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Jim Hunt

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Re: Home brew AMSR2 extent & area calculation
« Reply #1500 on: April 14, 2015, 10:12:17 AM »
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epiphyte

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Re: Home brew AMSR2 extent & area calculation
« Reply #1501 on: April 15, 2015, 01:09:07 AM »
Um... Does oil have a 90Ghz absorption peak, by any chance?

I tried to Google it, and got some hints that it might - but they were all in unreachable books/papers.

ktonine

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Re: Home brew AMSR2 extent & area calculation
« Reply #1502 on: April 15, 2015, 02:56:01 AM »
Um... Does oil have a 90Ghz absorption peak, by any chance?

I tried to Google it, and got some hints that it might - but they were all in unreachable books/papers.

You might decipher it from this paper: Measurement of Oil Thickness on Water from Aircraft


http://www.esrfunds.org/pdf/78.pdf

epiphyte

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Re: Home brew AMSR2 extent & area calculation
« Reply #1503 on: April 15, 2015, 05:50:58 AM »
Um... Does oil have a 90Ghz absorption peak, by any chance?

I tried to Google it, and got some hints that it might - but they were all in unreachable books/papers.

You might decipher it from this paper: Measurement of Oil Thickness on Water from Aircraft


http://www.esrfunds.org/pdf/78.pdf

If I'm reading it right, the paper looks at the interface between polar water at temps between 0 and 20C, and oil between 0.3 & 1mm thick - and finds huge differences in frequency response across that range... So doesn't shed much light on ice+oil :(

... still, it does go to the plausibility of the theory that some surface or near-surface contaminant might be responsible for the anomaly - & if that's the case, oil would certainly seem to be a candidate...
« Last Edit: April 15, 2015, 06:23:57 AM by epiphyte »

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Re: Home brew AMSR2 extent & area calculation
« Reply #1504 on: April 15, 2015, 01:59:41 PM »
My guess is it is not contamination but some sort of physical process that has created this. Could it be snowless ice?  Perhaps a couple of leads opened up (they seem to run parallel) and the snow melted adjacent to  the leads? The leads then closed and the feature is now  racing toward Fram.

Wipneus

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Re: Home brew AMSR2 extent & area calculation
« Reply #1505 on: April 16, 2015, 09:53:11 AM »
Update 20150415.
Changes from 20150408.

Extent: +9.8 (-173k vs 2014, -397k vs 2013, -608k vs 2012)
Area: -94.4 (-232k vs 2014, -498k vs 2013, -655k vs 2012)

The people from Uni Hamburg have been busy adjusting to the new versions of the AMSR2 level 1 data: version 2.0 on March 26 was succeeded by version 2.1 in days. Now all the data seem to have been reprocessed and  the daily supply restored.
In the last week there was only a small change in total extent, but a much larger drop in total area. Extent declined in the Barents and Kara regions, while on the Pacific side extents increased. Looking at the regional graphs, highest ice cover in the Barents Sea of recent years and lowest in the Bering Sea have come to an end.
The anomalous area declines took place in the Central Arctic and the Hudson Bay. Warmer air in these regions must at least have contributed even if the 2m temperatures are still below freezing everywhere. 

 
You will find the updated graphs in the top post

The details (in 1000 km2):


Extent:
   Central Arctic Basin       East Siberian Sea              Laptev Sea
                   -8.3                     1.0                    -0.2
               Kara Sea             Barents Sea           Greenland Sea
                  -37.7                   -45.4                    19.5
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
                   18.1                   -20.7                   -28.5
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
                   -3.9                     0.0                     5.9
             Bering Sea          Sea of Okhotsk            Total Extent
                   58.4                    51.6                     9.8

Area:
   Central Arctic Basin       East Siberian Sea              Laptev Sea
                  -47.6                     1.7                    -0.9
               Kara Sea             Barents Sea           Greenland Sea
                  -54.0                   -42.7                    10.2
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
                   -3.0                   -20.6                   -78.1
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
                  -10.7                     2.2                    16.9
             Bering Sea          Sea of Okhotsk              Total Area
                   78.1                    54.0                   -94.4


Wipneus

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Re: Home brew AMSR2 extent & area calculation
« Reply #1506 on: April 16, 2015, 09:54:49 AM »
The "torch" is on over the Hudson bay.

Wipneus

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Re: Home brew AMSR2 extent & area calculation
« Reply #1507 on: April 20, 2015, 08:49:52 AM »
Another "torch" is aiming at a large area in the Central Basin, ranging from the Fram Strait to the North Pole and beyond. One effect is that area has dropped much more than extent, not only measured by this ASI based sea ice concentration but also on that from Jaxa (that uses the Bootstrap algorithm).

slow wing

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Re: Home brew AMSR2 extent & area calculation
« Reply #1508 on: April 20, 2015, 09:21:25 AM »
Very interesting plot as always, thanks Wipneus. But can ice really 'torch' that quickly? Must be dispersion, no?

Wipneus

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Re: Home brew AMSR2 extent & area calculation
« Reply #1509 on: April 20, 2015, 09:45:01 AM »
No, this is not concentration dropping so quickly. However we have seen this more often in this time of year (last year it was spectacular in the Laptev region), so it will have to do something with the melting setting in.

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Re: Home brew AMSR2 extent & area calculation
« Reply #1510 on: April 20, 2015, 11:03:40 AM »
OK, very interesting! Thanks Wipneus

P-maker

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Re: Home brew AMSR2 extent & area calculation
« Reply #1511 on: April 20, 2015, 11:36:42 AM »
Wipneus,

Allow me to correct
 
Quote
”… it will have to do something with the melting setting in.”
According to various buoys and other information, air temperatures in the Central Arctic Basin are not yet above freezing, hence a better suggestion would be to call it sublimation. If you compare the amount of precipitable water in the atmosphere from this site: http://cci-reanalyzer.org/ , it is generally very dry and temperatures are rising over the basin.

One could suggest a signature of such a “torching” or “scorching” process being similar to the surface texture of the delicious Crème Brûlée (here is an example with goat cheese: http://www.chavrie.com/recipes/dessert/creme-brulee-with-chavrie-goat-cheese/ ).

Jim Hunt

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Re: Home brew AMSR2 extent & area calculation
« Reply #1512 on: April 20, 2015, 11:58:09 AM »
According to various buoys and other information, air temperatures in the Central Arctic Basin are not yet above freezing,

According to ice mass balance buoy 2015D air temperatures at the North Pole were briefly above the freezing point of sea water not so very long ago:

http://forum.arctic-sea-ice.net/index.php/topic,1149.msg50416.html#msg50416
« Last Edit: April 20, 2015, 01:17:35 PM by Jim Hunt »
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Re: Home brew AMSR2 extent & area calculation
« Reply #1513 on: April 20, 2015, 12:00:21 PM »
According to various buoys and other information, air temperatures in the Central Arctic Basin are not yet above freezing,

According to Iice mass balance buoy 2015D air temperatures at the North Pole were briefly above the freezing point of sea water not so very long ago:

http://forum.arctic-sea-ice.net/index.php/topic,1149.msg50416.html#msg50416

 :-[ I must admit to having some difficulty parsing the graph, could you explain?

Richard Rathbone

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Re: Home brew AMSR2 extent & area calculation
« Reply #1514 on: April 20, 2015, 12:26:55 PM »
Each line is a plot of temperature along a thermistor string with the low numbered thermistors being at the top.

The flat portion of the profile starting from the top (thermistors 1-5) is where the thermistors are in the air and the temperature of the air doesn't change much with height.

Similarly the flat portion at the bottom (thermistors 31-38) is where they are in the sea, and again there isn't much variation with height.

If both air and sea temperatures stayed constant, you'd see a constant slope in the ice in between (switching to a steeper constant slope in a snow layer if there was one present). The sea temperature does stay pretty much the same so you see the profiles from the different days overlay one another, but the air temperature doesn't so you see differences at the top end.

When the air temperature changes that change permeates into the ice fastest at the top and slower with depth, so you see a curve in the profile within the ice which is sharpest at the top.
.

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Re: Home brew AMSR2 extent & area calculation
« Reply #1515 on: April 20, 2015, 12:49:18 PM »
Each line is a plot of temperature along a thermistor string with the low numbered thermistors being at the top.

The flat portion of the profile starting from the top (thermistors 1-5) is where the thermistors are in the air and the temperature of the air doesn't change much with height.

Similarly the flat portion at the bottom (thermistors 31-38) is where they are in the sea, and again there isn't much variation with height.

If both air and sea temperatures stayed constant, you'd see a constant slope in the ice in between (switching to a steeper constant slope in a snow layer if there was one present). The sea temperature does stay pretty much the same so you see the profiles from the different days overlay one another, but the air temperature doesn't so you see differences at the top end.

When the air temperature changes that change permeates into the ice fastest at the top and slower with depth, so you see a curve in the profile within the ice which is sharpest at the top.
.

Much appreciated.

Jim Hunt

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Re: Home brew AMSR2 extent & area calculation
« Reply #1516 on: April 20, 2015, 03:35:51 PM »
I must admit to having some difficulty parsing the graph, could you explain?

Richard has covered the basics admirably. A somewhat more detailed explanation is available at:

http://GreatWhiteCon.info/resources/ice-mass-balance-buoys/
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Neven

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Re: Home brew AMSR2 extent & area calculation
« Reply #1517 on: April 20, 2015, 11:39:32 PM »
No, this is not concentration dropping so quickly. However we have seen this more often in this time of year (last year it was spectacular in the Laptev region), so it will have to do something with the melting setting in.

UB SIC shows the wipe as well, although I'm usually wary of these changing colours (click to see the animation):
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Re: Home brew AMSR2 extent & area calculation
« Reply #1518 on: April 21, 2015, 01:54:26 PM »
MODIS shows a large amount of cracking, and leads opening from a shattered Lincoln to Kara. Is this enough show a decrease in concentration?  The pole has also been sitting under a small storm cell for a few days, will this influence the satellite read?

Wipneus

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Re: Home brew AMSR2 extent & area calculation
« Reply #1519 on: April 22, 2015, 08:07:05 AM »
In the Beaufort region easterlies move the ice to the west, causing lots of cracks. Note the open water near Point Barrow, I will post a Sentinel image in the Arctic IOD thread.

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Re: Home brew AMSR2 extent & area calculation
« Reply #1520 on: April 23, 2015, 10:41:02 AM »
                  100.3                    68.0                   192.3
Update 20150422.
Changes from 20150415.

Extent: -94.1 (+137k vs 2014, -234k vs 2013, -602k vs 2012)
Area: -169.9 (+192k vs 2014, -385k vs 2013, -802k vs 2012)

Total extent and area declined with averages of -13k and -24k per day. Regionally the early melting season can be clearly recognized: most of the declines are in the Sea of Okhotsk and the Labrador Sea, with the Gulf of St. Lawrence already nearly ice free. The ice in the Barents Sea continues its retreat of the last few weeks, while in Kara and the Greenlans Sea ice extent and area grew.
Area declined more than extent this week, especially in the Central Basin. This was discussed in the 2015 melting thread but the reasons are not entirely clear especially since (T2m) temperatures are still below the freezing point.
 
You will find the updated graphs in the top post

The details (in 1000 km2):


Extent:
   Central Arctic Basin       East Siberian Sea              Laptev Sea
                   10.5                     0.0                   -12.7
               Kara Sea             Barents Sea           Greenland Sea
                   48.1                   -36.3                    41.7
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
                    1.9                    -0.1                    10.9
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
                   -8.2                    -9.2                    -5.0
             Bering Sea          Sea of Okhotsk            Total Extent
                   18.1                  -153.9                   -94.1

Area:
   Central Arctic Basin       East Siberian Sea              Laptev Sea
                  -71.3                    -0.3                   -17.9
               Kara Sea             Barents Sea           Greenland Sea
                   69.4                   -41.5                    -8.8
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
                   38.9                     4.3                    58.2
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
                   -2.7                   -20.6                   -12.5
             Bering Sea          Sea of Okhotsk              Total Area
                   -3.1                  -162.1                  -169.9


Wipneus

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Re: Home brew AMSR2 extent & area calculation
« Reply #1521 on: April 23, 2015, 10:44:29 AM »
Ice in the Sea of Okhotsk is saying good bye.

(click to animate)

Neven

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Re: Home brew AMSR2 extent & area calculation
« Reply #1522 on: April 23, 2015, 10:55:37 AM »
Bye-bye, Okhotsk ice! See you next year.  ;)
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Re: Home brew AMSR2 extent & area calculation
« Reply #1523 on: April 23, 2015, 11:48:27 AM »
Area declined more than extent this week, especially in the Central Basin. This was discussed in the 2015 melting thread but the reasons are not entirely clear especially since (T2m) temperatures are still below the freezing point.

I suspect what we are seeing is highly mobile ice that is simply being blown away when the conditions are right. Extent is holding up while area is going down. The pace of movement out of the Arctic Basin, and indeed the whole Arctic Circle, seems to be the critical  factor here. Lower density will mean lower albedo and faster warming. We may have lots of extent in warm water, that will result in a more rapid melt than would occur if the ice was more compact. 

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Wipneus

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Re: Home brew AMSR2 extent & area calculation
« Reply #1524 on: April 24, 2015, 07:56:42 AM »
Also in this animation of the sea ice in the Canadian Archipelago some mild "torching" is visible. The ice in the Amundsen Gulf is highly mobile, just like in 2014. On the other side the ice arch in the Lancaster Sound is located much deeper in the CAA than last year.
Also familiar is the great crack between the islands and the ice pack in the Central Basin that appears when the winds blow the ice to the north.

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Re: Home brew AMSR2 extent & area calculation
« Reply #1525 on: April 28, 2015, 06:59:55 AM »
Ice north of Greenland is moving towards the Fram Strait, not unlike what happened in 2014. The "son of goat" feature has about disappeared.

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Re: Home brew AMSR2 extent & area calculation
« Reply #1526 on: April 28, 2015, 07:52:37 AM »
Ice north of Greenland is moving towards the Fram Strait, not unlike what happened in 2014. The "son of goat" feature has about disappeared.
There are two or three pronounced dark striations in the 2015 sequence, running from the pole toward the Fram in a parallel SE -> southward curve. Are those real?

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Re: Home brew AMSR2 extent & area calculation
« Reply #1527 on: April 28, 2015, 08:44:45 AM »
Judging the persistence and the movement with the cracks I would say they are something "real", what I cannot say. Remember though that in these animations the contrast has been enhanced to make the ice movement better visible: those lines are present, but very subtle in the linear images.

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Re: Home brew AMSR2 extent & area calculation
« Reply #1528 on: April 30, 2015, 09:44:48 AM »
Update 20150429.
Changes from 20150422.

Extent: -410.4 (-171k vs 2014, -159k vs 2013, -465k vs 2012)
Area: -214.8 (-20k vs 2014, -93k vs 2013, -396k vs 2012)

Extent dropped nearly 60k/day last week. Area decline was more moderate, as the apparent low concentration know as "torching" in some parts of the Arctic was much reduced.
Regionally the declines where mostly in regions that where already in decline: Okhotsk and Bering on the Pacific side, the Baffin region and the Greenland Sea on the Atlantic. The ice in the Barents Sea did increase.
Looking at the new ADS (Arctic Data archive System) - Jaxa AMSR2 thickness&melting map (available on https://ads.nipr.ac.jp/vishop/vishop-monitor.html) almost all declines was ice that was already melting last week. The dry (not melting) ice extent did actually increase, as well as the apparent thickness. What this all means is not all that clear, but it is something else to watch this season.

(note: click that Jaxa image, it should animate)
 
You will find the updated graphs in the top post

The details (in 1000 km2):


Extent:
   Central Arctic Basin       East Siberian Sea              Laptev Sea
                   13.7                    -1.2                    14.2
               Kara Sea             Barents Sea           Greenland Sea
                   16.9                    77.5                   -33.0
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
                 -120.8                   -12.1                   -33.3
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
                    2.9                   -16.9                    -3.3
             Bering Sea          Sea of Okhotsk            Total Extent
                 -249.4                   -65.5                  -410.4

Area:
   Central Arctic Basin       East Siberian Sea              Laptev Sea
                  100.6                    -0.4                    25.8
               Kara Sea             Barents Sea           Greenland Sea
                    5.0                    62.8                    10.6
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
                 -121.1                   -11.4                   -19.4
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
                    2.5                   -12.9                    -0.9
             Bering Sea          Sea of Okhotsk              Total Area
                 -218.9                   -36.9                  -214.8


Wipneus

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Re: Home brew AMSR2 extent & area calculation
« Reply #1529 on: April 30, 2015, 10:13:42 AM »
Winds have created an impressive amount of open water near the Mackenzie Delta and the Amundsen Gulf.

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Re: Home brew AMSR2 extent & area calculation
« Reply #1530 on: April 30, 2015, 06:47:10 PM »
Impressive as always, Wipneus. I must say, I'm less alarmed by the open water than I am by the extensive fracturing propagating across the pack.  There is no coherence. There really isn't even a consistent pattern as the leads reorganize themselves, opening and closing around new arrangements of granular floes.
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Re: Home brew AMSR2 extent & area calculation
« Reply #1531 on: May 06, 2015, 11:10:07 AM »
Apologies in advance if this is the wrong forum, but it seems appropriate here. Also apologies for longish post.

Corrections for timecodes in cryosphere data

I have been using the cryosphere data (http://arctic.atmos.uiuc.edu/cryosphere/timeseries.anom.1979-2008) for a
couple of years for fun and no profit (as well as IJIS, PIOMAS and NSIDC).

At the time I set up an automated import into a database (PostgreSQL), and noted that the timecodes were not unique. I did not bother to look further then but just turned of the indexing on the timecode.

I have recently had some time on my hands and decided to have a closer look and after a few hours work found several inconsistencies and probable typos.

There are 366 data points for all years divisible by 4 and 365 for all others (except 1979 only had 364 values, 1979.0000 is missing). Note that 2000 is therefore considered a leap year. I use the term Y4 instead of leap year as a reminder that it is not strictly leap years.

Focusing first on the non-Y4 years I found the following inconsistencies (timecodes that are not round(d*365/10000) where d is the day of the year), some which appear to be obvious typos:
  • 1987.9253 -> 1987.9233
  • 2005.1088 -> 2005.1096
  • 2005.8650 -> 2005.8658
  • 2010.0928 -> 2010.0932
  • 2009.4274 -> 2009.4247 (duplicate code, only correct the first occurrence)
In addition, the block of values 2007.9315 - 2007.9808 (19 values) have been shifted 1 step (~0.0027) since the code 2007.9288 is missing and 2007.9808 is a duplicate.

The following will fix this:
  • for codes 2007.9342 - 2007.9780, set the code to the code on the previous line
  • change 2007.9315 -> 2007.9288 (missing time code)
  • change 2007.9808 -> 2007.9780 (first occurrence, duplicate entry).
This will make all non-Y4 years compact (365 values) and monotonically increasing by 1 day (~0.00274).

For the Y4 years there is more to do, I believe that approximately 3/4 of the year is one day off but this requires some more explanation.

I will post details on the Y4 years (which fixes all values with one glaring exception) if there is interest, either here or if I am pointed to some other appropriate forum.

Update: I have created a separate thread for this: http://forum.arctic-sea-ice.net/index.php/topic,1251.0.html
« Last Edit: May 06, 2015, 03:53:31 PM by plg »
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Pmt111500

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Re: Home brew AMSR2 extent & area calculation
« Reply #1532 on: May 06, 2015, 11:30:14 AM »
thanks plg, for reminding about this, those who have done this before and the new guys who might want to do this too. I solved this by calculating and replacing all the decimal dates separately for leap years and normal years, I figured 'the most I get is a day or two off the true value'. Could someone in the know tell, does the xxxx.0000 in CT today refer to the last day of year xxxx-1 or like it's supposed to be the 1st of Jan xxxx, if someone wants to be as accurate as possible? This just because there was some debate over this somewhere way back. Not that it matters much, the daily values swing so much over the years.

plg

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Re: Home brew AMSR2 extent & area calculation
« Reply #1533 on: May 06, 2015, 11:37:38 AM »
thanks plg, for reminding about this, those who have done this before and the new guys who might want to do this too. I solved this by calculating and replacing all the decimal dates separately for leap years and normal years, I figured 'the most I get is a day or two off the true value'. Could someone in the know tell, does the xxxx.0000 in CT today refer to the last day of year xxxx-1 or like it's supposed to be the 1st of Jan xxxx, if someone wants to be as accurate as possible? This just because there was some debate over this somewhere way back. Not that it matters much, the daily values swing so much over the years.
As far as I can tell xxxx.0000 is January first (day 1), but xxxx.9973 is Dec 31, not necessarily day 365. This means there are some tricks for Y4 years, mostly all dates after March 1 will be one day off and need to be corrected.

I can post more detail later.
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Re: Home brew AMSR2 extent & area calculation
« Reply #1534 on: May 06, 2015, 12:01:51 PM »
PLG, Could this discussion be moved into the Developers Corner in a new thread ("Issues with Analysis of Cryosphere Today data"?). Explaining the steps to normalise the dates would be useful for others I'm sure and will get lost in any of these regularly updated threads.

Also, I don't think this really fits here as this thread is regarding Wipneus' data calculations from AMSR2 data.

plg

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Re: Home brew AMSR2 extent & area calculation
« Reply #1535 on: May 06, 2015, 02:02:15 PM »
PLG, Could this discussion be moved into the Developers Corner in a new thread ("Issues with Analysis of Cryosphere Today data"?). Explaining the steps to normalise the dates would be useful for others I'm sure and will get lost in any of these regularly updated threads.

Also, I don't think this really fits here as this thread is regarding Wipneus' data calculations from AMSR2 data.
Thanks for the pointer, will do. (My tenuous rationale was that this thread was about calculations and area...)

Update: I have created a separate thread for this: http://forum.arctic-sea-ice.net/index.php/topic,1251.0.html
« Last Edit: May 06, 2015, 03:54:33 PM by plg »
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Re: Home brew AMSR2 extent & area calculation
« Reply #1536 on: May 07, 2015, 08:18:40 AM »
Update 20150506.
Changes from 20150429.

Extent: -348.3 (-177k vs 2014, -250k vs 2013, -331k vs 2012)
Area: -361.3 (-184k vs 2014, -122k vs 2013, -403k vs 2012)

This week saw strong declines in total extent and area with average rates of about 50 k/day.
Half of that are the Pacific regions Bering and Okhotsk. The other half on the Atlantic and the Hudson Bay regions. Ice in the Greenland Sea increased, due to ice exported through the Fram Strait. Jaxa's thickness and melt area map don't show an increase in melting area yet, actually a small decrease of about 100k. Further analysis of the Jaxa maps indicate that maximum volume was reached on May 2, volume levels are clearly below those of 2014 in contrast to the PIOMAS data. I will have more to say about the Jaxa thickness/melting data in a few days.
 
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                     0.7                    -8.0
               Kara Sea             Barents Sea           Greenland Sea
                  -25.2                   -23.9                    18.8
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
                  -89.0                   -13.3                   -53.9
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
                   -5.5                    15.8                    -1.4
             Bering Sea          Sea of Okhotsk            Total Extent
                  -84.0                   -96.8                  -348.3

Area:
   Central Arctic Basin       East Siberian Sea              Laptev Sea
                   22.6                    -5.6                   -29.3
               Kara Sea             Barents Sea           Greenland Sea
                  -30.6                    -5.5                    25.4
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
                  -96.3                    -9.3                   -83.1
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
                  -16.9                    13.7                    -5.6
             Bering Sea          Sea of Okhotsk              Total Area
                  -66.6                   -74.0                  -361.3


Wipneus

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Re: Home brew AMSR2 extent & area calculation
« Reply #1537 on: May 07, 2015, 08:24:52 AM »
Here are the Jaxa thickness maps discussed above.

(click you must)

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Re: Home brew AMSR2 extent & area calculation
« Reply #1538 on: May 07, 2015, 08:42:54 AM »
The hi-res AMSR2 sea ice concentration maps show considerable amounts of open water in the Kara Sea. Compare this with the NSIDC map (using the SSMIS instruments and Nasa Team algorithm) that just shows lower ice concentration in the area.

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Re: Home brew AMSR2 extent & area calculation
« Reply #1539 on: May 08, 2015, 06:52:04 AM »
While the ice in the Laptev Sea looks similar to last year, in the ESS there is a large bite of mobile ice  that was fast ice in 2014.

(click to animate)

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Re: Home brew AMSR2 extent & area calculation
« Reply #1540 on: May 08, 2015, 08:05:11 AM »
While the ice in the Laptev Sea looks similar to last year, in the ESS there is a large bite of mobile ice  that was fast ice in 2014.

(click to animate)
Implication:  There really isn't any fast ice any more...
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Re: Home brew AMSR2 extent & area calculation
« Reply #1541 on: May 10, 2015, 08:06:29 AM »
Time for a look at the Greenland Sea region, where the ice coming from the Arctic Basin is moving south.

(click to animate)

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Re: Home brew AMSR2 extent & area calculation
« Reply #1542 on: May 10, 2015, 01:56:35 PM »
What are the odds on that dark arc that emerges from the north and stretches to 2/3 of the way across Fram from Greenland is deep basal water breaking through Lomonosov ridge, with a distinct energetic signature causing it to flow as a coherent stream? Epiphyte asked the question upthread where there were 3-4 bands with a similar signature.

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Re: Home brew AMSR2 extent & area calculation
« Reply #1543 on: May 11, 2015, 04:02:10 AM »
Good call, John! The dark band doesn't appear to drift with the ice, so supporting the hypothesis it is associated with the geography of the sea bed. Fascinating!

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Re: Home brew AMSR2 extent & area calculation
« Reply #1544 on: May 12, 2015, 08:26:01 AM »
The Jaxa thickness/melting map shows the first melting area (not associated with the ice edge or big leads) in the Beaufort. The AMSR2 ASI sea ice concentration shows a "torching" at the same area (but not at a smaller but similar patch in Chukchi).




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Re: Home brew AMSR2 extent & area calculation
« Reply #1545 on: May 12, 2015, 09:30:02 AM »
The Jaxa thickness/melting map shows the first melting area (not associated with the ice edge or big leads) in the Beaufort.

Do you suppose JAXA have some sort of "automated melt pond detector"? Hamburg Uni used "an artificial neural network", but their data only goes up to 2011:

http://icdc.zmaw.de/1/daten/cryosphere/arctic-meltponds.html
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Re: Home brew AMSR2 extent & area calculation
« Reply #1546 on: May 12, 2015, 01:06:02 PM »
The Jaxa thickness/melting map shows the first melting area (not associated with the ice edge or big leads) in the Beaufort.

Do you suppose JAXA have some sort of "automated melt pond detector"? Hamburg Uni used "an artificial neural network", but their data only goes up to 2011:

http://icdc.zmaw.de/1/daten/cryosphere/arctic-meltponds.html

Yes, Jaxa uses of course microwave radiation (6GHz brightness seems to be the "main" channel) measured by AMSR2 while the Uni Hamburg method used MODIS visible wavelengths ( measuring the familiar "blue-ness" as it were).

I still intend to say more about the Jaxa thickness/melting data soon, it is something I intend to have a close look at this season.

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Re: Home brew AMSR2 extent & area calculation
« Reply #1547 on: May 13, 2015, 08:37:03 AM »

Wipneus, can you link legend for JAXA melting map, pls?

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Re: Home brew AMSR2 extent & area calculation
« Reply #1548 on: May 13, 2015, 08:50:44 AM »

Wipneus, can you link legend for JAXA melting map, pls?

Sure,  the Vishop monitor (previously known as Sea Ice Monitor): https://ads.nipr.ac.jp/vishop/vishop-monitor.html

Under "image select" choose Sea Ice Thickness.

(some people reported trouble with the site when using self-crippling browsing software preventing to see url's with "ads" in it. Make up your mind yourself how important that is.)


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Re: Home brew AMSR2 extent & area calculation
« Reply #1549 on: May 13, 2015, 09:15:00 AM »
Thanks, it works.