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Author Topic: Sea Ice Extent around Antarctica  (Read 282022 times)

gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #1250 on: June 19, 2019, 08:33:01 AM »
JAXA ANTARCTIC Sea Ice Extent : 12,367,006 km2(June 18, 2019)

Extent gains more below than above average in the last week.
2019 remains lowest in the satellite record for the 68th day this year, extent now 296 k below 2017.

- Extent gain on this day 125k, 18 k more than the average gain of 107 k on this day.
- Extent gain from minimum is 9.942 million km2, 1.075 million km2 (10%) less than the average of 11.018 million km2 by this day,
- 68.9% of average extent gain done, with 90 days to average date of maximum (16 Sept).

The Perils of Projections
Remaining average freeze of last 10 years gives a max of 17.36 million km2, 0.71 million km2 less than 2017 (the record low maximum year).
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gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #1251 on: June 22, 2019, 11:25:50 AM »
JAXA ANTARCTIC Sea Ice Extent :  12,763,937  km2(June 21, 2019)

Extent gains suddenly increased strongly in the last 3 days .
However, 2019 remains lowest in the satellite record (for 71 days this year), extent now just 74 k below 2017 and 675k below 2018.

- Extent gain on this day 154k, 54 k more than the average gain of 100 k on this day.
- Extent gain from minimum is 10.339 million km2, 0.950 million km2 (8.4%) less than the average of 11.289 million km2 by this day,
- 70.6% of average extent gain done, with 87 days to the average date of maximum (16 Sept).

The Perils of Projections
Remaining average freeze of the last 10 years gives a max of 17.48 million km2, 0.58 million km2 less than 2017 (the record low maximum year).
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"Para a Causa do Povo a Luta Continua!"
"And that's all I'm going to say about that". Forrest Gump
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gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #1252 on: June 22, 2019, 01:01:49 PM »
The Sea Ice Predictions Network June report https://www.arcus.org/sipn/sea-ice-outlook/2019/june has a bit about the Antarctic maximum. It looks like my "heuristic" estimate for the September maximum is closest to the UK METOFFICE prediction.

Quote
Antarctic Discussion
As was the case last year, there were several submissions for Antarctic ice extent. This year, six outlooks of September mean sea-ice extent were received (compared to 12 for last year). The six forecasts span a range of 17.0–20.9 million square kilometers (Figure 18), which largely surpasses the range in the observed satellite record. This is a remarkable range compared to the Arctic submissions.

From the (small) ensemble available, it can be surmised that the prediction systems taken together will probably not outperform a climatological or a persistence-based forecast. The next set of submissions (July and August) may be telling in this regard. Caution should be exercised in interpretation of the results as the circumpolar sea-ice extent is a diagnostic with little physical relevance.

The sister project of SIPN2, the Sea Ice Prediction Network South (SIPN South, http://acecrc.org.au/sipn-south/) aims at analyzing in more detail the (summer) Antarctic sea ice forecasts, understand the regional expressions of forecast biases, and deliver information that is more tailored to end users.
"Para a Causa do Povo a Luta Continua!"
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gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #1253 on: June 27, 2019, 09:23:49 AM »
JAXA ANTARCTIC Sea Ice Extent :  13,431,387 km2(June 26, 2019)

A big change in the last week.

Extent gains suddenly increasing strongly in the last week, has knocked extent off its perch in pole position. 2019 now 2nd lowest in the satellite record, 131 k above 2017 and 553k below 2018.

- Extent gain on this day 186k, 93 k more than the average gain of 93 k on this day.
- Extent gain from minimum is 11.007 million km2, 0.716 million km2 (6.1%) less than the average of 11.723 million km2 by this day,
- 73.4% of average extent gain done, with 82 days to the average date of maximum (16 Sept).

The Perils of Projections
Remaining average freeze of the last 10 years gives a max of 17.70 million km2, 0.36 million km2 less than 2017 (the record low maximum year).
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"Para a Causa do Povo a Luta Continua!"
"And that's all I'm going to say about that". Forrest Gump
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gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #1254 on: July 01, 2019, 11:40:12 AM »
JAXA ANTARCTIC Sea Ice Extent :  13,717,589 km2(June 30, 2019)

The last week started with very high extent gains and finished with - very low extent gains. 2019 is now 2nd lowest in the satellite record, 85 k above 2017 and 668 k below 2018.

- Extent gain on this day 40 k, 46 k less than the average gain of 86 k on this day.
- Extent gain from minimum is 11.293 million km2, 0.731 million km2 (6.1%) less than the average of 12.024 million km2 by this day,
- 75.5% of average extent gain done, with 78 days to the average date of maximum (16 Sept).

The Perils of Projections
Remaining average freeze of the last 10 years gives a max of 17.65 million km2, 0.41 million km2 less than 2017 (the record low maximum year).
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"Para a Causa do Povo a Luta Continua!"
"And that's all I'm going to say about that". Forrest Gump
"Damn, I wanted to see what happened next" (Epitaph)

Bugalugs

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Re: Sea Ice Extent around Antarctica
« Reply #1255 on: July 02, 2019, 12:57:41 AM »
Layman's view  ;D ... looks like 2017, 2018 and 2019 mark a major shift, unless strange things happen in threes at the South Pole.


gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #1256 on: July 02, 2019, 03:43:40 PM »
Layman's view  ;D ... looks like 2017, 2018 and 2019 mark a major shift, unless strange things happen in threes at the South Pole.
Reached a max in 2014, collapsed in 2016, and has stayed low. What next?
A new lower but stable state?
More loss to come?
Sea ice to recover?

Meanwhile, NASA & The US National Academy of Sciences have brought it to our attention (like we hadn't noticed?)

https://www.theguardian.com/world/2019/jul/01/precipitous-fall-in-antarctic-sea-ice-revealed
'Precipitous' fall in Antarctic sea ice since 2014 revealed
Plunge is far faster than in Arctic and may lead to more global heating, say scientists


Link to article
https://www.pnas.org/content/early/2019/06/25/1906556116
A 40-y record reveals gradual Antarctic sea ice increases followed by decreases at rates far exceeding the rates seen in the Arctic

There have been papers trying to explain this big change. This paper seems to accept that the climate system, especially connections across the globe, is not fully understood.


"Para a Causa do Povo a Luta Continua!"
"And that's all I'm going to say about that". Forrest Gump
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gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #1257 on: July 07, 2019, 09:10:27 AM »
JAXA ANTARCTIC Sea Ice Extent :  14,330,778 km2(July 6, 2019)

The last week a mixture of low and high extent gains. 2019 is now 2nd lowest in the satellite record, 42 k above 2017 and 577 k below 2018.

- Extent gain on this day 114 k, 14 k more than the average gain of 100 k on this day.
- Extent gain from minimum is 11.906 million km2, 0.605 million km2 (4.8%) less than the average of 12.511 million km2 by this day,
- 78.6% of average extent gain done, with 72 days to the average date of maximum (16 Sept).

The Perils of Projections
Remaining average freeze of the last 10 years gives a max of 17.77 million km2, 0.29 million km2 less than 2017 (the record low maximum year).
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"Para a Causa do Povo a Luta Continua!"
"And that's all I'm going to say about that". Forrest Gump
"Damn, I wanted to see what happened next" (Epitaph)

prokaryotes

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Re: Sea Ice Extent around Antarctica
« Reply #1258 on: July 09, 2019, 12:27:33 AM »


Made this video on recent Parkinson et al. PNAS paper, feedback is welcome. Though the more extended version posted here https://climatestate.uscreen.io/programs/the-mystery-of-the-antarctic-sea-ice-puzzle goes into more details with the ozone hole, and includes a brief segment from this 2018 talk https://climatestate.uscreen.io/programs/the-circulation-of-the-antarctic-margins-in-a-changing-climate by NASA's Andy Thompson, who elaborates on grounding line - slope vortexes, eddies, models, and SAM.

The main take-away from Parkinson et al, for me is, that the Amundsen current feeds into the WAIS region, while sea-ice there also most extensively in decline.
CLIMATE STATE WEBSITE | YOUTUBE | USCREEN

gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #1259 on: July 14, 2019, 09:52:31 AM »
JAXA ANTARCTIC Sea Ice Extent :  15,077,869 km2(July 13, 2019)

July so far has seen a run of high extent gains. 2019 is now 2nd lowest in the satellite record, 216 k above 2017 and 364 k below 2018.

- Extent gain on this day 79 k, 11 k more than the average gain of 68 k on this day.
- Extent gain from minimum is 12.653 million km2, 0.387 million km2 (3.0%) less than the average of 13.040 million km2 by this day,
- 82.0% of average extent gain done, with 65 days to the average date of maximum (16 Sept).

The Perils of Projections
Remaining average freeze of the last 10 years gives a max of 17.97 million km2, 0.09 million km2 less than 2017 (the record low maximum year).

This is a significant upwards change in extent from the end of June.
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"Para a Causa do Povo a Luta Continua!"
"And that's all I'm going to say about that". Forrest Gump
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gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #1260 on: July 16, 2019, 06:03:49 AM »
JAXA ANTARCTIC Sea Ice Extent :  15,408,430 km2(July 15, 2019)

July so far has seen a run of high to extreme extent gains. 2019 is now 2nd lowest in the satellite record, 435 k above 2017 and 113 k below 2018.

- Extent gain on this day 188 k, 149 k more than the average gain of 39 k on this day.
- Extent gain from minimum is 12.984 million km2, 0.147 million km2 (1.1%) less than the average of 13.130 million km2 by this day,
- 82.4% of average extent gain done, with 63 days to the average date of maximum (16 Sept).

The Perils of Projections
Remaining average freeze of the last 10 years gives a max of 18.23 million km2, 3rd lowest in the satellie record, and 0.17 million km2 greater than 2017 (the record low maximum year).

This is a significant upwards change in extent from the end of June.
______________________________________________________________________
"Para a Causa do Povo a Luta Continua!"
"And that's all I'm going to say about that". Forrest Gump
"Damn, I wanted to see what happened next" (Epitaph)

Darvince

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Re: Sea Ice Extent around Antarctica
« Reply #1261 on: July 16, 2019, 03:25:03 PM »
It's 3rd now, additionally above 2002. If there is a gain of at least ~180,000 km2 for the 16th, it could become 7th.

Stephan

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Re: Sea Ice Extent around Antarctica
« Reply #1262 on: July 16, 2019, 07:19:06 PM »
If you look at Climate Reanalyzer, for weeks now the SST anomaly around the sea ice edge is below zero almost around the globe. This should help ice to grow a little faster than usual (→ higher gains than average) IMO.