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Wipneus

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Re: 2017 sea ice area and extent data
« Reply #500 on: September 28, 2017, 06:13:58 PM »
Century extent drop or century extent increase?

Increase of course, corrected, thanks.

Wipneus

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Re: 2017 sea ice area and extent data
« Reply #501 on: September 28, 2017, 06:18:12 PM »
Yes, even more freezing: one and a half century area increase.

Regional Arctic Sea Ice Extent and Area calculated from NSIDC NASA Team concentration data
Date: 2017-09-27 12:00  Values in 1000 km^2

Extent (value, one day change, anomaly):
   Central Arctic Basin       East Siberian Sea              Laptev Sea
  3968.2  +37.6  -311.2    105.7  +17.4  -381.2    213.1   -0.6  -113.5
               Kara Sea             Barents Sea           Greenland Sea
    78.0   -7.2  -171.6      1.3   -1.3   -55.8    106.1   +4.4  -188.2
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
    76.1   +4.9    +0.8      0.0   +0.0    +0.0     11.6   +0.1    -9.9
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
   468.3   +9.0    -1.1     46.5   +5.7  -223.6      0.6   +0.0  -147.8
             Bering Sea          Sea of Okhotsk                   Lakes
     0.0   +0.0    -1.4      0.0   +0.0    +0.0    233.7  +86.9   +97.9
          Other regions       Total (ex. lakes)
     2.5   -0.0    +2.5   5078.2  +69.9 -1602.0

Area (value, one day change, anomaly):
   Central Arctic Basin       East Siberian Sea              Laptev Sea
  3110.2 +123.8  -528.5     45.3  +11.8  -292.2    136.9   +2.7   -72.6
               Kara Sea             Barents Sea           Greenland Sea
    38.2   +1.5  -113.8      0.4   -0.6   -27.7     54.7   +5.7  -128.1
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
    39.2   +1.9    -2.1      0.0   +0.0    +0.0      5.4   +0.3    -2.2
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
   272.8   +2.7   -29.2     20.2   +4.4  -162.2      0.4   +0.0   -97.7
             Bering Sea          Sea of Okhotsk                   Lakes
     0.0   +0.0    -0.3      0.0   +0.0    +0.0    106.7  +25.2   +48.9
          Other regions       Total (ex. lakes)
     0.5   -0.2    +0.5   3724.4 +154.0 -1456.0


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: 2017 sea ice area and extent data
« Reply #502 on: September 29, 2017, 07:01:51 PM »
Another day significant of concentration increases (area going up) . The ice edge advances towards the ESS (increasing extent mostly)..

Regional Arctic Sea Ice Extent and Area calculated from NSIDC NASA Team concentration data
Date: 2017-09-28 12:00  Values in 1000 km^2

Extent (value, one day change, anomaly):
   Central Arctic Basin       East Siberian Sea              Laptev Sea
  3992.3  +24.1  -291.7    130.9  +25.2  -363.4    227.4  +14.3  -106.9
               Kara Sea             Barents Sea           Greenland Sea
    73.0   -5.0  -180.8      0.0   -1.3   -58.6    105.0   -1.2  -198.3
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
    67.3   -8.8    -8.8      0.0   +0.0    +0.0     15.9   +4.4    -8.1
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
   463.0   -5.3   -18.2     53.5   +7.0  -222.1      0.6   +0.0  -149.9
             Bering Sea          Sea of Okhotsk                   Lakes
     0.0   +0.0    -1.8      0.0   +0.0    +0.0    234.8   +1.1   +94.7
          Other regions       Total (ex. lakes)
     2.5   +0.0    +2.5   5131.4  +53.2 -1606.0

Area (value, one day change, anomaly):
   Central Arctic Basin       East Siberian Sea              Laptev Sea
  3223.7 +113.5  -429.8     63.4  +18.1  -280.7    153.9  +17.0   -63.7
               Kara Sea             Barents Sea           Greenland Sea
    32.5   -5.7  -122.2      0.0   -0.4   -29.0     52.3   -2.4  -137.2
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
    39.5   +0.3    -2.9      0.0   +0.0    +0.0      7.4   +2.0    -0.9
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
   275.3   +2.4   -38.2     22.9   +2.7  -165.1      0.5   +0.0   -98.9
             Bering Sea          Sea of Okhotsk                   Lakes
     0.0   +0.0    -0.4      0.0   +0.0    +0.0    106.2   -0.5   +45.1
          Other regions       Total (ex. lakes)
     0.5   +0.0    +0.5   3871.9 +147.6 -1368.7


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%.

Wipneus

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Re: 2017 sea ice area and extent data
« Reply #503 on: September 30, 2017, 07:02:26 PM »
Area increase is much bigger than the gain in extent. That is helped by the CAA where area and extent go in opposite directions.

Regional Arctic Sea Ice Extent and Area calculated from NSIDC NASA Team concentration data
Date: 2017-09-29 12:00  Values in 1000 km^2

Extent (value, one day change, anomaly):
   Central Arctic Basin       East Siberian Sea              Laptev Sea
  3992.2   -0.1  -297.9    149.5  +18.6  -355.1    243.0  +15.6  -106.4
               Kara Sea             Barents Sea           Greenland Sea
    76.3   +3.2  -184.4      1.3   +1.3   -59.5     94.5  -10.5  -215.8
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
    70.4   +3.1    -7.0      0.0   +0.0    +0.0     16.4   +0.5    -9.8
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
   451.7  -11.3   -37.8     49.7   -3.8  -231.2      0.6   +0.0  -149.4
             Bering Sea          Sea of Okhotsk                   Lakes
     0.0   +0.0    -2.0      0.0   +0.0    +0.0    268.2  +33.4  +133.7
          Other regions       Total (ex. lakes)
     3.0   +0.5    +3.0   5148.5  +17.2 -1653.2

Area (value, one day change, anomaly):
   Central Arctic Basin       East Siberian Sea              Laptev Sea
  3261.1  +37.5  -415.4     78.7  +15.3  -274.2    167.7  +13.8   -60.5
               Kara Sea             Barents Sea           Greenland Sea
    32.5   -0.0  -126.4      0.4   +0.4   -29.7     45.0   -7.3  -152.5
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
    40.2   +0.7    -3.2      0.0   +0.0    +0.0      7.3   -0.2    -2.0
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
   295.4  +20.2   -26.6     19.5   -3.4  -174.5      0.4   -0.0   -99.0
             Bering Sea          Sea of Okhotsk                   Lakes
     0.0   +0.0    -0.5      0.0   +0.0    +0.0    117.6  +11.4   +60.6
          Other regions       Total (ex. lakes)
     0.6   +0.1    +0.6   3949.0  +77.0 -1363.9


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%.

Wipneus

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Re: 2017 sea ice area and extent data
« Reply #504 on: October 01, 2017, 07:33:03 PM »
Refreezing continues, this time half of it in the CAA.

First of October means that I stop with daily reports on extent and area based on NSIDC NT sea ice concentration. During the freezing season I will occasionally report and/or post updated graphs.

Regional Arctic Sea Ice Extent and Area calculated from NSIDC NASA Team concentration data
Date: 2017-09-30 12:00  Values in 1000 km^2

Extent (value, one day change, anomaly):
   Central Arctic Basin       East Siberian Sea              Laptev Sea
  3996.8   +4.6  -302.1    170.1  +20.6  -346.7    248.8   +5.8  -112.7
               Kara Sea             Barents Sea           Greenland Sea
    82.7   +6.4  -180.4      1.3   -0.0   -79.3     95.7   +1.3  -217.9
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
    69.8   -0.6   -14.9      0.0   +0.0    +0.0     31.7  +15.3    -4.9
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
   490.3  +38.6   -13.1     47.1   -2.6  -241.7      1.2   +0.6  -155.4
             Bering Sea          Sea of Okhotsk                   Lakes
     0.0   +0.0   -16.5      0.0   +0.0   -41.4    239.3  -29.0  +106.7
          Other regions       Total (ex. lakes)
     1.5   -1.5    +1.5   5237.1  +88.5 -1725.5

Area (value, one day change, anomaly):
   Central Arctic Basin       East Siberian Sea              Laptev Sea
  3261.0   -0.1  -438.2     94.1  +15.5  -269.7    159.3   -8.4   -79.2
               Kara Sea             Barents Sea           Greenland Sea
    36.5   +4.0  -124.7      0.3   -0.1   -39.6     45.5   +0.5  -152.8
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
    40.8   +0.5    -7.0      0.0   +0.0    +0.0     10.4   +3.1    -1.8
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
   325.3  +29.9    -5.8     19.0   -0.5  -180.3      0.9   +0.4  -101.0
             Bering Sea          Sea of Okhotsk                   Lakes
     0.0   +0.0    -4.4      0.0   +0.0   -13.8     96.3  -21.3   +40.8
          Other regions       Total (ex. lakes)
     0.3   -0.3    +0.3   3993.4  +44.4 -1418.0


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%.

Jim Pettit

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Re: 2017 sea ice area and extent data
« Reply #505 on: October 03, 2017, 02:14:51 PM »
JAXA Sea Ice Extent:

5,140,248 km2(October 02, 2017)up 48,036 km2
« Last Edit: October 04, 2017, 01:40:02 PM by Jim Pettit »

Jim Pettit

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Re: 2017 sea ice area and extent data
« Reply #506 on: October 04, 2017, 01:39:47 PM »
JAXA Sea Ice Extent:

5,187,695 km2(October 03, 2017)up 47,447 km2
« Last Edit: October 05, 2017, 02:55:46 PM by Jim Pettit »

Shared Humanity

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Re: 2017 sea ice area and extent data
« Reply #507 on: October 04, 2017, 02:09:15 PM »
A slow but steady increase in SIE, indistinguishable from the bulk of years on the graph.

Cato

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Re: 2017 sea ice area and extent data
« Reply #508 on: October 05, 2017, 09:28:54 AM »
Hi everybody, nice to join you here. Well done Neven! :)

Just one question: is Jim updating JAXA data on a daily basis, or is this left to the initiative of anyone in a "common effort" as proposed in the previous thread, same subject?

Jim Pettit

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Re: 2017 sea ice area and extent data
« Reply #509 on: October 05, 2017, 01:20:34 PM »
Just one question: is Jim updating JAXA data on a daily basis, or is this left to the initiative of anyone in a "common effort" as proposed in the previous thread, same subject?

I *do* update everyday--well, almost--as I've been doing for a number of years. But I'm just a lowly laborer in the vineyard toiling to keep Espen's simple but useful graph alive, and as such make no claim of sole possession. So far as I know, his graph--as with most others here--is terra nullius.

oren

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Re: 2017 sea ice area and extent data
« Reply #510 on: October 05, 2017, 01:38:54 PM »
Here's the chart from Jim's wonderful site.
Jim - would it be possible for you to add the daily extent number as a text label on the graph? Then it would be much easier to post the number and the calculable daily change as well as the chart from a single web source.

5,287,762 km2, up a whopping 91,097 km2, and 6th lowest for the date.
« Last Edit: October 05, 2017, 01:44:50 PM by oren »

Cato

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Re: 2017 sea ice area and extent data
« Reply #511 on: October 05, 2017, 01:44:16 PM »
Thanks Jim  ;)

Jim Pettit

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Re: 2017 sea ice area and extent data
« Reply #512 on: October 05, 2017, 02:56:01 PM »
JAXA Sea Ice Extent:

5,278,792 km2(October 04, 2017)up 91,097 km2
« Last Edit: October 06, 2017, 09:57:38 PM by Jim Pettit »

Shared Humanity

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Re: 2017 sea ice area and extent data
« Reply #513 on: October 05, 2017, 04:59:38 PM »
Just one question: is Jim updating JAXA data on a daily basis, or is this left to the initiative of anyone in a "common effort" as proposed in the previous thread, same subject?

I *do* update everyday--well, almost--as I've been doing for a number of years. But I'm just a lowly laborer in the vineyard toiling to keep Espen's simple but useful graph alive, and as such make no claim of sole possession. So far as I know, his graph--as with most others here--is terra nullius.

Hardly a lowly laborer in the vineyard.

If true, that makes me a Rotylenchulus, a genus of nematodes infesting that same vineyard.

Jim Pettit

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Re: 2017 sea ice area and extent data
« Reply #514 on: October 06, 2017, 10:08:28 PM »
Jim - would it be possible for you to add the daily extent number as a text label on the graph? Then it would be much easier to post the number and the calculable daily change as well as the chart from a single web source.

Done. I placed the pertinent data in the lower right corner of the image itself.


« Last Edit: October 07, 2017, 03:31:15 PM by Jim Pettit »

Shared Humanity

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Re: 2017 sea ice area and extent data
« Reply #515 on: October 06, 2017, 10:27:49 PM »
The pace of the freeze is unremarkable, difficult to distinguish from the other years charted.

Cato

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Re: 2017 sea ice area and extent data
« Reply #516 on: October 07, 2017, 08:35:39 AM »
+ 156,000!?  :o

binntho

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Re: 2017 sea ice area and extent data
« Reply #517 on: October 07, 2017, 09:04:45 AM »
JAXA Sea Ice Extent:
Done. I placed the pertinent data in the lower right corner of the image itself.
Jim, thanks for your work - but it's a bit of a bother to have to open the image in a separate window to see the lower right corner ...

oren

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Re: 2017 sea ice area and extent data
« Reply #518 on: October 07, 2017, 09:10:22 AM »
Jim - thank you for the change - and for the whole thing. (I think there's a bug in the sign though, the text should say up from previous, not down)
Binntho, the image should be saved and then uploaded, otherwise it's a cached copy. When it's uploaded you don't need to click it.

Edit: there's still the issue of size, as the uploaded image is beyond forum limits it is only partially shown (unless clicked), and the new text is half-hidden. If the text can be moved more to the left it will be a great help.

Edit 2: Neven, as the IJIS thread was bolded, I think this thread can be bolded as well.
« Last Edit: October 07, 2017, 09:28:27 AM by oren »

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Re: 2017 sea ice area and extent data
« Reply #519 on: October 07, 2017, 03:53:16 PM »
Jim - thank you for the change - and for the whole thing. (I think there's a bug in the sign though, the text should say up from previous, not down)
Thanks. The error was mine, and has been corrected for all future versions.

Jim, thanks for your work - but it's a bit of a bother to have to open the image in a separate window to see the lower right corner ...
Edit: there's still the issue of size, as the uploaded image is beyond forum limits it is only partially shown (unless clicked), and the new text is half-hidden. If the text can be moved more to the left it will be a great help.

The algorithms I use to update and upload my many graphs use an image resizing component to optimize the resolution and standardize the width of those images for presentation on my graphs page. The ASIF automatically sets the width of most images to 580px, but there's no default "max-width" attribute set, so sometimes images do appear here at full size, meaning you have to scroll over or click to see the whole thing. I'll talk to Neven about adding that attribute to the site's CSS sheet, which should end that problem.

I realize clicking on a particular image to see the latest non-cached version in the correct size is onerous, but I'm loathe to change all the algorithms at this time, so I won't have my feelings hurt if someone else wishes to try a different approach.
« Last Edit: October 08, 2017, 01:59:22 PM by Jim Pettit »

Wipneus

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Re: 2017 sea ice area and extent data
« Reply #520 on: October 07, 2017, 05:24:47 PM »
NSIDC extent and area graphs.

Shared Humanity

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Re: 2017 sea ice area and extent data
« Reply #521 on: October 07, 2017, 07:03:16 PM »
The graphs are perfect. Don't change a thing.

Neven

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Re: 2017 sea ice area and extent data
« Reply #522 on: October 08, 2017, 02:45:26 PM »
+123K followed by +155K for JAXA. Quite the increase, but far from abnormal. 2015 had +213K and +243K in a row. 2012 even had +289K and +252K later in the month, which makes sense, given how low it was.

Nevertheless, 2017 doesn't seem to be following 2016 as of yet.
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Pavel

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Re: 2017 sea ice area and extent data
« Reply #523 on: October 08, 2017, 07:12:55 PM »
The 2017 November and December extent could be low or record low due to warm Chukchi\ESS and Hudson Bay. The lowest annual maximum is also quite possible because of warm Sea of Okhotsk. Of course it may quickly lose its heat but it also mean more open water heat flux

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Re: 2017 sea ice area and extent data
« Reply #524 on: October 09, 2017, 12:02:27 AM »
Pavel you got a point here, but on the other hand surface sea temperature anomalies tend to decrease quickly if weather conditions are cold and windy. Anomalies are there, and are big, but the real driver in my humble opinion is...weather.

In the next days a thermal HP will be settling over the CAB and heat loss through radiation will increase massively as a result. It also looks like the HP pulsation in the Pacific won't be able to push warm air from the ocean into the Arctic. Strong winds will be blowing over Chuckhi and Bering, and I expect a quick reduction of positive anomalies up there. Models are changing a lot from run to run,  but based on today's maps I'm fairly optimistic for the next few days, while of course I can't make any sensible forecast for the whole winter. I guess it's just a wait-and-see pattern, as usual ;)

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Re: 2017 sea ice area and extent data
« Reply #525 on: October 09, 2017, 05:32:51 PM »
5.72 Mkmq vs. 5.59 Mkmq = +130,000 kmq ca.

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Re: 2017 sea ice area and extent data
« Reply #526 on: October 09, 2017, 10:49:00 PM »
The last few days have been very specific, separating 2017 from 2016 and the "low years" and sticking it squarely with (the low end of) the "pack".
Added with the DMI 80N chart dipping much below 2016 for the same date, my gut feeling is this winter refreeze will be stronger than the previous one.

Pavel

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Re: 2017 sea ice area and extent data
« Reply #527 on: October 09, 2017, 11:46:05 PM »
Last season it had a relatively cold February and especially a cold and snowy spring. The season is long and the 2016-like spring may be worse than the 2016-like autumn. So we just need to wait and see despite the fact it becomes unremarkable

Cato

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Re: 2017 sea ice area and extent data
« Reply #528 on: October 11, 2017, 02:24:38 PM »
Temperature anomalies over Chuckchi and Bering are quickly decreasing and if the synoptic charts are confirmed, in the next 7-10 days a major extension increase could be achieved in the mentioned areas and over ESS due to dispersion and quite lower temperatures.

In the meantime the ESS and Baffin Sea anomalies have been replaced with average or even lower than average temperatures. Ice surface temperatures are lower than -20C over a significant area between the CAB and the northern side of CAA, thus contributing to ice thickness increase. This ice surface cooling will be further enhanced due to the thermal HP which is forming over the CAB and will have a significant impact over weather conditions for the whole Arctic in the next days.

Ok nothing really unusual up there: it's October and all of this is normal. The problem is, what used to be "normal" is now a breaking news considering the status of the Arctic, but I'll take it anyway as a good news for the ice, and nothing more than that. As long as it lasts...

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Re: 2017 sea ice area and extent data
« Reply #529 on: October 12, 2017, 12:39:08 PM »
Temperature anomalies over Chuckchi and Bering are quickly decreasing and if the synoptic charts are confirmed, in the next 7-10 days a major extension increase could be achieved in the mentioned areas and over ESS due to dispersion and quite lower temperatures.

In the meantime the ESS and Baffin Sea anomalies have been replaced with average or even lower than average temperatures. Ice surface temperatures are lower than -20C over a significant area between the CAB and the northern side of CAA, thus contributing to ice thickness increase. This ice surface cooling will be further enhanced due to the thermal HP which is forming over the CAB and will have a significant impact over weather conditions for the whole Arctic in the next days.

Ok nothing really unusual up there: it's October and all of this is normal. The problem is, what used to be "normal" is now a breaking news considering the status of the Arctic, but I'll take it anyway as a good news for the ice, and nothing more than that. As long as it lasts...

FWIW, the 10-year average daily SIE increase from now through the end of the month has been 119k; in fact, the third week of October has historically seen the largest daily increases of the year, with a 10-year average of 136k. So if 2017 starts seeing sustained growth larger than that, I'll agree that something fundamentally wacky is going on. But so far, at least, growth since minimum has been right in line with normal, and the last two days have seen fairly sluggish growth.

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Re: 2017 sea ice area and extent data
« Reply #530 on: October 12, 2017, 01:17:06 PM »
JAXA Sea Ice Extent:
Jim, your post shows the graph updated only until Oct 6.
« Last Edit: October 12, 2017, 02:01:28 PM by Sterks »

A-Team

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Re: 2017 sea ice area and extent data
« Reply #531 on: October 12, 2017, 01:29:02 PM »
Why speculate when the forecast is just a click away?

Technical note: to give the palette 'more room' to distinguish thinner ice classes (the topic), ice thicker than 0.5 m is all lumped into a single terminal color. It just takes an extra click to produce a second animation that colored all ice thickness classes equally. Done in Panoply here, online palette squeezing is familiar from Worldview for image enhancement. The latter does not currently retain that in its animation tool however.
« Last Edit: October 12, 2017, 04:27:42 PM by A-Team »

Cato

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Re: 2017 sea ice area and extent data
« Reply #532 on: October 12, 2017, 01:47:23 PM »
Because confirmation bias are stronger than anything else, including laziness ;D

Personally I prefer to make my synoptic analyses and test them against reality than just watching a simulation. But I get your point: that map is simply fantastic!! :)

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Re: 2017 sea ice area and extent data
« Reply #533 on: October 12, 2017, 01:51:42 PM »
FWIW, the 10-year average daily SIE increase from now through the end of the month has been 119k; in fact, the third week of October has historically seen the largest daily increases of the year, with a 10-year average of 136k. So if 2017 starts seeing sustained growth larger than that, I'll agree that something fundamentally wacky is going on. But so far, at least, growth since minimum has been right in line with normal, and the last two days have seen fairly sluggish growth.
[/quote]

Thanks Jim, fully agree with you: the normal sounds unusual to me just because I've got used to expect the worst about arctic ice...

Sterks

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Re: 2017 sea ice area and extent data
« Reply #534 on: October 12, 2017, 02:09:36 PM »
Why speculate when the forecast is just a click away?
It's really cool but how do we quantify forecasted area or extent? Perhaps you have a tool for that?
Thanks for this work btw

A-Team

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Re: 2017 sea ice area and extent data
« Reply #535 on: October 12, 2017, 06:07:59 PM »
RASM-ESRL is a sophisticated physics-based computation at rather high spatial and temporal resolution; it is not a simulation.

To extend past the initial state, RASM-ESRL uses a full suite of satellite inputs such as AMSR2 sea ice concentration, separate forecasts for ice and air temperatures and movement; water temperatures, salinity and currents, and so forth.

Like ECMWF, RASM-ESRL makes testable predictions about near-term future conditions but is farther-reaching in its suite of meteorological, surface ice and oceanographic outputs.

While its predictions won't be a perfect match to subsequent observational data, it is pure fantasy to think one can adequately intuit future developments in Arctic Ocean ice by navel-gazing at weather charts, not with ~49 variables in play. Better mousetraps were built decades ago. And this one is free and just a click away.

My interest is whether RASM-ESRL can be improved. That won't happen to any extent through better meteorological forecasts because those largely hit the wall long ago. Nor will it come about from a finer grid as computing resources are already strained, nor from code tweaks as the latest are already in use.

The opportunities more likely lie in advanced processing of the satellite input data that resets the daily initial state. Two that come to mind are UH AMSR2 3.125 km concentration and UH SMOS-Cryosat2 thin ice. The appeal of these is that the algorithm doesn't need to change, only pointers to better input.

From our perspective, since neither makes forecasts but both are compatibly formatted as netCDFs with merger of the three datasets seamlessly supported within Panoply, we may be able to go forward on our own with hybrid products rather than wait on NOAA's timetable.

In twelve days time, we could revisit this particular ESRL prediction by comparing it to what actually transpired around the ice pack periphery according to SMOS and AMSR2. The advance with Panoply is that we can walk back the comparisons from colored map projections to the data grids themselves with no need for matlab, command line, or number viewing.

Another option is to utilize narrow but better products in reanalysis. That is, ESRL is concerned with forecasts, not hindcasts. Here we could take for example SMOS, mask out places where its signal saturates (becomes unreliable), and use the rest of it (where it is more accurate) to replace less accurate peripheral thickness in ESRL initial states. This can be done seamlessly within a shared palette in Panoply. The hybrid is then like a reanalysis product. It does not make forecasts but could be lead in to such products as the earlier frames.

Technical note: UH SMOS is seasonal, limited to ice <1.3 m thick and suffers from a larger pole hole; its posted date lags two days behind calendar and one day behind UH AMSR2. The latter is shown below with the fixed open water boundary of Oct 1st in dark gold superimposed on the other dates.
« Last Edit: October 12, 2017, 10:06:18 PM by A-Team »

Shared Humanity

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Re: 2017 sea ice area and extent data
« Reply #536 on: October 13, 2017, 05:32:17 PM »
2017 SIE trend is definitely tracking with the pack regarding rate of increase.

Feeltheburn

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Re: 2017 sea ice area and extent data
« Reply #537 on: October 13, 2017, 06:41:38 PM »
2017 SIE trend is definitely tracking with the pack regarding rate of increase.

On 12 Oct 2017 the extent according to NSIDC is 800k km2 higher than same day last year after a jump of >200k km2 in one day. I am not impressed by one day blips, because they even out, but extent has increased more than 1,000,000 km2 since 9 Sept 2017.

The ice extent increased only 328k km2 during the same time frame in 2016, but then started accelerating 14 Oct 2016. So it will be an interesting horse race.
Feel The Burn!

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Re: 2017 sea ice area and extent data
« Reply #538 on: October 18, 2017, 03:26:58 PM »
Updating NSIDC extent and area graphs.

Cato

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Re: 2017 sea ice area and extent data
« Reply #539 on: October 19, 2017, 11:31:36 AM »
+ 200 k  :o

Jim Pettit

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Re: 2017 sea ice area and extent data
« Reply #540 on: October 19, 2017, 12:56:09 PM »
+ 200 k  :o

Which metric went up 200k?

Pavel

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Re: 2017 sea ice area and extent data
« Reply #541 on: October 19, 2017, 01:30:28 PM »
Of course cold water freeze quickly since it's polar night already north of 80 latitude and days are short southward.

Cato

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Re: 2017 sea ice area and extent data
« Reply #542 on: October 19, 2017, 01:48:05 PM »
+ 200 k  :o

Which metric went up 200k?

JAXA today gives 6,776 for 18th October which makes about 187 k up from 17th? Unless I'm mistaken of course...

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Re: 2017 sea ice area and extent data
« Reply #543 on: October 19, 2017, 02:10:07 PM »
Which metric went up 200k?

JAXA today gives 6,776 for 18th October which makes about 187 k up from 17th? Unless I'm mistaken of course...
[/quote]

I gotcha. FWIW, that 187k jump is 56k above the IJIS 10-year average for the date, and comes after four consecutive days of sub-average increases that added up to 162k below that average. As has been noted before, this is peak growth week for extent, with the seven days beginning on Oct. 16 averaging about 136k of growth per day. (The largest day for growth is the 21st, which has averaged 151k over the past ten years.) After that, the trend slowly decreases up to the spring maximum.
« Last Edit: October 19, 2017, 02:49:31 PM by Jim Pettit »

Cato

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Re: 2017 sea ice area and extent data
« Reply #544 on: October 19, 2017, 04:01:20 PM »
Thanks Jim, very interesting points! Guess the inflection point where the extent increase slows down (and the envelope becomes 'thinner' as a result) more or less coincides with the freezing of ESS and Chuckchi, right?

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Re: 2017 sea ice area and extent data
« Reply #545 on: October 19, 2017, 04:03:42 PM »
Double century for NSIDC NT extent.

A one-week 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%.

aperson

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Re: 2017 sea ice area and extent data
« Reply #546 on: October 19, 2017, 10:13:39 PM »
SSTs seem slightly below average where Atlantic melt is still progressing heavily in the above 1-week differential image (although it's near an extreme temperature gradient): https://earth.nullschool.net/#2017/10/18/0000Z/ocean/surface/currents/overlay=sea_surface_temp_anomaly/orthographic=-15.20,79.95,1605/loc=6.309,77.936

Juan C. García

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Re: 2017 sea ice area and extent data
« Reply #547 on: October 20, 2017, 09:42:03 PM »
A e-mail from NSIDC:

Dear Colleague,

The Sea Ice Index has been updated to Version 3 (V3). The key update in this version is a change to the algorithm used for monthly average extent and area values. The update was driven by assessments of the averaging method by both the scientific and broader NSIDC/Sea Ice Index user community, as rapid changes in daily sea ice extent on a monthly time scale can be represented differently in a monthly average, depending on the order in which the spatial and time components are considered. The V3 monthly-average methodology is based on the simple average of daily extent values, while the V2 methodology was based on the gridded monthly-average concentration. Now, if one were to average the Sea Ice Index daily data values, the results will match the monthly average Sea Ice Index data values. Both methodologies are valid and defensible ways of assessing sea-ice extent data, but the goal of this change is to better match the understanding of the user community as the product evolves through time. The underlying daily data record remains the same as in previous versions of the dataset.

...
For the Arctic, the largest difference in monthly-average extent between V3 and V2 occurred in October 2012, where V3 is 1.2 million sq km less than V2. All other absolute differences in monthly extent are smaller than this. The average absolute difference between the two versions is 0.23 million sq km (89,000 sq miles) representing an area roughly the size of Minnesota.
...
Which is the best answer to Sep-2012 ASI lost (compared to 1979-2000)?
50% [NSIDC Extent] or
73% [PIOMAS Volume]

Volume is harder to measure than extent, but 3-dimensional space is real, 2D's hide ~50% thickness gone.
-> IPCC/NSIDC trends [based on extent] underestimate the real speed of ASI lost.

Juan C. García

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Re: 2017 sea ice area and extent data
« Reply #548 on: October 20, 2017, 10:02:07 PM »
A e-mail from NSIDC:
For the Arctic, the largest difference in monthly-average extent between V3 and V2 occurred in October 2012, where V3 is 1.2 million sq km less than V2. All other absolute differences in monthly extent are smaller than this. The average absolute difference between the two versions is 0.23 million sq km (89,000 sq miles) representing an area roughly the size of Minnesota.

Feels good to have the reason, from time to time:

In 2013 I made some analysis on the importance of this difference between the NSIDC statistical and official averages. And the difference are important in other months, specially in October.

 :)
Which is the best answer to Sep-2012 ASI lost (compared to 1979-2000)?
50% [NSIDC Extent] or
73% [PIOMAS Volume]

Volume is harder to measure than extent, but 3-dimensional space is real, 2D's hide ~50% thickness gone.
-> IPCC/NSIDC trends [based on extent] underestimate the real speed of ASI lost.

Juan C. García

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Re: 2017 sea ice area and extent data
« Reply #549 on: October 20, 2017, 10:49:14 PM »
From my point of view, the bounce that we could see on 2015-17 is just fake. We must see the weakness on the ASI and the entire year, not just September, that can be influenced by a negative feedback.

One of the most important differences between NSIDC V2.1 and 3.0, is that in V 3.0, 2016 becomes the third lowest on September, instead of the fifth lowest.

Lowest  Year     Extent
1         2012      3.57
2         2007      4.27
3         2016      4.51
4         2011      4.56
5         2015      4.62
6         2008      4.69
7         2017      4.80
8         2010      4.87
9         2013      5.21
10       2014      5.22

In a way, it upset me to see that 2016 was the fifth lowest, when I was sure that it was a terrible year.

2017 is also a terrible year (surely second worse after 2012, but taking volume into account and looking to the entire year, not just september).
« Last Edit: October 20, 2017, 11:06:25 PM by Juan C. García »
Which is the best answer to Sep-2012 ASI lost (compared to 1979-2000)?
50% [NSIDC Extent] or
73% [PIOMAS Volume]

Volume is harder to measure than extent, but 3-dimensional space is real, 2D's hide ~50% thickness gone.
-> IPCC/NSIDC trends [based on extent] underestimate the real speed of ASI lost.