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Author Topic: Home brew AMSR2 extent & area calculation  (Read 1974465 times)

seaicesailor

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Re: Home brew AMSR2 extent & area calculation
« Reply #1650 on: June 18, 2015, 03:17:25 PM »

Further speculation, fun weather for the next few days. Hot in CAA Hudson and Laptev, over zero in much of the Arctic, and that storm ...

My 2c extent falls 300 k and area 700 k in one week, compactness starts to drop.

Definitely weather forecasts can be so misleading, especially for those who don't read them well. Such a short drop in area with the expectations the reports were creating, and actually I thought to put 800k due to that general increase of temperature.

I observe two things:
1-For some reasons, I find a tendency of models to overestimate temperatures on the 5-10 day range. Particularly GFS.
2-In this forum some of us tend to get over-excited if forecast look bad for ice, and expect drops that then don't come.

If next week there is not a drop of AT LEAST 1000k in area, I eat all those crow left-overs that people hadn't to eat in March. Same with extent AT LEAST 600k.
This means I don't expect to keep pace with 2012 but to stay close.

I shall eat all the leftovers. I shan't make more forecasts of this sort. B)

Edit: CT area dropped about 810K during past 7 days, flat days and monster drop included.
« Last Edit: June 18, 2015, 03:29:11 PM by seaicesailor »

johnm33

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Re: Home brew AMSR2 extent & area calculation
« Reply #1651 on: June 18, 2015, 04:00:51 PM »
Wipneus I get the same graph from both links above.

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Re: Home brew AMSR2 extent & area calculation
« Reply #1652 on: June 18, 2015, 04:13:07 PM »
Wipneus I get the same graph from both links above.

Fixed, thanks.

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Re: Home brew AMSR2 extent & area calculation
« Reply #1653 on: June 19, 2015, 11:44:11 AM »
Four days after the NSIDC and CT-area crash (posted by CT 2 days later, etc.), ASI AMSR2 by Uni Hamburg has a similar (but not as strong) drop in today's area data in combination with a very modest extent decline.

Regions are roughly the same: CAB bordering Beaufort, Chukchi and ESS as well as the CAA.

Since all common microwave based sea ice algorithms are equally affected by melt ponds, I think this means that serious melt ponding has now begun. The earlier drop in NSIDC concentration is then due to prior melt stages, wetting of snow, hard sea ice surface truning to a brine slush etc.

The details (in 1000 km2):

Update 20150618.

Extent: -22.3 (-150k vs 2014, -493k vs 2013, +340k vs 2012)
Area: -126.6 (-91k vs 2014, -212k vs 2013, +326k vs 2012)

Extent:
   Central Arctic Basin       East Siberian Sea              Laptev Sea
                    0.2                    -4.3                     4.0
               Kara Sea             Barents Sea           Greenland Sea
                  -16.7                    -1.5                     2.6
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
                   -5.0                     0.0                    -3.8
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
                    3.2                     4.1                    -4.4
             Bering Sea          Sea of Okhotsk            Total Extent
                    0.0                    -0.8                   -22.3

Area:
   Central Arctic Basin       East Siberian Sea              Laptev Sea
                  -30.1                   -28.9                     4.7
               Kara Sea             Barents Sea           Greenland Sea
                  -18.7                    -5.4                    -8.7
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
                  -10.9                     0.0                    -8.5
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
                  -15.1                    12.4                   -16.5
             Bering Sea          Sea of Okhotsk              Total Area
                    0.0                    -1.0                  -126.6


Wipneus

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Re: Home brew AMSR2 extent & area calculation
« Reply #1654 on: June 19, 2015, 02:18:05 PM »
The light feature in the East Siberian Sea has yesterday flipped from bright to dark in MODIS (TERRA, here the 7-2-1 composite).
So the channel is now of melting. Does that not contradict what has been said here before?

Peter Ellis

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Re: Home brew AMSR2 extent & area calculation
« Reply #1655 on: June 19, 2015, 02:55:15 PM »
Once the snow melts back fully, it may well revert to being darker than the surrounding ice.

Hear that galumphing sound? That's me doing a smug little dance in my chair.  Looks vaguely like a hippo on a spacehopper.

plinius

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Re: Home brew AMSR2 extent & area calculation
« Reply #1656 on: June 19, 2015, 04:07:53 PM »
The light feature in the East Siberian Sea has yesterday flipped from bright to dark in MODIS (TERRA, here the 7-2-1 composite).
So the channel is now of melting. Does that not contradict what has been said here before?

I'd have a tendency to say that this would point strongly in favour of the snow accumulation argument, but against the argument of more porous ice as the driving factor (the latter would have a serious trouble to explain the strong and sudden darkening).

Wipneus

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Re: Home brew AMSR2 extent & area calculation
« Reply #1657 on: June 19, 2015, 08:00:47 PM »
I have uploaded a Landsat image of the feature in the image of the day thread.

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Re: Home brew AMSR2 extent & area calculation
« Reply #1658 on: June 20, 2015, 06:58:17 AM »
Baffin Bay is noticeable slow this year to melt out. Here is a comparison with last year, it is also clear that Baffin contributes to the high compactness figures in 2015.

(click needed)

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Re: Home brew AMSR2 extent & area calculation
« Reply #1659 on: June 20, 2015, 07:36:05 AM »
The light feature in the East Siberian Sea has yesterday flipped from bright to dark in MODIS (TERRA, here the 7-2-1 composite).
So the channel is now of melting. Does that not contradict what has been said here before?

In some places the dark strip is not in the same spot as the light strip, but in others it is.  Put the tip of your mouse pointer on the top edge of the light strip in the middle and when it switches to light the mouse pointer switches to the bottom edge.
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Peter Ellis

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Re: Home brew AMSR2 extent & area calculation
« Reply #1660 on: June 20, 2015, 09:45:45 AM »
In some places the dark strip is not in the same spot as the light strip, but in others it is.

Look at the coastline - the pictures aren't taken from exactly the same spot.

Shared Humanity

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Re: Home brew AMSR2 extent & area calculation
« Reply #1661 on: June 20, 2015, 05:11:31 PM »
Baffin Bay and much of the eastern half of NA suffered from a brutally cold winter. The Saint Lawrence Sea had historic levels of ice. It has, as  expected, melted out. Is there any possibility that a portion of this large mass of thick sea ice will survive the melt season?

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Re: Home brew AMSR2 extent & area calculation
« Reply #1662 on: June 20, 2015, 07:30:25 PM »
In some places the dark strip is not in the same spot as the light strip, but in others it is.

Look at the coastline - the pictures aren't taken from exactly the same spot.

I made a mess using the WorldView software :-[ .   Here is a corrected animation.

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Re: Home brew AMSR2 extent & area calculation
« Reply #1663 on: June 20, 2015, 09:50:12 PM »
Baffin Bay and much of the eastern half of NA suffered from a brutally cold winter. The Saint Lawrence Sea had historic levels of ice. It has, as  expected, melted out. Is there any possibility that a portion of this large mass of thick sea ice will survive the melt season?

Nope. We have never seen ice survive the melt season in those areas in the satellite record.

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Re: Home brew AMSR2 extent & area calculation
« Reply #1664 on: June 25, 2015, 10:44:16 AM »
Update 20150624.
Changes from 20150617.

Extent: -363.5 (+148k vs 2014, -371k vs 2013, +397k vs 2012)
Area: -590.8 (+121k vs 2014, -398k vs 2013, +168k vs 2012)

This week total extent declined at an unremarkable rate a little over -50k/day. Compared with previous years 2015 is now only ahead of 2013, the year that only stated to seriously decline around this time.
Total area dropped much faster at a rate of nearly -85k/day, indicating some serious melt ponding. Quite normal and not enough to change the ranking between the years that I have comparable data of: only 2013 was slower.
Regionally most of the extent decline happened in regions not within of the Basin, only in the Chukchi Sea extent dropped significantly. Looking at the area figures shows that there is considerable melting activity especially in the Central Arctic Basin. The exception is Laptev that is showing small increases in area and extent.
In the Canadian Archipelago surface melting seems to be at the top of all regions. This is also shown by the ADS-NIPR thickness/melting map, showing darker shades of blue between the islands.
Temperatures and melting area are not anomalous, but the melting activity in the Arctic Basin and the expectation that the slowness in the peripheral regions Hudson and Baffin will have little influence on the final minimum are reasons to think  a strong second half of the melting season is still possible.

You will find the updated graphs in the top post

The details (in 1000 km2):


Extent:
   Central Arctic Basin       East Siberian Sea              Laptev Sea
                   14.5                    -7.4                     7.0
               Kara Sea             Barents Sea           Greenland Sea
                  -60.7                    -2.5                   -59.9
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
                  -75.0                     0.0                  -107.1
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
                  -18.3                     1.2                   -47.2
             Bering Sea          Sea of Okhotsk            Total Extent
                    0.0                    -8.1                  -363.5

Area:
   Central Arctic Basin       East Siberian Sea              Laptev Sea
                  -95.1                   -16.9                     4.6
               Kara Sea             Barents Sea           Greenland Sea
                  -56.8                   -18.1                  -106.9
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
                  -67.9                     0.0                  -106.3
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
                  -46.3                    -9.3                   -63.6
             Bering Sea          Sea of Okhotsk              Total Area
                    0.0                    -8.2                  -590.8


Wipneus

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Re: Home brew AMSR2 extent & area calculation
« Reply #1665 on: June 25, 2015, 10:59:54 AM »
The Canadian Archipelago is "torched" so badly that the ASI AMSR2 algorithm shows concentrations below 15% in places and thus "open water" (where I think is still solid ice). Look East of Melville Island.

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Re: Home brew AMSR2 extent & area calculation
« Reply #1666 on: June 26, 2015, 09:18:28 AM »
Fram export has stalled for the moment. The ice concentration in the Greenland Sea is dropping as a consequence.

(must click)

Steven

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Re: Home brew AMSR2 extent & area calculation
« Reply #1667 on: June 26, 2015, 06:17:42 PM »
The light feature in the East Siberian Sea has yesterday flipped from bright to dark in MODIS (TERRA, here the 7-2-1 composite).
So the channel is now of melting. Does that not contradict what has been said here before?


It has been cloudy there this week, but today there is an almost cloud-free view.  It seems that the color has flipped from dark to bright again:

From EOSDIS worldview, 26 June:

« Last Edit: June 26, 2015, 11:59:15 PM by Steven »

jdallen

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Re: Home brew AMSR2 extent & area calculation
« Reply #1668 on: June 26, 2015, 07:53:51 PM »
The light feature in the East Siberian Sea has yesterday flipped from bright to dark in MODIS (TERRA, here the 7-2-1 composite).
So the channel is now of melting. Does that not contradict what has been said here before?
It has been clouded there this week, but today there is an almost cloud-free view.  It seems that the color has flipped from dark to bright again:...

It is worth noting, the image indicates the fast ice in the ESS is now breaking up, which is in line with expectations I've had about coming dramatic melt.  That ice is extremely thin (generally less than 1.5M, with large stretches under 1M) and is being exposed to pretty extreme heat and significant insolation.
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Wipneus

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Re: Home brew AMSR2 extent & area calculation
« Reply #1669 on: June 27, 2015, 09:07:52 AM »
Canadian Archipelago keeps drawing attention. Here is a detail with the Nansen Sound between the islands Axel Heiberg and Ellesmere. The melt is extreme enough that the ASI AMSR2 algorithm sees near zero (certainly below 15%) ice concentration. Like most microwave sea ice concentration algorithms ASI does not distinguish between ocean and water on ice.
First image is from MODIS on Terra, second the color coded sea ice concentration from Uni Hamburg.

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Re: Home brew AMSR2 extent & area calculation
« Reply #1670 on: June 28, 2015, 08:22:28 AM »
Regional area and extent in the Beaufort is at comparable levels as last year. It looks quite different,  a less "solid" ice pack. Another difference is that this year the situation has not changed much for weeks while the ice in 2014 was in solid decline to last another few weeks.

(that animation will not start unless you click)

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Re: Home brew AMSR2 extent & area calculation
« Reply #1671 on: June 28, 2015, 09:56:25 AM »
Another difference is that this year the situation has not changed much for weeks

The fast ice along the north coast of Alaska visibly broke up earlier this year though. There was even a webcam and an IMB buoy to witness it!
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seaicesailor

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Re: Home brew AMSR2 extent & area calculation
« Reply #1672 on: June 28, 2015, 07:15:13 PM »
Regional area and extent in the Beaufort is at comparable levels as last year. It looks quite different,  a less "solid" ice pack. Another difference is that this year the situation has not changed much for weeks while the ice in 2014 was in solid decline to last another few weeks.

(that animation will not start unless you click)
Notice the huge floe breaking up in the last frames.
Very warmed up waters, these MYI blocks are probably doomed.

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Re: Home brew AMSR2 extent & area calculation
« Reply #1673 on: June 28, 2015, 08:15:35 PM »
The animation 
( 2015 )also shows the total breakdown of the sea ice over the Herald Shoal , the Taylor
columns have given up their influence for this season. Very early retreat there.

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Re: Home brew AMSR2 extent & area calculation
« Reply #1674 on: June 28, 2015, 10:30:26 PM »
The animation 
( 2015 )also shows the total breakdown of the sea ice over the Herald Shoal , the Taylor
columns have given up their influence for this season. Very early retreat there.
I believe you are correct.

I'd say looking at the animation, the blocks of MYI in the Beaufort not withstanding, conditions in both the Beaufort and Chukchi are far worse than 2014; the extent is very similar, but concentration and quality of the ice across both, well into the CAB is visibly worse off.
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Re: Home brew AMSR2 extent & area calculation
« Reply #1675 on: July 03, 2015, 09:27:56 AM »
Update 20150701.
Changes from 20150624.

Extent: -439.2 (+586k vs 2014, +49k vs 2013, +591k vs 2012)
Area: -339.5 (+405k vs 2014, +80k vs 2013, +461k vs 2012)

Declines in ice cover where moderate, extent about -60k/day and area under -50k/day. That is slower than the few previous years. Both area and extent are now above 2012, 2013 and 2014.
Looking regionally, it is now clear that Hudson and Baffin regions are late. Within the Basin it is just Laptev that is slow, but the declines there are just starting now for real.
The Jaxa AMSR2 thickness/melting maps are showing melting area and intensity well ahead of 2013/14. Thickness (although presumed to be unreliable because of the melting) has dropped substantially.
In summary for 2015 to be among the lowest minimum years it will have to start with an existing show soon. First the gap in the peripheral seas must be closed and second the momentum in the Basin must be built up and sustained well into August.
 
You will find the updated graphs in the top post

The details (in 1000 km2):


Extent:
   Central Arctic Basin       East Siberian Sea              Laptev Sea
                   -3.2                   -41.8                   -39.0
               Kara Sea             Barents Sea           Greenland Sea
                  -90.5                   -28.5                   -15.3
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
                  -65.3                     0.2                   -95.0
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
                   -3.4                   -13.8                   -36.0
             Bering Sea          Sea of Okhotsk            Total Extent
                    0.7                    -8.2                  -439.2

Area:
   Central Arctic Basin       East Siberian Sea              Laptev Sea
                   14.2                   -83.3                   -42.0
               Kara Sea             Barents Sea           Greenland Sea
                  -58.9                   -33.5                    -6.9
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
                  -61.4                     0.1                   -98.0
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
                   72.4                     7.1                   -44.0
             Bering Sea          Sea of Okhotsk              Total Area
                    0.4                    -5.8                  -339.5

« Last Edit: July 03, 2015, 09:38:34 AM by Wipneus »

Wipneus

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Re: Home brew AMSR2 extent & area calculation
« Reply #1676 on: July 03, 2015, 09:40:00 AM »
The ice edge in Chukchi is slowly giving way.

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Re: Home brew AMSR2 extent & area calculation
« Reply #1677 on: July 06, 2015, 11:29:44 PM »
 I would hardly say "Slowly"

 I totally agree with you saying the Hudson and Baffin are holding area high. If you add the difference of the two between this year and any of the last three years its around 400K Km/2

 So if the Hudson and Baffin were at 2012,13 or 14 levels total area looks a bit different.

Area (very approx): (+5k vs 2014, -320k vs 2013, +61k vs 2012)

  It's also a dead certainty they will melt out, I have a feeling this year may play catch up pretty quick.
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plinius

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Re: Home brew AMSR2 extent & area calculation
« Reply #1678 on: July 07, 2015, 12:04:32 AM »
I'd think we are still far behind 2012. But will with high probability beat 2014.

I would hardly say "Slowly"

 I totally agree with you saying the Hudson and Baffin are holding area high. If you add the difference of the two between this year and any of the last three years its around 400K Km/2

 So if the Hudson and Baffin were at 2012,13 or 14 levels total area looks a bit different.

Area (very approx): (+5k vs 2014, -320k vs 2013, +61k vs 2012)

  It's also a dead certainty they will melt out, I have a feeling this year may play catch up pretty quick.

Wipneus

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Re: Home brew AMSR2 extent & area calculation
« Reply #1679 on: July 07, 2015, 09:19:37 AM »
In Kara, the fast ice between Severnaya Zemlya and the Siberian coast is giving way. In 2013 I this ice was very suborn, not disappearing altogether.

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Re: Home brew AMSR2 extent & area calculation
« Reply #1680 on: July 07, 2015, 05:30:05 PM »
I would hardly say "Slowly"

 I totally agree with you saying the Hudson and Baffin are holding area high. If you add the difference of the two between this year and any of the last three years its around 400K Km/2

 So if the Hudson and Baffin were at 2012,13 or 14 levels total area looks a bit different.

Area (very approx): (+5k vs 2014, -320k vs 2013, +61k vs 2012)

  It's also a dead certainty they will melt out, I have a feeling this year may play catch up pretty quick.

Thank you for making this point; most of the difference between 2015 and 2012 can be explained by the ice in the Hudson and Baffin. 

Remove that, and the years look much closer. Toss in the additional remnant ice in the Kara, (which is on its way out), and the two years are in a dead heat... or possibly 2015 slightly ahead.

That said, there was much speculation last year (2014), to which this year bears much resemblance to mechanically, as to what would happen if we got warmer weather. 

It appears in 2015 we will find out.
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iceman

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Re: Home brew AMSR2 extent & area calculation
« Reply #1681 on: July 08, 2015, 04:42:24 PM »
In Kara, the fast ice between Severnaya Zemlya and the Siberian coast is giving way.

Yes, a week from now it will be almost completely gone from Severnaya Zemlya, with easterly winds blowing toward the open waters of the Kara.

Wipneus

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Re: Home brew AMSR2 extent & area calculation
« Reply #1682 on: July 10, 2015, 07:08:06 AM »
Due to other work I am not able to produce the weekly report with analysis. For this week I post just the numbers and the delta map. Please have a look yourself, watch the low concentration in the Chukchi area (not been seen since 2013, but on the other side of the Basin). Also have a look at the compaction graph: the AMSR2 product from Uni Hamburg and from Jaxa are nose diving, going well below 2012. Now that is a sure sign of extensive melt ponding!

BTW. today's CT-area estimates will have to come late as well.

Update 20150708.
Changes from 20150701.

Extent: -610.4 (+461k vs 2014, +335k vs 2013, +680k vs 2012)
Area: -890.1 (+65k vs 2014, -44k vs 2013, +376k vs 2012)

 
You will find the updated graphs in the top post

The details (in 1000 km2):


Extent:
   Central Arctic Basin       East Siberian Sea              Laptev Sea
                   -5.8                  -104.8                   -50.7
               Kara Sea             Barents Sea           Greenland Sea
                  -81.9                   -39.4                   -18.9
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
                  -75.9                     0.0                   -95.6
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
                  -21.1                   -10.6                  -103.1
             Bering Sea          Sea of Okhotsk            Total Extent
                    0.5                    -3.3                  -610.4

Area:
   Central Arctic Basin       East Siberian Sea              Laptev Sea
                 -176.3                  -112.5                   -65.7
               Kara Sea             Barents Sea           Greenland Sea
                  -82.3                   -17.4                   -35.3
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
                 -113.6                     0.0                   -77.3
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
                  -37.9                   -52.4                  -117.4
             Bering Sea          Sea of Okhotsk              Total Area
                    0.6                    -2.4                  -890.1

Wipneus

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Re: Home brew AMSR2 extent & area calculation
« Reply #1683 on: July 10, 2015, 07:24:09 AM »
Ice decline in the Baffin/Newfoundland Bay region is remarkable slow. The free floating ice will dsiappear soon it seems, but there is still quite a lot of concentrated ice against the coasts, especially in the south.

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Neven

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Re: Home brew AMSR2 extent & area calculation
« Reply #1684 on: July 10, 2015, 11:48:13 AM »
Quote
Also have a look at the compaction graph: the AMSR2 product from Uni Hamburg and from Jaxa are nose diving, going well below 2012. Now that is a sure sign of extensive melt ponding!
Wow, fascinating! Especially the Uni Hamburg dark blue trend line is stunning! No signs on CAPIE so far, although the 2015 trend line is very low here too:

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Wipneus

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Re: Home brew AMSR2 extent & area calculation
« Reply #1685 on: July 12, 2015, 03:35:46 PM »
Introducing two more graphs: extent and area of the restricted arctic basin (CAB+Beaufort+Chukchi+ESS+Laptev) for years 2012, 2013, 2014 and 2015.

This calculated  from three sea ice concentration data sets ( UH ASI AMSR2, Jaxa AMSR2 and NSIDC)

Greens are Jaxa, blue's are UH ASI AMSR2, reds are NSIDC), they are shifted u/d (and so have different y-axis's) for clarity.

The UH ASI line for 2012 is taken from the SSMIS data set. This data seems quite reasonably comparative to the AMSR2 data set but it adds another uncertainty so be extra careful here.



LINK



LINK
« Last Edit: July 13, 2015, 12:38:03 PM by Wipneus »

slow wing

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Re: Home brew AMSR2 extent & area calculation
« Reply #1686 on: July 12, 2015, 03:52:38 PM »
Very interesting! Thanks, Wipneus.

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Re: Home brew AMSR2 extent & area calculation
« Reply #1687 on: July 12, 2015, 08:45:27 PM »
Ice decline in the Baffin/Newfoundland Bay region is remarkable slow. The free floating ice will dsiappear soon it seems, but there is still quite a lot of concentrated ice against the coasts, especially in the south.

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it was a very cold and long winter in the eastern north america last winter.  i would assume that this would have affected hudson's bay and baffin bay
and so it goes

Tor Bejnar

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Re: Home brew AMSR2 extent & area calculation
« Reply #1688 on: July 12, 2015, 08:59:39 PM »
from The Nares Strait thread:
When early Hudson Bay melt put 2015 ahead of most (all?) other years, I recall someone (edit: Neven) wonder if extra early snow protected the ice from the grueling cold eastern North America experienced last NH winter.  I don't know what caused the early start, but I suspect there wasn't 'extra early snow' and that most of Hudson Bay and Baffin Bay were actually thicker than typical (compared to recent years), and the consequent extra ice is what has delayed their mid-season melt-out.  This may have also caused the Kane Basin ice bridge to be thicker and therefore more resilient.  I wonder if the ice bridge being across the 'middle' of Kane Basin (rather than across Smith Sound) means that water flowing under it is slower and less abrasive?

That ice bridge is sure slow to fully "give up the ghost"!
Arctic ice is healthy for children and other living things because "we cannot negotiate with the melting point of ice"

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Re: Home brew AMSR2 extent & area calculation
« Reply #1689 on: July 12, 2015, 09:53:54 PM »
Mati wrote:

Quote
it was a very cold and long winter in the eastern north america last winter.  i would assume that this would have affected hudson's bay and baffin bay

Good point. I hear from my friends there that there are still snow piles (very dark now) in some parking lots in the Boston area. If there's still snow in Boston in July (even piled snow), it's not too surprising that there is still some ice on waters hundreds of miles north. But it will all go in the next very few weeks, surely.
"A force de chercher de bonnes raisons, on en trouve; on les dit; et après on y tient, non pas tant parce qu'elles sont bonnes que pour ne pas se démentir." Choderlos de Laclos "You struggle to come up with some valid reasons, then cling to them, not because they're good, but just to not back down."

oren

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Re: Home brew AMSR2 extent & area calculation
« Reply #1690 on: July 12, 2015, 10:02:26 PM »
Thanks Wipneus! I find it interesting that the solid blue line in the area chart takes us to what seems like record territory, or at least lower than 2012.
I recommend/beg this chart as an "official" ongoing publication somewhere, maybe in the regional section?

Andreas T

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Re: Home brew AMSR2 extent & area calculation
« Reply #1691 on: July 12, 2015, 10:06:04 PM »
Mati wrote:

Quote
it was a very cold and long winter in the eastern north america last winter.  i would assume that this would have affected hudson's bay and baffin bay

Good point. I hear from my friends there that there are still snow piles (very dark now) in some parking lots in the Boston area. If there's still snow in Boston in July (even piled snow), it's not too surprising that there is still some ice on waters hundreds of miles north. But it will all go in the next very few weeks, surely.
my hunch is also that the early clearing of the northern Hudson bay may have been movement of ice southwards which compacted the ice in the south. Just like your snowpiles in the Boston parking lot last longer than the snow which was left in a thinner layer on the ground, this compacted ice i.e. pushed into piled up layers has less surface area per volume and takes longer to melt. As kids we spread the snowpiles we made clearing the pavement in front of our house back onto the road in the spring to accelerate their thawing and to get rid of them.

Bob Wallace

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Re: Home brew AMSR2 extent & area calculation
« Reply #1692 on: July 12, 2015, 10:14:02 PM »
Thanks Wipneus!

wili

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Re: Home brew AMSR2 extent & area calculation
« Reply #1693 on: July 12, 2015, 11:08:00 PM »
Andreas T wrote: "movement of ice southwards which compacted the ice in the south. Just like your snowpiles in the Boston parking lot"

Oooh, nice point. Hadn't thought about how parallel the situations actually may be!

I'd like to join Bob in also thanking Wipneus for all his excellent work here.
"A force de chercher de bonnes raisons, on en trouve; on les dit; et après on y tient, non pas tant parce qu'elles sont bonnes que pour ne pas se démentir." Choderlos de Laclos "You struggle to come up with some valid reasons, then cling to them, not because they're good, but just to not back down."

Wipneus

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Re: Home brew AMSR2 extent & area calculation
« Reply #1694 on: July 13, 2015, 12:49:02 PM »
Thanks Wipneus! I find it interesting that the solid blue line in the area chart takes us to what seems like record territory, or at least lower than 2012.


Oren, just for this I added the "caution 2012 is from SSMIS" warning. I have looked at it in some detail, concluded that it is probably real, but there is some additional uncertainty.

oren

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Re: Home brew AMSR2 extent & area calculation
« Reply #1695 on: July 13, 2015, 03:33:48 PM »
Thanks Wipneus! I find it interesting that the solid blue line in the area chart takes us to what seems like record territory, or at least lower than 2012.


Oren, just for this I added the "caution 2012 is from SSMIS" warning. I have looked at it in some detail, concluded that it is probably real, but there is some additional uncertainty.

ok, understood, thanks.

Wipneus

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Re: Home brew AMSR2 extent & area calculation
« Reply #1696 on: July 13, 2015, 03:41:32 PM »
Most of today's extent drop (-53k of -61k) happens in the ESS and Laptev regions.

wili

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Re: Home brew AMSR2 extent & area calculation
« Reply #1697 on: July 13, 2015, 03:44:09 PM »
Thanks, Wipneus. It looks like a "Laptev Wedge" is developing again, about to cross the 80 degrees north circle. Any estimates about when or whether it will reach 85? Or even the North Pole? Any idea why this feature should come up in about the same place two years in a row? Does anyone remember whether it was a feature before that?
"A force de chercher de bonnes raisons, on en trouve; on les dit; et après on y tient, non pas tant parce qu'elles sont bonnes que pour ne pas se démentir." Choderlos de Laclos "You struggle to come up with some valid reasons, then cling to them, not because they're good, but just to not back down."

plinius

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Re: Home brew AMSR2 extent & area calculation
« Reply #1698 on: July 13, 2015, 03:50:32 PM »
New siberian islands produce a general weakness in the ice, which usually propagates towards the  pole by the transarctic current. Depends a bit on the weather if and where it forms, but suppose it is mainly in years with strong transarctic drift during late winter/spring, and then the right wind patterns later on.
See e.g. here:
http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/ARCHIVE/20050824.jpg


oren

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Re: Home brew AMSR2 extent & area calculation
« Reply #1699 on: July 13, 2015, 03:59:03 PM »
Is there any impact of the warmer Lena river water discharging into the area?