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Tigertown

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Re: Sea Ice Extent around Antarctica
« Reply #450 on: February 12, 2017, 05:30:25 AM »
For Feb. 11th JAXA has posted 2,236,777 km2 for SIE around Antarctica.

Paddy

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Re: Sea Ice Extent around Antarctica
« Reply #451 on: February 12, 2017, 08:31:07 AM »
Down another bin in the poll... Will this be the final bin, or will it go one lower?

Lord M Vader

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Re: Sea Ice Extent around Antarctica
« Reply #452 on: February 12, 2017, 10:49:34 AM »
Paddy: It depends on what's going to happen with the loosy ice in Amundsen Sea. From University of Bremens page you can see how fragmentated that ice is.

From CCI_Reanalyzer, cool weather is forecasted for the "northern half" of Antarctica while warmer anomalies will hover in the "southern half" of the continent.

I'm fairly sure we'll see a very early minimum but an overall rather slow freeze up.

Bill Fothergill

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Re: Sea Ice Extent around Antarctica
« Reply #453 on: February 12, 2017, 12:51:42 PM »
For Feb. 11th JAXA has posted 2,236,777 km2 for SIE around Antarctica.

Here's what that looks like on an extent chart. I've zoomed to the relevant period of ~ 7 weeks, and filtered it to just include the decadal averages, 2016, 2017 and the 3 lowest minima...

NB Remember that the period 2013 - 2015 saw record high extent levels in the Antarctic. We need to wait and see if this is yet another wild fluctuation, or whether the Antarctic is finally settling in to a long-term decline in the same fashion as its boreal cousin.

Pavel

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Re: Sea Ice Extent around Antarctica
« Reply #454 on: February 12, 2017, 01:09:39 PM »
The ice in polynya in the south of Weddel sea seems have started to refreeze since it's begining ice-covered without any ice advection, it's really cold there. But everywhere except Weddel sea is really warm and melting momentum continues. The ice pack in the East is weak but extent is higher than usual. Many depends on the wind patterns whether it will spread or compact the ice pack. But anyway it's a record warm warm warm year

Lord M Vader

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Re: Sea Ice Extent around Antarctica
« Reply #455 on: February 12, 2017, 01:36:32 PM »
Another drop today, down 21K to 2,288 Mn km2 but still third lowest on record.

1997-02-27: 2,264 Mn km2
1993-02-19: 2,281 Mn km2
2017-02-11: 2,288 Mn km2

Tomorrow is another day... Then we'll know if we have surpassed the 1993 minimum or if we have reached the bottom...

Bill Fothergill

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Re: Sea Ice Extent around Antarctica
« Reply #456 on: February 12, 2017, 02:10:29 PM »
Another drop today, down 21K to 2,288 Mn km2 but still third lowest on record.

1997-02-27: 2,264 Mn km2
1993-02-19: 2,281 Mn km2
2017-02-11: 2,288 Mn km2

Tomorrow is another day... Then we'll know if we have surpassed the 1993 minimum or if we have reached the bottom...

Here is the Charctic rolling 5-day average. As with the ADS/IJIS chart posted earlier, I've zoomed and filtered so that it just shows 1993, 1997, 2011, 2016 & 2017

The local minima on this chart appear at...

Feb 27 1997;   2.290 million sq kms
Feb 19 1993:   2.312 million sq kms
Feb 25 2011;   2.339 million sq kms

Feb 19 2016;   2.603 million sq kms

The latest single-day NSIDC figure is fractionally lower than the absolute lowest 5-day Charctic value, and the five most recent single-day figures drop monotonically.

It is left to the reader to work out what that may foretell.

Wipneus

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Re: Sea Ice Extent around Antarctica
« Reply #457 on: February 12, 2017, 04:08:11 PM »
SH "NSIDC extent": -20.9k
SH "NSIDC area": +35.6k

No change in the minimum rankings, daily or annually.

Tigertown

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Re: Sea Ice Extent around Antarctica
« Reply #458 on: February 13, 2017, 04:33:22 AM »
For Feb. 12th JAXA has posted 2,226,844 km2 for SIE around Antarctica.

Lord M Vader

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Re: Sea Ice Extent around Antarctica
« Reply #459 on: February 13, 2017, 08:28:03 AM »
If the forecast from CCI_Reanalyzer is correct, there might be room for some additional melting up to February 18. By that time, it looks like Weddell Sea will sea a 960 hpa low make its entrance there and bring in some warm air and water. So let's see if might go below the 1997 record! It's time for the final battle! :)

Wipneus & Co: do you have any idea about the "big block" that's is floating freely in the Ross Sea (Univ. of Bremens map) and has done so for more than a month now.

Tealight

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Re: Sea Ice Extent around Antarctica
« Reply #460 on: February 13, 2017, 12:02:17 PM »
Wipneus & Co: do you have any idea about the "big block" that's is floating freely in the Ross Sea (Univ. of Bremens map) and has done so for more than a month now.


That is a huge Iceberg. Iceberg B30 to be exact.

On Polarview you can check radar images and track all big icebergs:
http://www.polarview.aq/antarctic

DavidR

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Re: Sea Ice Extent around Antarctica
« Reply #461 on: February 13, 2017, 01:48:34 PM »
It's GONE! Today's data from NSIDC shows that 2017 has passed the record low extent  in the Antarctic record. Down to  2.246 M km^2 with  1 -> 3 weeks of melt season still left.

Wipneus

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Re: Sea Ice Extent around Antarctica
« Reply #462 on: February 13, 2017, 03:26:09 PM »
SH "NSIDC extent": -42.2k
SH "NSIDC area": -33.5k

And indeed an all time (satellite era) low for Antarctic sea ice extent. Here is the top 5:
1 2017-02-12 2.245761
2 1997-02-27 2.264152
3 1993-02-19 2.280783
4 2011-02-22 2.318847
5 1984-02-27 2.381731


It would not be the earliest day on record if the extent happens not to go any lower: that is shared with 1994 that also minimized on 12 Feb.

Area still has some way to go, and particularly 1993 will be hard to beat:

Area
1 1993-02-26 1.248163
2 1984-02-27 1.509585
3 1996-02-25 1.535481
4 2000-02-18 1.561033
5 2006-03-04 1.565059
6 1999-02-26 1.577058
7 1981-03-03 1.588790
8 1997-02-19 1.589288
9 2017-02-10 1.606338


See also attached extent and area graphs.

DrTskoul

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Re: Sea Ice Extent around Antarctica
« Reply #463 on: February 13, 2017, 03:30:01 PM »
Particularly hard to almost impossible given the difference and the average rate of decrease..
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Red

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Re: Sea Ice Extent around Antarctica
« Reply #464 on: February 13, 2017, 06:38:45 PM »
Not sure if this is the right spot to post this but if it moves right it will have an effect on extent. Todays Worldview shot in front of the Shrase shows a new lead going from the toe to open ocean creating a lose piece of ice approx. 30 miles by 200 miles.
https://worldview.earthdata.nasa.gov/?p=antarctic&l=MODIS_Aqua_CorrectedReflectance_TrueColor,MODIS_Terra_CorrectedReflectance_TrueColor,Coastlines&t=2017-02-13&z=3&v=1298624.539286568,1699629.222484847,1564608.539286568,1871149.222484847

Lord M Vader

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Re: Sea Ice Extent around Antarctica
« Reply #465 on: February 13, 2017, 07:08:44 PM »
While the DAILY minimum got record low today according to NSIDC numbers, the 5-day average is still above the 1997 record and the next two days will be crucial to determine if we are going to have a "real" record low.

Sea ice in Amundsen Sea has taken the biggest hit the last couple of days.

Pavel

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Re: Sea Ice Extent around Antarctica
« Reply #466 on: February 13, 2017, 08:02:59 PM »
SSTs are 3-4 degrees (!) higher than in the same day of 2016 both in Antlantic and Pacific sides. It will struggle to freeze up this year.

RoxTheGeologist

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Re: Sea Ice Extent around Antarctica
« Reply #467 on: February 13, 2017, 08:14:23 PM »
Not sure if this is the right spot to post this but if it moves right it will have an effect on extent. Todays Worldview shot in front of the Shrase shows a new lead going from the toe to open ocean creating a lose piece of ice approx. 30 miles by 200 miles.
https://worldview.earthdata.nasa.gov/?p=antarctic&l=MODIS_Aqua_CorrectedReflectance_TrueColor,MODIS_Terra_CorrectedReflectance_TrueColor,Coastlines&t=2017-02-13&z=3&v=1298624.539286568,1699629.222484847,1564608.539286568,1871149.222484847

That lead is pretty wide too. I'm guessing that runs through fast ice. It shows the lead going through an ice shelf, but I think the boundary of the shelf might be incorrect. 

Bill Fothergill

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Re: Sea Ice Extent around Antarctica
« Reply #468 on: February 13, 2017, 08:15:23 PM »
While the DAILY minimum got record low today according to NSIDC numbers, the 5-day average is still above the 1997 record and the next two days will be crucial ...
If the NSIDC extent value for Jan 13th exactly equals that for the 12th (2.246 million sq kms) then the 5-day average will drop to 2.290 million sq kms - exactly equalling the record low from 1997.

Should that unlikely event occur, as long as the extent value on the 14th is lower than that recorded for the 9th Feb (2.362 million sq kms) then the 5-day record low moves into uncharted (or un-Charctic-ed) waters.

As mentioned up-thread, the 2-day smoothed ADS/IJIS/JAXA numbers for extent hit record low levels on the 11th Feb.

DavidR

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Re: Sea Ice Extent around Antarctica
« Reply #469 on: February 14, 2017, 01:52:44 PM »
If the NSIDC extent value for Jan 13th exactly equals that for the 12th (2.246 million sq kms) then the 5-day average will drop to 2.290 million sq kms - exactly equalling the record low from 1997.
Jan 13th came in at  2.230 taking the 5 day average to 2.287, breaking the record 5 day  low.

Wipneus

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Re: Sea Ice Extent around Antarctica
« Reply #470 on: February 14, 2017, 02:44:21 PM »
SH "NSIDC extent": -15.9k
SH "NSIDC area": -21.6k

This causes 2017 to move to 7th place in annual minimum SH area, skipping two places:

Area
1 1993-02-26 1.248163
2 1984-02-27 1.509585
3 1996-02-25 1.535481
4 2000-02-18 1.561033
5 2006-03-04 1.565059
6 1999-02-26 1.577058
7 2017-02-13 1.586773
8 1981-03-03 1.588790
9 1997-02-19 1.589288


Lord M Vader

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Re: Sea Ice Extent around Antarctica
« Reply #471 on: February 14, 2017, 04:46:27 PM »
FWIW, I provide some regional sea ice extent pics showing the basins where we might see some additional "melting" until refreezing starts. Will be interesting to see tomorrows number from NSIDC. The 5-day average should drop more given that the first of the past 5 days were higher than the others.

And, given the SSTA from Tropical Tidbits it will be interesting to see if we'll get some real polar amplification by March-April given the warm waters around Antarctica.

Courtesy: University of Bremen (first 2 pics) and Tropical Tidbits/Lewi cowan (third pic)


Bill Fothergill

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Re: Sea Ice Extent around Antarctica
« Reply #472 on: February 14, 2017, 05:01:26 PM »
Today's depressing Charctic image. As before, zoomed and filtered to just show 2017, 2016, 2011, 1997 & 1993.

Lord M Vader

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Re: Sea Ice Extent around Antarctica
« Reply #473 on: February 15, 2017, 01:42:55 PM »
Down to 2,224 Mn km2 and with a 5-day average down to 2,259 Mn km2. The 5-day average will likely go down somewhat the next 1-2 days as I don't see a 75K uptick likely.

Wipneus

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Re: Sea Ice Extent around Antarctica
« Reply #474 on: February 15, 2017, 02:59:20 PM »
SH "NSIDC extent": -5.6k
SH "NSIDC area": +16.4k

Daily area now third lowest:

area SH
1984-02-14 1.731623
1980-02-14 1.727033
2002-02-14 1.720928
2006-02-14 1.717069
1999-02-14 1.687074
1981-02-14 1.681987
1997-02-14 1.676127
2017-02-14 1.603165
2000-02-14 1.585860
1993-02-14 1.303875

DrTskoul

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Re: Sea Ice Extent around Antarctica
« Reply #475 on: February 15, 2017, 03:20:25 PM »
May end up second lowest.
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dingojoe

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Re: Sea Ice Extent around Antarctica
« Reply #476 on: February 15, 2017, 06:44:36 PM »
Still quite a bit of fast ice continuing to break down along the NE and SE quadrants.  Those coastlines are at lower latitudes so melt could continue along these areas into March.

be cause

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Re: Sea Ice Extent around Antarctica
« Reply #477 on: February 15, 2017, 07:02:41 PM »
Hi Bill .. any chance of moving the 'details box' so that it doesn't hide the detail ? Thanks for all the details you post :)
                         bc
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Bill Fothergill

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Re: Sea Ice Extent around Antarctica
« Reply #478 on: February 15, 2017, 08:35:00 PM »
Hi Bill .. any chance of moving the 'details box' so that it doesn't hide the detail ? Thanks for all the details you post :)
                         bc
Hi BC,

Assuming I'm the "bill" in question, the slider underneath any chart can be used to slide it to the left in order to see any temporarily hidden text. As regards the ADS/JAXA/IJIS chart and the NSIDC Charctic equivalent, I have deliberately left them undoctored (apart from the zooming/filtering) such that anyone could create an identical image for themselves.

Does that help, or did I misinterpret your meaning?

Bill Fothergill

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Re: Sea Ice Extent around Antarctica
« Reply #479 on: February 15, 2017, 08:46:49 PM »
Being a fan of rolling 12-month averages, I thought I'd do a quick analysis on the NSIDC monthly EXTENT numbers for the Antarctic. In order to keep it simple to start with, I applied equal weighting to each month. Obviously that gives slightly more weight to the month of February, but it's only a second order effect.

I then used the RANK feature in Excel, and displayed this as a "Heat Chart", as shown below. So far, there have been 448 of these rolling 12-month periods.

FEATURES TO NOTE:

1) As anyone would expect, the overall trend is one of ice growth.

2) There are repeated horizontal "stripes", indicating that this growth is anything but monotonic.

3) From the 12-month period ending April 2012 until the equivalent period ending April 2016, every data point was in the highest quartile.

4) From every such period from May 2013 until February 2016, every data point was in the highest 10-percentile.

5) During 2016 & 2017, the average has dropped precipitously at an unmatched rate, such that the two most recent data points are in the lowest 5-percentile.

6) Looking at the "December" column, it can be seen that 2016 had the second lowest end-of-year average in the entire dataset.


Using this "rough" assessment as a guide, a rolling 365-day average can be carried out on the areas of interest. (NB There are some problems with doing a blanket 365-average. In addition to some significant data drops, the sampling rate alters part way through the dataset . This is hardly insurmountable, but I'm just lazy!)

The current 365-day average extent (data as at Feb 14th 2017) is 11.056 million sq kms.

Every 365-day average ending during the entire period from early January 1987 to mid-March 1987 was lower than this, with a local minimum of ~ 11.038 million sq kms. At the present rate of decline in the 365-day average - slightly in excess of 12,000 sq kms over the last 10 days - this figure could possibly be surpassed by the end of February.

Similarly, every 365-day average ending during the period end-June 1980 until mid-October 1980 was lower than the current value of 11.056 million sq kms. The local minimum during that period dropped to 10.969 millions sq kms, and there were about ~ 62 days on which the average was below 11 million sq kms. At the present rate of decline, the 365-day rolling average might drop below 11 by early April, but would take till near the end of that month to reach record-low territory.

Wipneus

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Re: Sea Ice Extent around Antarctica
« Reply #480 on: February 16, 2017, 09:24:15 AM »
Even lower extent and area numbers are unlikely today. Calculating from Uni Hamburg ASI AMSR2 sea ice concentration data:

Date: 2017-02-15 12:00  Values in 1000 km^2

Extent (value, one day change):
Bellingshausen&Amundsen Seas                   Weddel Sea
                327.0  +33.2                1091.2   +0.4
                Indian Ocean           West Pacific Ocean
                177.8   -1.7                 496.6  +15.8
                    Ross Sea                        Total
                 76.7   -6.8                2169.4  +40.9

Area (value, one day change):
Bellingshausen&Amundsen Seas                   Weddel Sea
                260.1  +38.6                 979.6   -7.9
                Indian Ocean           West Pacific Ocean
                152.7   -1.0                 414.5   +4.8
                    Ross Sea                        Total
                 64.3   -3.9                1871.2  +30.6

Wipneus

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Re: Sea Ice Extent around Antarctica
« Reply #481 on: February 16, 2017, 02:35:22 PM »
SH "NSIDC extent": +29.5k
SH "NSIDC area": +24.5k

Area is now the 4th lowest:

area SH
1980-02-15 1.706625
2006-02-15 1.701121
2002-02-15 1.698856
1996-02-15 1.686381
1999-02-15 1.684981
1997-02-15 1.643263
2017-02-15 1.627697
1981-02-15 1.622265
2000-02-15 1.590006
1993-02-15 1.292263

Lord M Vader

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Re: Sea Ice Extent around Antarctica
« Reply #482 on: February 16, 2017, 08:27:30 PM »
Looking at CCI_Reanalyzers forecast for the next 7 days reveals the possibility of a few more days with warmer than average temps in the areas with the best chance to see some additional compaction or bottom melting before refreezing takes place.

Tigertown

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Re: Sea Ice Extent around Antarctica
« Reply #483 on: February 17, 2017, 12:18:27 AM »
Seconds ago I was watching CNN, and across the bottom of the screen it read, " Antarctic Sea Ice shrinks to a new low."

P.S. Checked online and voila.

www.cnn.com/2017/02/16/world/antarctica-sea-ice-record-low/index.html

DavidR

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Re: Sea Ice Extent around Antarctica
« Reply #484 on: February 17, 2017, 11:00:25 AM »
Not sure if this is the right spot to post this but if it moves right it will have an effect on extent. Todays Worldview shot in front of the Shrase shows a new lead going from the toe to open ocean creating a lose piece of ice approx. 30 miles by 200 miles.
https://worldview.earthdata.nasa.gov/?p=antarctic&l=MODIS_Aqua_CorrectedReflectance_TrueColor,MODIS_Terra_CorrectedReflectance_TrueColor,Coastlines&t=2017-02-13&z=3&v=1298624.539286568,1699629.222484847,1564608.539286568,1871149.222484847

That lead is pretty wide too. I'm guessing that runs through fast ice. It shows the lead going through an ice shelf, but I think the boundary of the shelf might be incorrect.
Mmm that  section of Ice has really broken up in the past few days.

charles_oil

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Re: Sea Ice Extent around Antarctica
« Reply #485 on: February 17, 2017, 08:48:16 PM »
After the CNN one there was an article on Antarctica on Al Jazeera too today

http://www.aljazeera.com/blogs/editors-blog/2017/01/wild-antarctica-scientists-robots-pancake-ice-170131140037171.html

Though I think this may be the earlier report at end of Jan.

In todays film are taking cores etc on the Mertz Glacier

Tigertown

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Re: Sea Ice Extent around Antarctica
« Reply #486 on: February 18, 2017, 05:39:02 AM »
 This probably signals the end of melt season, short of a drastic event.
 From the 14th of Feb. to the 15th.
CLICK IMAGE PLEASE
 

crandles

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Re: Sea Ice Extent around Antarctica
« Reply #487 on: February 18, 2017, 12:53:12 PM »
12215,2017,02,11,1208044800,2236777
12216,2017,02,12,1208131200,2226844
12217,2017,02,13,1208217600,2222327 lowest so far
12218,2017,02,14,1208304000,2226896
12219,2017,02,15,1208390400,2230736
12220,2017,02,16,1208476800,2232124
12221,2017,02,17,1208563200,2224767 2.4k above lowest

Too close to lowest to call it yet.

But I think we can call global extent and area minimums past per Wipneus' charts in Daily graphs.

Tigertown

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Re: Sea Ice Extent around Antarctica
« Reply #488 on: February 19, 2017, 05:30:39 AM »
For Feb. 18th JAXA has reported 2,199,214 km2 for SIE around Antarctica.

Tealight

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Re: Sea Ice Extent around Antarctica
« Reply #489 on: February 19, 2017, 09:21:09 PM »
Wipneus replacement post.

SH "NSIDC extent": -49.6k
SH "NSIDC area": -35.04k

This causes 2017 to move to 6th place in annual minimum SH area, skipping one place:

Extent
1 2017-02-18 2.220714
2 1997-02-27 2.264152
3 1993-02-19 2.280783
4 2011-02-22 2.318847

Area
1 1993-02-26 1.248163
2 1984-02-27 1.509585
3 1996-02-25 1.535481
4 2000-02-18 1.561033
5 2006-03-04 1.565059
6 2017-02-18 1.565366
7 1999-02-26 1.577058
« Last Edit: February 19, 2017, 09:45:20 PM by Tealight »

crandles

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Re: Sea Ice Extent around Antarctica
« Reply #490 on: February 19, 2017, 09:33:36 PM »

Extent
1 2017-02-02 2.220714

18 Feb 2017 I assume.

Tealight

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Re: Sea Ice Extent around Antarctica
« Reply #491 on: February 19, 2017, 09:48:18 PM »

Extent
1 2017-02-02 2.220714

18 Feb 2017 I assume.

Yes 18th Feb, thanks for spotting.

Tigertown

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Re: Sea Ice Extent around Antarctica
« Reply #492 on: February 20, 2017, 05:33:25 AM »
For Feb. 19th JAXA has posted 2,192,847 km2 for SIE around Antarctica.

Lord M Vader

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Re: Sea Ice Extent around Antarctica
« Reply #493 on: February 20, 2017, 06:37:58 PM »
For Feb 19, NSIDC reports a new record low value at 2,201 Mn km2 and a new record 5-day average at 2,242 Mn km2.

Blizzard92

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Re: Sea Ice Extent around Antarctica
« Reply #494 on: February 20, 2017, 08:27:11 PM »
A bit hard to see, but here's the latest NSIDC daily extent with added quartile ranges... http://sites.uci.edu/zlabe/antarctic-sea-ice-extentconcentration/
UC Irvine - Earth System Science Ph.D. Student
Cornell University - Atmospheric Sciences B.Sc.

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Lord M Vader

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Re: Sea Ice Extent around Antarctica
« Reply #495 on: February 21, 2017, 02:17:38 PM »
A new record low for Feb. 20. Down to 2,191 Mn km2 and a 5-day average down to 2,229 Mn km2, also a new record low value. If no refreezing occurrs for today and tomorrow, we might go down as low as 2,20 Mn km2.

georged

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Re: Sea Ice Extent around Antarctica
« Reply #496 on: February 21, 2017, 10:10:39 PM »
A new record low for Feb. 20. Down to 2,191 Mn km2 and a 5-day average down to 2,229 Mn km2, also a new record low value. If no refreezing occurrs for today and tomorrow, we might go down as low as 2,20 Mn km2.

What are we looking at for area?

Pavel

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Re: Sea Ice Extent around Antarctica
« Reply #497 on: February 21, 2017, 11:23:11 PM »
It seems the extent have reached the annual minimun since the ice pack drift outward the coast in the Weddel sea and opened polynyas freeze up rapidly. Animation 18-21Feb

Lord M Vader

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Re: Sea Ice Extent around Antarctica
« Reply #498 on: February 22, 2017, 06:58:05 AM »
Pavel: could be, but the freezing in Weddell seems to be counteracted by melting/compacting in other areas so it's possible that we could go another small bin down before the real growth starts. But yes, I woldn't be surprised if we will see upticks from now and onward. Weddell sea is cold right now.

Lord M Vader

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Re: Sea Ice Extent around Antarctica
« Reply #499 on: February 22, 2017, 06:18:41 PM »
An uptick in the daily value to 2,215 Mn km2 but a dip downward in the 5-day average to 2,220 Mn km2. If no significant uptick is reported tomorrow we should dip another bin down in the 5-day average. But, given the uptick, the forecast and the state of the Weddell Sea iit's possible that we have 1-2 more days until more sigificant refreezing starts, particularly from Friday and beyond.