towards the blue over the previous day. 

But why the alternating stripes?  Cloud effects?  (if so, that would mean my above 'suggestion' is wrong: nothing happening on the ground - just enjoy the pretty pictures.  Focus on the big picture.)
Because there are plenty of these "stretch marks" caused by openings in the pack storm after storm.
No cloud effect, just translation of the broken pack

ghoti

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Re: Home brew AMSR2 extent & area calculation
« Reply #3154 on: August 08, 2017, 11:35:04 PM »
Isn't the red/blue striping due to threshold effects? Broken up ice moving leads to a strip of area dropping below the 15% threshold showing red while the area this ice moved into bumps above the threshold and shows as blue.

greatdying2

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Re: Home brew AMSR2 extent & area calculation
« Reply #3155 on: August 09, 2017, 12:21:57 AM »
It's not cloud. The ridge can be seen in the ice on this Aug 4th image from WorldView. Could it be bands of thicker ice formed originally by ridging that are now moving? Similar patterns also appear in the areas that are melting out inside the ice perimeter.
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Re: Home brew AMSR2 extent & area calculation
« Reply #3156 on: August 09, 2017, 10:32:06 AM »
It's not cloud. The ridge can be seen in the ice on this Aug 4th image from WorldView. Could it be bands of thicker ice formed originally by ridging that are now moving? Similar patterns also appear in the areas that are melting out inside the ice perimeter.
My guess is it's a shadow of a contrail. I saw one crossing southern Greenland from an airplane and it really looked odd before I understood what it was..

Wipneus

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Re: Home brew AMSR2 extent & area calculation
« Reply #3157 on: August 09, 2017, 11:54:07 AM »
Some more of the same. In the CAA some serious work is done to clear a passage. Greenland Sea ice look pitiful, fast ice is breaking of to replace the sea ice.

Update 20170808.

Extent: -69.1 (+135k vs 2016, -95k vs 2015, -630k vs 2014, -435k vs 2013, +559k vs 2012)
Area: -71.7 (+251k vs 2016, +33k vs 2015, -635k vs 2014, -423k vs 2013, +679k vs 2012)
 
The details (in 1000 km2):


Extent:
   Central Arctic Basin       East Siberian Sea              Laptev Sea
                  -19.5                    -4.4                     0.0
               Kara Sea             Barents Sea           Greenland Sea
                   -8.5                    -0.8                   -11.0
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
                   -3.3                     0.0                    -1.4
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
                  -11.4                    -7.0                    -1.7
             Bering Sea          Sea of Okhotsk            Total Extent
                    0.0                     0.0                   -69.1

Area:
   Central Arctic Basin       East Siberian Sea              Laptev Sea
                  -65.8                    11.7                     7.3
               Kara Sea             Barents Sea           Greenland Sea
                   -6.8                    -1.3                    -2.4
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
                    2.1                     0.0                    -0.7
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
                   -3.7                   -12.0                    -0.3
             Bering Sea          Sea of Okhotsk              Total Area
                    0.0                     0.0                   -71.7


Delta map attached: red/blue means the concentration went below/over the 15% cut-off. Reddish/bluish means the concentration decreased/increased by more than 7%.

Details of the mentioned regions, click to enlarge.

Wipneus

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Re: Home brew AMSR2 extent & area calculation
« Reply #3158 on: August 09, 2017, 12:25:29 PM »
Comparative animation Arctic 2012/2017.

Click to start.

johnm33

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Re: Home brew AMSR2 extent & area calculation
« Reply #3159 on: August 09, 2017, 12:40:44 PM »
"But why the alternating stripes?  Cloud effects? "
Possibly wave effects, if the ice is small enough instead of bobbing up and down as the waves pass it 'surfs' forming windrows where it's caught by denser floes.[?]

CameraMan

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Re: Home brew AMSR2 extent & area calculation
« Reply #3160 on: August 10, 2017, 05:29:52 AM »
Comparative animation Arctic 2012/2017.

Interesting, thanks for that!  Rough impression, this year isn't so dispersed on the pacific side, but still thin.  Above CAA might be a bit better than 2012, but yikes, the Atlantic side looks awful.

Wipneus

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Re: Home brew AMSR2 extent & area calculation
« Reply #3161 on: August 10, 2017, 09:45:36 AM »
The 50k extent drop is mostly caused by the CAB's Beaufort/Chukchi front.  Almost no changes in area.

Update 20170809.

Extent: -53.4 (+108k vs 2016, -119k vs 2015, -615k vs 2014, -427k vs 2013, +626k vs 2012)
Area: -1.8 (+265k vs 2016, +3k vs 2015, -548k vs 2014, -349k vs 2013, +840k vs 2012)
 
The details (in 1000 km2):


Extent:
   Central Arctic Basin       East Siberian Sea              Laptev Sea
                  -40.4                    -0.2                     3.3
               Kara Sea             Barents Sea           Greenland Sea
                    0.2                    -1.6                    -6.0
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
                   -9.5                     0.0                    -0.4
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
                   11.3                    -7.1                    -3.0
             Bering Sea          Sea of Okhotsk            Total Extent
                    0.0                     0.0                   -53.4

Area:
   Central Arctic Basin       East Siberian Sea              Laptev Sea
                    2.7                    -4.1                     5.4
               Kara Sea             Barents Sea           Greenland Sea
                    3.7                    -1.3                    -1.2
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
                   -8.0                     0.0                    -1.5
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
                    2.3                     2.0                    -1.8
             Bering Sea          Sea of Okhotsk              Total Area
                    0.0                     0.0                    -1.8



Delta map attached: red/blue means the concentration went below/over the 15% cut-off. Reddish/bluish means the concentration decreased/increased by more than 7%.

The detail focuses on the Laptev region up to the pole. The big polynya in there was noticed before and also existed in 2012 as can be seen on yesterday's animation.
More material to discuss the concentration increase/decrease patterns.

Wipneus

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Re: Home brew AMSR2 extent & area calculation
« Reply #3162 on: August 11, 2017, 09:28:43 AM »
Ice still declines mostly on the Beaufort/Chukchi side.

Update 20170810.

Extent: -48.1 (+140k vs 2016, -94k vs 2015, -590k vs 2014, -420k vs 2013, +709k vs 2012)
Area: -29.4 (+268k vs 2016, +21k vs 2015, -555k vs 2014, -303k vs 2013, +873k vs 2012)

The details (in 1000 km2):


Extent:
   Central Arctic Basin       East Siberian Sea              Laptev Sea
                  -39.0                     5.0                    -8.5
               Kara Sea             Barents Sea           Greenland Sea
                    0.1                    -1.1                    -0.5
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
                   -2.2                     0.0                    -1.4
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
                    3.8                    -3.5                    -0.8
             Bering Sea          Sea of Okhotsk            Total Extent
                    0.0                     0.0                   -48.1

Area:
   Central Arctic Basin       East Siberian Sea              Laptev Sea
                   -6.8                     2.2                    -4.0
               Kara Sea             Barents Sea           Greenland Sea
                   -0.3                     1.4                     1.1
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
                   -1.4                     0.0                    -0.4
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
                   -3.3                   -17.3                    -0.5
             Bering Sea          Sea of Okhotsk              Total Area
                    0.0                     0.0                   -29.4



Delta map attached: red/blue means the concentration went below/over the 15% cut-off. Reddish/bluish means the concentration decreased/increased by more than 7%.


Wipneus

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Re: Home brew AMSR2 extent & area calculation
« Reply #3163 on: August 11, 2017, 09:31:35 AM »
The Beaufort side animated.

oren

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Re: Home brew AMSR2 extent & area calculation
« Reply #3164 on: August 11, 2017, 09:57:21 AM »
Very interesting. The Atlantic front and the CAA are very resistant this year.
In the animation, some distinct isolated ice shapes on the Chukchi front are winking out and coming back several times, probably rain from the storm making them too wet? Or obscured by clouds.

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Re: Home brew AMSR2 extent & area calculation
« Reply #3165 on: August 11, 2017, 10:36:19 AM »
In the animation, some distinct isolated ice shapes on the Chukchi front are winking out and coming back several times, probably rain from the storm making them too wet? Or obscured by clouds.

Maybe all of those reasons you mention.

Sensitivity to these distortions depends on the algorithm that is used to calculate concentration from passive radio measurements.

Attached is a Jaxa animation which uses the Bootstrap algorithm, which theoretically is much less sensitive to clouds/water vapor than the ASI method used by Uni Hamburg and Uni Bremen.

Event there some artifacts can be seen which should be caused be surface effects (e.g. rain/hail/sleet/snow).

The animation runs to the 9th August.

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Re: Home brew AMSR2 extent & area calculation
« Reply #3166 on: August 11, 2017, 10:20:55 PM »

Attached is a Jaxa animation which uses the Bootstrap algorithm, which theoretically is much less sensitive to clouds/water vapor than the ASI method used by Uni Hamburg and Uni Bremen.

Event there some artifacts can be seen which should be caused be surface effects (e.g. rain/hail/sleet/snow).

The animation runs to the 9th August.

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Wipneus

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Re: Home brew AMSR2 extent & area calculation
« Reply #3167 on: August 12, 2017, 05:49:16 PM »
Continuing losses in the same place. Area goes along.

Update 20170811.

Extent: -90.8 (+68k vs 2016, -57k vs 2015, -572k vs 2014, -445k vs 2013, +728k vs 2012)
Area: -97.6 (+134k vs 2016, +81k vs 2015, -608k vs 2014, -365k vs 2013, +801k vs 2012)

The details (in 1000 km2):


Extent:
   Central Arctic Basin       East Siberian Sea              Laptev Sea
                  -45.3                    -2.5                     2.6
               Kara Sea             Barents Sea           Greenland Sea
                   -2.8                    -3.7                    -7.2
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
                    1.2                     0.0                    -3.3
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
                  -19.2                   -10.8                     0.4
             Bering Sea          Sea of Okhotsk            Total Extent
                    0.0                     0.0                   -90.8

Area:
   Central Arctic Basin       East Siberian Sea              Laptev Sea
                  -82.5                    -1.4                     2.7
               Kara Sea             Barents Sea           Greenland Sea
                   -5.4                    -5.5                    -5.6
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
                    3.7                     0.0                    -1.5
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
                   -3.0                     0.8                     0.2
             Bering Sea          Sea of Okhotsk              Total Area
                    0.0                     0.0                   -97.6



Delta map attached: red/blue means the concentration went below/over the 15% cut-off. Reddish/bluish means the concentration decreased/increased by more than 7%.

Wipneus

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Re: Home brew AMSR2 extent & area calculation
« Reply #3168 on: August 12, 2017, 05:53:13 PM »
Animation of the CAA. Most of the holes in the garlic press are still closed, the main channel is open though and relieves the Basin from some of its ice.

Tor Bejnar

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Re: Home brew AMSR2 extent & area calculation
« Reply #3169 on: August 12, 2017, 06:55:41 PM »
For some ground-truthing, compare Wipneus' high-contrast map with O-Buoy 14's location and camera image (60% water?)
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magnamentis

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Re: Home brew AMSR2 extent & area calculation
« Reply #3170 on: August 12, 2017, 08:35:34 PM »
For some ground-truthing, compare Wipneus' high-contrast map with O-Buoy 14's location and camera image (60% water?)


beside the fact that you're right when it comes to the direct optical comparison it has to be mentioned that he many times pointed out that this images of his come with a somehow extremely increased contrast to show where things get "watery" only with that in mind those images can be interpreted correctly. they are artificial to point something out and not meant to be 1:1 readable as ice covered or ice-free which is why the comparison for the purpose of truth finding is not appropriate.

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uniquorn

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Re: Home brew AMSR2 extent & area calculation
« Reply #3171 on: August 12, 2017, 10:56:40 PM »
worldview yesterday

Wipneus

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Re: Home brew AMSR2 extent & area calculation
« Reply #3172 on: August 13, 2017, 05:41:37 PM »
Amazing drop in area today, mostly thanks to a regional century drop in the CAB.
Extent losses continue and are mostly in the CAB but seem less concentrated to the Beaufort side as in previous days.

Update 20170812.

Extent: -59.4 (+118k vs 2016, -7k vs 2015, -553k vs 2014, -523k vs 2013, +790k vs 2012)
Area: -167.2 (+131k vs 2016, +3k vs 2015, -729k vs 2014, -522k vs 2013, +678k vs 2012)

The details (in 1000 km2):

Extent:
   Central Arctic Basin       East Siberian Sea              Laptev Sea
                  -25.9                     1.0                    -7.9
               Kara Sea             Barents Sea           Greenland Sea
                   -3.2                    -5.1                    -5.6
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
                   -5.0                     0.0                    -2.4
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
                   -5.1                    -0.7                     0.5
             Bering Sea          Sea of Okhotsk            Total Extent
                    0.0                     0.0                   -59.4

Area:
   Central Arctic Basin       East Siberian Sea              Laptev Sea
                 -133.1                    -6.7                     3.0
               Kara Sea             Barents Sea           Greenland Sea
                    2.4                    -3.6                    -5.3
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
                   -6.7                     0.0                    -1.5
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
                   -4.6                   -11.3                     0.3
             Bering Sea          Sea of Okhotsk              Total Area
                    0.0                     0.0                  -167.2


Delta map attached: red/blue means the concentration went below/over the 15% cut-off. Reddish/bluish means the concentration decreased/increased by more than 7%.

Wipneus

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Re: Home brew AMSR2 extent & area calculation
« Reply #3173 on: August 13, 2017, 05:43:54 PM »
Arctic Basin animation.

Click to start.

Neven

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Re: Home brew AMSR2 extent & area calculation
« Reply #3174 on: August 13, 2017, 05:46:36 PM »
Amazing drop in area today, mostly thanks to a regional century drop in the CAB.

Cowabunga!

Not unexpected, though, as large patches of the ice pack look very iffy.

Second place should still be possible.
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FishOutofWater

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Re: Home brew AMSR2 extent & area calculation
« Reply #3175 on: August 13, 2017, 06:09:56 PM »
Curves that showed a compact ice pack are suddenly looking unreliable as large areas of thin ice melt out at once. What's shocking, like 2012, is how large areas of ice that looked solid are suddenly full of large areas of open water. It seems much to late to catch up with 2012, but it looks like a cliff is coming in ice extent.

This is a very interesting melt season that is testing all of our hypotheses about melt seasons.
« Last Edit: August 14, 2017, 06:32:50 PM by FishOutofWater »

greatdying2

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Re: Home brew AMSR2 extent & area calculation
« Reply #3176 on: August 13, 2017, 06:59:30 PM »
Arctic Basin animation.

Extremely interesting and useful animation -- thanks Wipneus.
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NeilT

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Re: Home brew AMSR2 extent & area calculation
« Reply #3177 on: August 13, 2017, 07:13:18 PM »
Arctic Basin animation

Correct me if I'm wrong but that looks like the ice pointing out towards Wrangel is being cut off and there is a huge polynia growing on the Atlantic side...
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Shared Humanity

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Re: Home brew AMSR2 extent & area calculation
« Reply #3178 on: August 13, 2017, 07:44:45 PM »
Looks like serious melting between Franz Josef and Svalbard.

Shared Humanity

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Re: Home brew AMSR2 extent & area calculation
« Reply #3179 on: August 13, 2017, 07:48:15 PM »
Arctic Basin animation

Correct me if I'm wrong but that looks like the ice pointing out towards Wrangel is being cut off...

That also occurred in 2012 and the cut off ice disappeared during the GAC but it occurred about 2 weeks earlier. We could very well have some lonely ice in the CAB near ESS as the melt season ends.

Sterks

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Re: Home brew AMSR2 extent & area calculation
« Reply #3180 on: August 13, 2017, 08:34:16 PM »
Arctic Basin animation

Correct me if I'm wrong but that looks like the ice pointing out towards Wrangel is being cut off...

That also occurred in 2012 and the cut off ice disappeared during the GAC but it occurred about 2 weeks earlier. We could very well have some lonely ice in the CAB near ESS as the melt season ends.
Last year too

greatdying2

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Re: Home brew AMSR2 extent & area calculation
« Reply #3181 on: August 13, 2017, 08:47:02 PM »
Looks like serious melting between Franz Josef and Svalbard.

Very much so. And it going to be hit by a storm over the next 2-3 days. I will be surprised if the whole Atlantic side isn't torn to pieces much like the Pacific side has been recently.
The Permian–Triassic extinction event, a.k.a. the Great Dying, occurred about 250 million years ago and is the most severe known extinction event. Up to 96% of all marine species and 70% of terrestrial vertebrate species became extinct; it is also the only known mass extinction of insects.

jdallen

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Re: Home brew AMSR2 extent & area calculation
« Reply #3182 on: August 13, 2017, 10:09:38 PM »
Amazing drop in area today, mostly thanks to a regional century drop in the CAB.
Not unexpected, though, as large patches of the ice pack look very iffy.

The region was full of sub-1.75 meter ice.  The bottom melt is now catching up with that.  I expect us to see continuing major SIA losses over the next few weeks for the same reason.

Curiously, because of the highly random distribution of fractured MYI, we may not see the same impact on extent.  We could see much of the basin at very low levels of concentration.
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Neven

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Re: Home brew AMSR2 extent & area calculation
« Reply #3183 on: August 13, 2017, 11:09:30 PM »
We should be seeing big drops for UH AMSR2 compactness, just like last year. What's interesting is that NSIDC compactness is still high and follows the 2013 trend line.

Maybe I should do another silly compactness map dividing NSIDC SIA by UH AMSR2 SIE...
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Neven

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Re: Home brew AMSR2 extent & area calculation
« Reply #3184 on: August 13, 2017, 11:58:38 PM »
We should be seeing big drops for UH AMSR2 compactness, just like last year. What's interesting is that NSIDC compactness is still high and follows the 2013 trend line.

Maybe I should do another silly compactness map dividing NSIDC SIA by UH AMSR2 SIE...


Okay, here's that silly graph, preceded by the NSIDC compactness graph. The silly graph is based on some silly idea I had last year, the idea behind it being:

I figured that if I used SIA at a low resolution, grid cells will be big and thus melt ponds and leads will have a larger impact on the numbers. If I then combine this with high-resolution extent that does the opposite - reduce the impact of melt ponds and open water between floes - I get a much more pronounced compactness ratio.
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Sterks

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Re: Home brew AMSR2 extent & area calculation
« Reply #3185 on: August 14, 2017, 12:21:33 AM »
We should be seeing big drops for UH AMSR2 compactness, just like last year. What's interesting is that NSIDC compactness is still high and follows the 2013 trend line.

Maybe I should do another silly compactness map dividing NSIDC SIA by UH AMSR2 SIE...
That's nice exploratory work Neven.
Personally I would also divide the NSIDC Area by the UH Area, to isolate and expose the effect of wet surface as much as possible. But that is matter for the next season, since that starts to be interesting in May and stop being so much by around these days of the season.

Neven

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Re: Home brew AMSR2 extent & area calculation
« Reply #3186 on: August 14, 2017, 12:50:12 AM »
In this case it's no longer really about melt ponds (as you say, that's more exciting in May and June), but rather about determining how much open water there is within the pack, compared to other years.

Simply to address one of the criticisms on conventional wisdom, sea ice extent in September to be precise. An ice pack full of holes can look healthy on an extent chart. Compactness gives a more nuanced view, although resolution clearly has to be high, as it looks like low-resolution data (NSIDC, 25 km grid) doesn't seem to be capturing all those zones of very low concentration ice. Yet.

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Rob Dekker

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Re: Home brew AMSR2 extent & area calculation
« Reply #3187 on: August 14, 2017, 08:41:17 AM »
Neven, your various measures of ice concentration are interesting, but I'm not sure if I understand the reasoning. For example :
I figured that if I used SIA at a low resolution, grid cells will be big and thus melt ponds and leads will have a larger impact on the numbers.

That is not necessarily the case. In fact, SIA numbers should be rather insensitive to resolution.
After all, if ice concentration is, say 30% over some area A of the Arctic, then regardless of the grid cell size, SIA will be calculated as 0.3*A.

'Extent' on the other hand DOES depend on the grid cell size. Especially on the ice edge.
So your NAPAE graph (NSIDC SIA / UH SIE) will be similar to (UH SIA / UH SIE) which is the 'blue' lines in Wipneus' ice concentration / compactness graph :

And indeed these 'blue' lines (with the black line being 2017) show concentration that is not as high as NSIDC's compactness graph.

The only thing I think you can conclude from that is that currently, there are fewer 'wide' (3km-25km) polynia than there were in prior years.
« Last Edit: August 14, 2017, 09:06:21 AM by Rob Dekker »

Neven

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Re: Home brew AMSR2 extent & area calculation
« Reply #3188 on: August 14, 2017, 05:53:14 PM »
That is not necessarily the case. In fact, SIA numbers should be rather insensitive to resolution.
After all, if ice concentration is, say 30% over some area A of the Arctic, then regardless of the grid cell size, SIA will be calculated as 0.3*A.

I hadn't thought of that. Thanks, Rob.

I shouldn't try to create fun hybrid data when I can't even wrap my head around the basic concept.  ;D
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Wipneus

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Re: Home brew AMSR2 extent & area calculation
« Reply #3189 on: August 14, 2017, 07:10:48 PM »
Half of yesterday's big drop in CAB area rebounded, casing a net area increase. The decline in extent was biggest in the CAA.

Update 20170813.

Extent: -46.6 (+139k vs 2016, -23k vs 2015, -524k vs 2014, -458k vs 2013, +828k vs 2012)
Area: +32.9 (+218k vs 2016, +59k vs 2015, -639k vs 2014, -458k vs 2013, +794k vs 2012)

The details (in 1000 km2):


Extent:
   Central Arctic Basin       East Siberian Sea              Laptev Sea
                   -6.2                    -1.3                   -14.6
               Kara Sea             Barents Sea           Greenland Sea
                    3.5                    -2.1                    10.6
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
                   -0.6                     0.0                    -0.8
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
                  -32.9                    -1.4                    -0.9
             Bering Sea          Sea of Okhotsk            Total Extent
                    0.0                     0.0                   -46.6

Area:
   Central Arctic Basin       East Siberian Sea              Laptev Sea
                   68.3                     2.8                   -13.1
               Kara Sea             Barents Sea           Greenland Sea
                    3.8                    -2.1                     6.1
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
                    2.3                     0.0                    -0.7
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
                  -39.7                     5.7                    -0.6
             Bering Sea          Sea of Okhotsk              Total Area
                    0.0                     0.0                    32.9


Delta map attached: red/blue means the concentration went below/over the 15% cut-off. Reddish/bluish means the concentration decreased/increased by more than 7%.

iceman

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Re: Home brew AMSR2 extent & area calculation
« Reply #3190 on: August 14, 2017, 08:11:43 PM »
Correct me if I'm wrong but that looks like the ice pointing out towards Wrangel is being cut off...

That also occurred in 2012 and the cut off ice disappeared during the GAC but it occurred about 2 weeks earlier. We could very well have some lonely ice in the CAB near ESS as the melt season ends.

GAC-12 seemed almost surgically precise in how it lopped off a huge expanse of ice.  This year the equivalent weak spot appears to be slightly east of the midpoint between Wrangel and the pole.  GFS forecasts a low in that locale around day 3-4, but likely not deep or persistent enough to cause a complete separation.

weatherdude88

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Re: Home brew AMSR2 extent & area calculation
« Reply #3191 on: August 15, 2017, 05:16:21 AM »
Significant area gains today (50K+). Extent looks to be a wash.


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Re: Home brew AMSR2 extent & area calculation
« Reply #3192 on: August 15, 2017, 08:49:49 AM »
Yes. Generalized under zero temperatures are the culprit.



However there is some agitation. In the forecast.

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Re: Home brew AMSR2 extent & area calculation
« Reply #3193 on: August 15, 2017, 06:00:15 PM »
CAB area increased nearly by a century, helping the total area increase. The CAA saw big drops both in extent and area.

Update 20170814.

Extent: -79.1 (+75k vs 2016, -72k vs 2015, -602k vs 2014, -535k vs 2013, +846k vs 2012)
Area: +25.4 (+257k vs 2016, +155k vs 2015, -648k vs 2014, -442k vs 2013, +882k vs 2012)
 
The details (in 1000 km2):


Extent:
   Central Arctic Basin       East Siberian Sea              Laptev Sea
                    9.6                    -7.1                    -4.8
               Kara Sea             Barents Sea           Greenland Sea
                   -2.8                    -4.2                    -8.3
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
                  -13.7                     0.0                    -0.3
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
                  -39.3                    -8.2                    -0.1
             Bering Sea          Sea of Okhotsk            Total Extent
                    0.0                     0.0                   -79.1

Area:
   Central Arctic Basin       East Siberian Sea              Laptev Sea
                   95.0                    10.2                    -5.9
               Kara Sea             Barents Sea           Greenland Sea
                   -7.6                    -2.4                    -5.2
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
                  -10.7                     0.0                     0.2
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
                  -43.9                    -4.3                     0.0
             Bering Sea          Sea of Okhotsk              Total Area
                    0.0                     0.0                    25.4


Delta map attached: red/blue means the concentration went below/over the 15% cut-off. Reddish/bluish means the concentration decreased/increased by more than 7%.

Wipneus

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Re: Home brew AMSR2 extent & area calculation
« Reply #3194 on: August 16, 2017, 09:24:15 AM »
There is still enough melting power to allow for centuries. Two days with increasing concentrations in the CAB is followed by a whopping area drop of -178k. CAB extent dropped (after rounding)  exactly one century. The drops are (again) on the Pacific front but also in the ESS/Laptev gap, but also the Atlantic front contributed.

Such days keep 2017 in the race for second place (in my limited data set).

Update 20170815.

Extent: -125.3 (-14k vs 2016, -187k vs 2015, -706k vs 2014, -624k vs 2013, +788k vs 2012)
Area: -184.2 (+111k vs 2016, -21k vs 2015, -814k vs 2014, -544k vs 2013, +694k vs 2012)
 
The details (in 1000 km2):


Extent:
   Central Arctic Basin       East Siberian Sea              Laptev Sea
                  -99.6                     5.6                    -1.9
               Kara Sea             Barents Sea           Greenland Sea
                  -10.0                    -2.8                    14.1
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
                   -5.4                     0.0                    -0.7
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
                  -11.6                   -12.3                    -0.8
             Bering Sea          Sea of Okhotsk            Total Extent
                    0.0                     0.0                  -125.3

Area:
   Central Arctic Basin       East Siberian Sea              Laptev Sea
                 -177.7                     5.0                    -5.5
               Kara Sea             Barents Sea           Greenland Sea
                   -7.9                    -0.7                    10.2
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
                   -2.9                     0.0                    -0.1
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
                   -1.1                    -3.4                    -0.1
             Bering Sea          Sea of Okhotsk              Total Area
                    0.0                     0.0                  -184.2



Delta map attached: red/blue means the concentration went below/over the 15% cut-off. Reddish/bluish means the concentration decreased/increased by more than 7%.

Wipneus

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Re: Home brew AMSR2 extent & area calculation
« Reply #3195 on: August 16, 2017, 09:27:41 AM »
Animation of the ESS/Laptev front. The "Laptev Eye" is distinctly triangular shaped.   

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Re: Home brew AMSR2 extent & area calculation
« Reply #3196 on: August 16, 2017, 09:47:57 AM »
Animation of the ESS/Laptev front. The "Laptev Eye" is distinctly triangular shaped.

Maybe you can add that Twilight Zone tune to your animation?  ;)
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RunningChristo

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Re: Home brew AMSR2 extent & area calculation
« Reply #3197 on: August 16, 2017, 11:35:46 AM »
The Laptev Triangle, the Arctic version of The Bermuda Triangle = where all the ice is "lost" 😉.
My fancy for ice & glaciers started in 1995:-).

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Re: Home brew AMSR2 extent & area calculation
« Reply #3198 on: August 16, 2017, 06:45:04 PM »
It looks to me like the area fluctuations at least in the Laptev bite are due to cloud. The extent drops that Wipneus started to detect there, inside the ice perimeter, should continue and accelerate -- there's a large area of low concentration ice...
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Re: Home brew AMSR2 extent & area calculation
« Reply #3199 on: August 16, 2017, 08:58:44 PM »
it appears as if the ESS part is about to break away from the 'central' ice pack. Would it be doomed then in the last 3/4 weeks we have left?