Please support this Forum and Neven's Blog

Author Topic: Sea Ice Extent around Antarctica  (Read 122508 times)

Tigertown

  • ASIF Upper Class
  • Posts: 1591
    • View Profile
Re: Sea Ice Extent around Antarctica
« Reply #700 on: September 02, 2017, 10:40:06 AM »
Antarctica SIE right now reminds me of a staggering ole' drunk trying to stay on his feet.

gerontocrat

  • ASIF Middle Class
  • Posts: 606
    • View Profile
Re: Sea Ice Extent around Antarctica
« Reply #701 on: September 02, 2017, 02:11:42 PM »
Antarctic sea ice extent (JAXA data) reached a maximum of 17.640 million km2 on 25th August. 7 days later it is 125,000 km2 less at 17.515 million km2. In this period the average gain is 250,000 km2.
However, there are often big ups and downs in September, so a surprise may be in store either way, especially given average date of maximum is more like around the 20th September. If 25th August ends up as the date of maximum (2016 was on 29th August) - good heavens.

So, like a fool I will prognosticate a maximum extent of less than 18 million km2.

« Last Edit: September 02, 2017, 02:21:56 PM by gerontocrat »
"Para a Causa do Povo a Luta Continua!"

Tigertown

  • ASIF Upper Class
  • Posts: 1591
    • View Profile
Re: Sea Ice Extent around Antarctica
« Reply #702 on: September 03, 2017, 04:02:06 PM »
NSIDC SIE for Antarctica has really leveled off or stalled. JAXA is similar, but they have not updated for 9-2-2017 yet.

steve s

  • ASIF Lurker
  • Posts: 40
    • View Profile
Re: Sea Ice Extent around Antarctica
« Reply #703 on: September 03, 2017, 06:35:20 PM »
Looks to me like the sea ice extent took a step downward in August 2016, and stayed down thereafter. An energy distribution change of some kind. What other event or events may be time correlated?

I wrote 'may' because the other events may be earlier or later due to transmission effects and the cause may be a separate matter, but the step nature of the shift is clear. The shift is as interesting a phenomenon as it is frightening.   

Tigertown

  • ASIF Upper Class
  • Posts: 1591
    • View Profile
Re: Sea Ice Extent around Antarctica
« Reply #704 on: September 03, 2017, 07:08:49 PM »
Looks to me like the sea ice extent took a step downward in August 2016, and stayed down thereafter. An energy distribution change of some kind. What other event or events may be time correlated?

I wrote 'may' because the other events may be earlier or later due to transmission effects and the cause may be a separate matter, but the step nature of the shift is clear. The shift is as interesting a phenomenon as it is frightening.
Do you mean to say September 2016?

steve s

  • ASIF Lurker
  • Posts: 40
    • View Profile
Re: Sea Ice Extent around Antarctica
« Reply #705 on: September 03, 2017, 07:43:04 PM »
Oops I was misreading where months begin in your graph. The change began around or just after the beginning of September 2016 and took 10 days to 2 weeks to complete, as I now read the graph.

gerontocrat

  • ASIF Middle Class
  • Posts: 606
    • View Profile
Re: Sea Ice Extent around Antarctica
« Reply #706 on: September 04, 2017, 11:12:23 AM »
JAXA DATA

What an end of season at both ends of the earth.
Table 1 shows some possible outcomes, including August 25th as the maximum
On 5th Nov 2016 sea ice extent became the lowest in the satellite record, and stayed that way for over 150 days. Since then, apart from a few days at 4th lowest, extent has been 3rd, 2nd or 1st lowest. We are in the third year of significant decline. (see Table 2)

In 2016 extent dropped suddenly after 29th August - (see graph). Will 2017 follow this pattern?
"Para a Causa do Povo a Luta Continua!"

gerontocrat

  • ASIF Middle Class
  • Posts: 606
    • View Profile
Re: Sea Ice Extent around Antarctica
« Reply #707 on: September 06, 2017, 11:12:11 AM »
With 3 days increase in extent, 5th September a wopping 189,000 km2, The maximum extent to date is now 17.72 km2, i.e. 25th August is NOT the date of maximum.
"Para a Causa do Povo a Luta Continua!"

AbruptSLR

  • ASIF Emperor
  • Posts: 12736
    • View Profile
Re: Sea Ice Extent around Antarctica
« Reply #708 on: September 07, 2017, 05:39:40 PM »
I have the feeling that with continued climate change we had better get used to 'perfect storm' occurrences, as they will soon be common place events:

Title: "Record-low 2016 Antarctic sea ice due to 'perfect storm' of tropical, polar conditions"

http://www.spacedaily.com/reports/Record_low_2016_Antarctic_sea_ice_due_to_perfect_storm_of_tropical_polar_conditions_999.html
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

steve s

  • ASIF Lurker
  • Posts: 40
    • View Profile
Re: Sea Ice Extent around Antarctica
« Reply #709 on: September 07, 2017, 07:23:30 PM »
Last year's sea ice extent a perfect storm of coincidences? Then why does this year seem so similar? I find it much easier to imagine a single driver than the squared product of low probabilities.

Buddy

  • ASIF Upper Class
  • Posts: 1981
  • Go DUCKS!!
    • View Profile
Re: Sea Ice Extent around Antarctica
« Reply #710 on: September 07, 2017, 09:53:20 PM »
Steve S.....absolutely right.  This is just the continuation of the basic physics in play.  And as temperatures continue to rise....along with sea levels....the science deniers will continue to mislead and lie.

FOX News has been lying about global warming for over 20 years.....and they were the biggest supporter of SCROTUS.

Donnie Trump, FOX, Bastardi, Hannity, Rick Scott, Mike Pence, Mitch McConell, Paul Ryan, Marco Rubio, etc.....

But to get back to your point.....I look for a continuation of the drop in global ice, and an acceleration of it...
FOX (TASS) News....."The Trump Channel.....where truth and journalism are dead."

AbruptSLR

  • ASIF Emperor
  • Posts: 12736
    • View Profile
Re: Sea Ice Extent around Antarctica
« Reply #711 on: September 08, 2017, 05:18:32 PM »
Obviously, the data presented in the linked article was taken before the Antarctic sea ice extent began to retreat last year:

Katlein, C., Hendricks, S., and Key, J.: Brief communication: Increasing shortwave absorption over the Arctic Ocean is not balanced by trends in the Antarctic, The Cryosphere, 11, 2111-2116, https://doi.org/10.5194/tc-11-2111-2017, 2017.

https://www.the-cryosphere.net/11/2111/2017/?utm_content=bufferf747e&utm_medium=social&utm_source=twitter.com&utm_campaign=buffer

Abstract. On the basis of a new, consistent, long-term observational satellite dataset we show that, despite the observed increase of sea ice extent in the Antarctic, absorption of solar shortwave radiation in the Southern Ocean poleward of 60° latitude is not decreasing. The observations hence show that the small increase in Antarctic sea ice extent does not compensate for the combined effect of retreating Arctic sea ice and changes in cloud cover, which both result in a total increase in solar shortwave energy deposited into the polar oceans.
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

steve s

  • ASIF Lurker
  • Posts: 40
    • View Profile
Re: Sea Ice Extent around Antarctica
« Reply #712 on: September 08, 2017, 07:37:23 PM »
Not a surprising finding, ASLR; but there seems to have been a stair-step shift in sea ice extent, not the gradual change that article suggests. The cause of that step-wise shift begs explanation. We do not know whether the shift might repeat or the reason for its scale. Without gradualism, we are blinder than we knew.
« Last Edit: September 09, 2017, 06:12:20 PM by steve s »

gerontocrat

  • ASIF Middle Class
  • Posts: 606
    • View Profile
Re: Sea Ice Extent around Antarctica
« Reply #713 on: September 09, 2017, 01:06:34 PM »
JAXA extent is now 17.85 million km2, i.e. increasing. Will the max be below 2016? If yes, then it will be three consecutive lower maxima from 2014.

I also attach an image from cci-reanalyzer of the 5 day max temp forecast, as it shows very well how those beautiful near perfect circles of temperature gradients are being disrupted as warmth returns.
"Para a Causa do Povo a Luta Continua!"

Wipneus

  • ASIF Governor
  • Posts: 3556
    • View Profile
    • Arctische Pinguin
Re: Sea Ice Extent around Antarctica
« Reply #714 on: September 12, 2017, 07:11:57 PM »
It is still possible that 2017 will record lowest maximum extent and/or lowest maximum area.
But it is getting close, and the latest maximums were reached 3rd of October 1988.

Here are the year with lowest maximums:

SH Extent

35 2008-09-03 18.297985
36 1989-09-23 18.274455
37 2002-09-09 18.116289
38 1986-09-18 18.026832
39 2017-09-11 17.969850

SH Area

35 1979-09-05 14.515589
36 2016-08-28 14.493985
37 1984-09-04 14.493378
38 1986-09-18 14.177269
39 2017-09-08 14.104656

gerontocrat

  • ASIF Middle Class
  • Posts: 606
    • View Profile
Re: Sea Ice Extent around Antarctica
« Reply #715 on: September 14, 2017, 12:47:42 PM »
JAXA Data
Extent on 13th Sept is 18.03 million km2.

On 12th September extent exceeded 2016 extent for the first time. Extent on 13th September  is now 0.2 million km2 greater than 2016 on that date.
On the other hand it still looks more likely that the 2017 maximum will be less than the 2016  maximum of 18.5 million on 29th August (see table).

For me the next two key events are
 - the maximum extent c.f. 2016,
- November 5th - on that date 2016 extent became the lowest in the satellite record. Will 2017 be the same?
"Para a Causa do Povo a Luta Continua!"

Adam Ash

  • ASIF Citizen
  • Posts: 243
    • View Profile
    • The 100 metre line
Re: Sea Ice Extent around Antarctica
« Reply #716 on: September 14, 2017, 01:28:20 PM »
I have just re-read Hansen et al Ice melt, sea level rise and superstorms (2015).  Expansion of sea ice around Antartica is entirely in line with impacts of increased forcing due to CO2 et al.  The resulting increase in ice melt at both ends of the planet will lower sea surface temperatures there for a while, as well as reducing or stopping the major Meridional Overturning Circulations which screws heat distribution.  Then the increased atmospheric energy gradients (especially the much warmer equatorial regions) create storms of increasingly-unimaginable intensity. 
If we get a 'minimum maximum' around Antarctic this year I think it will be a blessing, but that's not what the forecast for the next few decades/centuries looks like, until ice melt slows again.

gerontocrat

  • ASIF Middle Class
  • Posts: 606
    • View Profile
Re: Sea Ice Extent around Antarctica
« Reply #717 on: September 15, 2017, 03:06:43 PM »
The question for me is more immediate. Will 2017 continue the decline in extent started in 2014 or will it (as often happens) just merge into the pack?
"Para a Causa do Povo a Luta Continua!"

Tigertown

  • ASIF Upper Class
  • Posts: 1591
    • View Profile
Re: Sea Ice Extent around Antarctica
« Reply #718 on: September 15, 2017, 05:59:05 PM »
The question for me is more immediate. Will 2017 continue the decline in extent started in 2014 or will it (as often happens) just merge into the pack?
I think we will find out over the next two weeks where this season is going.

Wipneus

  • ASIF Governor
  • Posts: 3556
    • View Profile
    • Arctische Pinguin
Re: Sea Ice Extent around Antarctica
« Reply #719 on: September 15, 2017, 06:10:35 PM »
Detailed graphs of extent and area calculated from NSIDC NT sea ice concentration attached. I highlighted the 1986 curve as well: lowest extent and area minimum until this year...
Click for a bigger picture.
« Last Edit: September 15, 2017, 06:17:02 PM by Wipneus »

gerontocrat

  • ASIF Middle Class
  • Posts: 606
    • View Profile
Re: Sea Ice Extent around Antarctica
« Reply #720 on: September 18, 2017, 03:00:57 PM »
JAXA DATA
Sea ice extent now only 50,000 km2 above 2016, and at its lowest since 10 days ago.
More likely that the 18.062 million km2 extent on 12th September will be the maximum extent.
But wobbles in extent often persist until end of September before significant melt occurs.
"Para a Causa do Povo a Luta Continua!"

Pavel

  • ASIF Lurker
  • Posts: 99
    • View Profile
Re: Sea Ice Extent around Antarctica
« Reply #721 on: September 18, 2017, 09:50:35 PM »
A polynya have been opening in Atlantic side. The animation from 12 to 17 September. Also cold anomalies forecasted in the Ross sea