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Author Topic: Sea Ice Extent around Antarctica  (Read 102966 times)

gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #650 on: July 06, 2017, 03:25:17 PM »
Antarctic Sea Ice Extent about to slip from lowest to 2nd lowest behind 1986.
(http://nsidc.org/arcticseaicenews/charctic-interactive-sea-ice-graph/).

Still an impressive reduction over the last 3 years.


Darvince

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Re: Sea Ice Extent around Antarctica
« Reply #651 on: July 09, 2017, 11:18:22 AM »
I have often wondered throughout this freezing season whether we have seen a switch back to the low ice of the 70s and 80s, but all the comments about how Antarctic sea ice is so intensely variable have kept me from stating it outright.

However, we are now in July, less than a month away from when Antarctic ice begins its wobble about the maximum, and it's still lowest on record on JAXA and seems like it's going to stay that way unless we get a 300k km² growth spurt over the next two days.

Compared to 1986 the winds seem like they've been much stronger this year, as the sea ice shape looks more like the September shape of the 80s rather than its July shape.
ftp://sidads.colorado.edu/pub/DATASETS/nsidc0051_gsfc_nasateam_seaice/final-gsfc/browse/south/daily/1986/nt_19860708_n07_v1.1_s.png
ftp://sidads.colorado.edu/pub/DATASETS/nsidc0081_nrt_nasateam_seaice/browse/south/nt_20170707_f18_nrt_s.png

gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #652 on: July 17, 2017, 03:14:01 PM »
Antarctic Sea Ice Extent once again lowest in the satellite record.

Wipneus

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Re: Sea Ice Extent around Antarctica
« Reply #653 on: July 17, 2017, 04:29:41 PM »
Also area has taken the lowest position. Looking at the graphs, extent will likely stay lowest a bit longer, area probably not.

extent SH
1985-07-16 15.775432
1995-07-16 15.732109
1980-07-16 15.615618
1989-07-16 15.592934
1990-07-16 15.502736
1986-07-16 15.480906
2002-07-16 15.480702
1983-07-16 15.480661
1991-07-16 15.451098
2017-07-16 15.024859

area SH
1982-07-16 12.455222
1995-07-16 12.433007
1986-07-16 12.352278
2001-07-16 12.349878
1987-07-16 12.341766
2011-07-16 12.240798
1990-07-16 12.224225
1991-07-16 12.200350
1980-07-16 12.178648
2017-07-16 12.141301

AbruptSLR

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Re: Sea Ice Extent around Antarctica
« Reply #654 on: July 18, 2017, 04:13:21 PM »
Modeling Antarctic sea ice is complex and modeling the implications of changes in Antarctic sea ice is even more complex (i.e. Hansen's ice-climate feedback is made more positive by the presences of this sea ice):

Roach, L. A., Dean, S. M., and Renwick, J. A.: Consistent biases in Antarctic sea ice concentration simulated by climate models, The Cryosphere Discuss., https://doi.org/10.5194/tc-2017-131, in review, 2017.

http://www.the-cryosphere-discuss.net/tc-2017-131/

Abstract. The simulation of Antarctic sea ice in global climate models often does not agree with observations. In this study, we examine the compactness of sea ice, as well as the regional distribution of sea ice concentration, in climate models from the latest Coupled Model Intercomparison Project (CMIP5) and in satellite observations. We find substantial differences in concentration values between different sets of satellite observations, requiring careful treatment when comparing to models. As a fraction of total sea ice extent, models simulate too much loose, low-concentration sea ice cover throughout the year, and too little compact, high-concentration cover in the summer. In spite of the differences in physics between models, these tendencies are broadly consistent across the population of 27 CMIP5 simulations, a result not previously highlighted. Targeted model experiments with a coupled ocean – sea ice model show that over-estimation of low-concentration cover is partially determined by choice of constant floe diameter in the lateral melt scheme. This suggests that current sea ice thermodynamics contribute to the inadequate simulation of the low-concentration regime.
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gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #655 on: Today at 02:54:47 PM »
It seems to be a rule that the more we need to know about something the less we do. The Antarctic, the Oceans, the Arctic come to mind.

Meanwhile, despite ferocious sea ice drift leading to high daily increases in extent at a time one expects a reduction, Antarctic Sea Ice is currently lowest in extent in the satellite record.