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Author Topic: Sea Ice Extent around Antarctica  (Read 96092 times)

gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #600 on: March 28, 2017, 02:35:02 PM »
Jaxa measurement of extent 27th March 2017 is 3,329,871 km2. This is 663,237 km2 (circa 17 %) less than the previous lowest figure for this date in 2006, and 37% below the average for this date in the 1980s. Antarctic sea ice extent has now been at or below previous record minimums for around 5 months. Current refreezing rates are below the average.

Anyone out there got ideas on what has changed since the record maximum in 2014 and whether one can speculate on a possible long-term sea change in the Antarctic ?

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Re: Sea Ice Extent around Antarctica
« Reply #601 on: March 28, 2017, 02:53:47 PM »
This is 663,237 km2 (circa 17 %) less than the previous lowest figure for this date in 2006,

A)  17% BELOW the prior record is A BUNCH.

B)  Do you know what the % drop is from LAST YEAR at this time?  I assume slightly more than 17%....but would be curious to know if you have that figure....thanks.



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gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #602 on: March 28, 2017, 03:49:30 PM »
This is 663,237 km2 (circa 17 %) less than the previous lowest figure for this date in 2006,

A)  17% BELOW the prior record is A BUNCH.

B)  Do you know what the % drop is from LAST YEAR at this time?  I assume slightly more than 17%....but would be curious to know if you have that figure....thanks.

I knew I should have double-checked. The 37 % drop is compared with 2016. (The drop compared with the 1980s (the decade with the lowest extent) is a mere 29 percent). The drop compared with 27 March 2015 is 44 percent. The change in the last two years has been lunatic. Mais pourquoi ?

Buddy

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Re: Sea Ice Extent around Antarctica
« Reply #603 on: March 28, 2017, 04:17:24 PM »
Mais pourquoi ?

Yes....why indeed.  As I noted in my "rant" with the two graphs.....it could be several things combined.  All I know....is the facts that I see.

And 17% below the all time record is a LOT......and a 37% drop compared to last year is off the charts.  As a NON SCIENTIST....but an analyzer of facts and figures....I would first look at the OCEAN (continually increased warming) AND any change in currents as I noted before.  Certainly....my untrained scientific eye would look at the El Nino and its after effects as well.

The thing with global warming....is there are SO MANY THINGS THAT ARE CONSTANTLY CHANGING.....that it must be a real devil to ferret out what the current causes are....because ALL the causes/changes effect each other to some extent.

Thanks for getting that number by the way....
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oren

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Re: Sea Ice Extent around Antarctica
« Reply #604 on: March 28, 2017, 05:01:16 PM »
The main difference from previoues years is the Ross Sea. Other seas are within the historic variance, though on the low side. Not sure what happened there, I used to think it was some Pacific teleconnection from the monster El-Nino, not sure anymore. If next year repeats the same performance in Ross, it will be even more interesting.

crandles

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Re: Sea Ice Extent around Antarctica
« Reply #605 on: March 28, 2017, 05:16:23 PM »
Currently 3.33 vs 3.99 for 2006 & 2011 16.5% down 0.66 m km2 down

6 March 2017 2.2 vs 2.68 for 2006 18% down 0.48 m km2 down

15 Dec 2016 8.05 vs 9.46 for 2005 15% down 1.41 m km2 down

16.5% down on record low is not quite a record amount in % terms, as reached 18% down on previous record in early March. (Still the km2 is larger now.)

But in m km2 current 0.66 is small compared to December which reached 1.41 down.


Lord M Vader

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Re: Sea Ice Extent around Antarctica
« Reply #606 on: March 28, 2017, 06:37:42 PM »
I suggest that you read this section of NSIDC faq where they highlight an scientific study (Meehl, 2016) which claims that the switch in the PDO/IPO and El Niño as a possible reason for the changes we have seen so far.

http://nsidc.org/arcticseaicenews/faq/#wintertimeantarctic

Bill Fothergill

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Re: Sea Ice Extent around Antarctica
« Reply #607 on: March 29, 2017, 12:05:37 PM »
As the ASIF was down for some time, I originally posted the following comments on the current ASIB thread instead.

Every day since the 5th November 2016, Antarctic sea ice extent has been at record low levels. The NSIDC daily Antarctic sea ice extent value for March 27th came in at 3.304 million sq kms. This was a somewhat jaw-dropping 2.037 million sq kms lower than the equivalent figure from last year.

The cumulative effect of just over 20 weeks at record low levels has obviously been dragging down the rolling 365-day annual average extent figure. In fact, for the last 5 days, this average extent value has been dropping at over 5k sq kms each day.

The latest (as at 27th March) rolling 365-day average extent value has now dropped to 10.966 million sq kms. The previous record low average was 10.969 million sq kms (6th Aug 1979 - 4th Aug 1980).

To give a bit more perspective, decadal averages (calculated from the NSIDC monthly values) come out as...

1980-89 11.82 million sq kms
1990-99 12.03 million sq kms
2000-09 12.18 million sq kms
2010-16 12.46 million sq kms

Several weeks ago, on the relevant ASIF thread, I had been demonstrably cautious when I had suggested that the rolling 365-day figure would drop below 11 million sq kms by the end of March, and could likely surpass the previous record low sometime toward the end of April.

CAVEAT: Prior to the 20th Aug 1987, figures were produced on alternate days. Therefore, during that earlier record low period (1979-1980), the rolling 365-day figure actually comprised just 183 data points. The implicit assumption is, of course, that the "missing" days will, on average, tend to be halfway between the before/after dates. Some will be lower, some will be higher, but this should just about even out over the 182 "missing" days.



As LMV has just pointed out yet again (see also his comment #585, and my #583 and #587) there are good scientific reasons behind this latest twist in the Antarctic sea ice saga.


gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #608 on: March 29, 2017, 12:23:25 PM »
Archaeologists, when they are on a dig, say one needs three bricks before one can say for definite one has found a wall. When I look at the collapse in antarctic sea ice over the last 2 1/2 years, I think I only see one brick, as variability of extent is so high in the satellite record.

Perhaps one needs another two years of consistently extremely low sea ice extent before asking if  natural variation is being supplemented by AGW having penetrated the wall of Antarctic's isolation.

Meanwhile, did the extremely low sea ice this year allow significant impacts on any of the ice shelves ?

Buddy

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Re: Sea Ice Extent around Antarctica
« Reply #609 on: March 29, 2017, 12:36:27 PM »
When I look at the collapse in antarctic sea ice over the last 2 1/2 years, I think I only see one brick, as variability of extent is so high in the satellite record.

That 2 and 1/2 year period may only be "one brick"......but it happens to be about the 30th brick, not the first if you're looking long term.  If you're looking intermediate term (from 2007)....then it is about the 3rd or 4th brick.

IF you are JUST talking about the Antarctic sea ice level.....without looking at the Arctic or looking at the other "things" related in a BROADER SENSE....then I can understand what you are trying to say.  BUT....putting in a context of what is happening in Arctic, Greenland, feedback effects, etc....THAT is why I would "broaden" the context.

And....it certainly makes the current 12 month period extremely interesting regarding the Antarctic...because IF this year also ends up like the past year....it will certainly heighten the concern of most everyone.
« Last Edit: March 29, 2017, 12:43:05 PM by Buddy »
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Bill Fothergill

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Re: Sea Ice Extent around Antarctica
« Reply #610 on: March 29, 2017, 01:24:22 PM »
... When I look at the collapse in antarctic sea ice over the last 2 1/2 years ...

It's not even as long as that. NSIDC's 5-day Charctic feature tells us that , as recently as July 12th 2015, Antarctic extent was at a record high for the date. The average extents for March 2016 and April 2016 currently rank 24th and 25th lowest (out of 38) respectively. {Soon to become 25th and 26th respectively out of 39.}

As every month from July 2012 to July 2015 (inclusive) had an average extent which was in the highest quartile, we most assuredly need more data in order to see if the behaviour over the last 7 months will prove to be a genuine "state change", or whether it is nothing more than a chimera - albeit an interesting one.

Your concern over the impact on the shelves is shared. I am looking forward (although with some trepidation) to flow-rate data from the British Antarctic Survey regarding places such as Thwaites and P.I.G.

LMV has, on more than one occasion, provided a link to the NSIDC's FAQ which deals with Antarctic variability, and it is well worth the read.
http://nsidc.org/arcticseaicenews/faq/#wintertimeantarctic

Bill Fothergill

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Re: Sea Ice Extent around Antarctica
« Reply #611 on: March 29, 2017, 01:56:36 PM »
NSIDC has just published the data for 28th March.

The daily value jumped a less-than-impressive 53k sq kms to 3.357 million sq kms. This is now 2.082 million sq kms less than this time last year.

The rolling 365-day dropped 5.7k sq kms to 10.96 million sq kms. On the 30th April 2016, this particular metric stood almost exactly one million sq kms higher at 11.96 million sq kms. Since the 28th Feb 2017, it has dropped almost exactly 100k sq kms.

NSIDC should publish their monthly figures by about the 2nd April, and I will be paying particular attention to area, as that looks even worse.

gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #612 on: March 31, 2017, 01:58:31 PM »
Dear Bill, (shades of Private Eye from the Thatcher years ?)

Thanks for reminder to look at NSIDC's comments on Antarctic sea ice extent. They aren't really sure themselves, are they ? Looked at the PDO history and compared the index with various lows (1980, 2006) and highs 2014-2015, and couldn't see much correlation. (Mind you, too damn lazy to plug in the two sets of data and let excel do the math). So I remain adrift, unable to even have an opinion to be shot down (or Dinged?).

So nowt to do but wait and see. Will antarctic sea ice persist in staying at a record low, or will the wiggly line drift back into the ruck. (Note that 2006 no longer the lowest - it is 1980 that is the outlier until the end of May).

Sometimes watching slow-motion train wrecks is a real drag.

Charctic on NSIDC says that the 28th March extent was 3.205 m km2, the 29th 3.278 m km2 and the 30th 3,353 m km2. i.e. increase of circa 75,000 km2 per day, still a bit below the average daily increase for the time of year.

Bill Fothergill

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Re: Sea Ice Extent around Antarctica
« Reply #613 on: March 31, 2017, 08:16:30 PM »
Thanks for reminder to look at NSIDC's comments on Antarctic sea ice extent.

I've just re-read my #610 and it might appear that I was aiming that reminder specifically at you. Apologies if that's how it seemed. It was meant as a sort of general throw-away line, and I should have made this more clear.

gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #614 on: April 03, 2017, 04:23:36 PM »
Jaxa extent for 2nd April is 3,784,646 km2, still 1.4 million km2 below the 1980's average.

The wiggly line continues to boldly go where no wiggly line has been before.
Or,
literally in uncharted territory.



gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #615 on: April 06, 2017, 11:36:11 AM »
Jaxa extent for 2nd April is 3,784,646 km2, still 1.4 million km2 below the 1980's average.

The wiggly line continues to boldly go where no wiggly line has been before.
Or,
literally in uncharted territory.

Whereupon in just 3 days sea ice extent increases by 440,300 km2 to 4,224,946 km2.

RikW

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Re: Sea Ice Extent around Antarctica
« Reply #616 on: April 06, 2017, 12:07:45 PM »
that's not extremely much, on average it should increase with around 9 million m2 between mid march and mid june, so on average 100k/day, with the increase a little higher on the first half compared to the 2nd half

Gray-Wolf

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Re: Sea Ice Extent around Antarctica
« Reply #617 on: April 11, 2017, 04:37:32 PM »
Archaeologists, when they are on a dig, say one needs three bricks before one can say for definite one has found a wall. When I look at the collapse in antarctic sea ice over the last 2 1/2 years, I think I only see one brick, as variability of extent is so high in the satellite record.

Perhaps one needs another two years of consistently extremely low sea ice extent before asking if  natural variation is being supplemented by AGW having penetrated the wall of Antarctic's isolation.

Meanwhile, did the extremely low sea ice this year allow significant impacts on any of the ice shelves ?

Were we not expecting a change in Sea ice cover around Antarctica then we might say that but we know the Ozone forcing is now on the wane , year on year, and the Pacific naturals flipped to support a 'less ice' set up back in 2014.

I agree we need more bricks but geophysical says there's a wall there so do not be surprised when one turns up and we see 30 years of 'catchup' going on as Shelfs respond to higher energy summers with open water providing much more 'waggle factor' to the floating extensions!
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Lord M Vader

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Re: Sea Ice Extent around Antarctica
« Reply #618 on: April 11, 2017, 07:25:09 PM »
The SIE around Antarctica have increased significantly during the last week or so and is now more or less equal with 1980. It seems reasonable to believe that 2017 won't be lowest on record in a few days or so as the spatial distribution of the se differs quite a lot between 1980 and 2017.

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Re: Sea Ice Extent around Antarctica
« Reply #619 on: April 12, 2017, 01:12:15 PM »
The SIE around Antarctica have increased significantly during the last week or so and is now more or less equal with 1980. It seems reasonable to believe that 2017 won't be lowest on record in a few days or so as the spatial distribution of the se differs quite a lot between 1980 and 2017.
I'm curious as to whether that indicates ongoing basal melt and the spread of easy to freeze fresh water and if that's the case what implications it has for future ice loss.

Bill Fothergill

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Re: Sea Ice Extent around Antarctica
« Reply #620 on: April 12, 2017, 06:57:48 PM »
The SIE around Antarctica have increased significantly during the last week or so and is now more or less equal with 1980. It seems reasonable to believe that 2017 won't be lowest on record in a few days or so ...


And, as if by magic...



nicibiene

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Re: Sea Ice Extent around Antarctica
« Reply #621 on: April 13, 2017, 09:29:34 AM »
I'm curious as to whether that indicates ongoing basal melt and the spread of easy to freeze fresh water and if that's the case what implications it has for future ice loss.

I assume it could be caused by more meltwater available. Just wanted to check the massloss and wonder again why some official available datas quit at a certain point... here datas from https://data1.geo.tu-dresden.de/ais_gmb/

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Bill Fothergill

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Re: Sea Ice Extent around Antarctica
« Reply #622 on: April 13, 2017, 10:35:22 AM »
The SIE around Antarctica have increased significantly during the last week or so and is now more or less equal with 1980. It seems reasonable to believe that 2017 won't be lowest on record in a few days or so ...


And, as if by magic...
On the other hand, the ADS data shows that 2017 is still chilling out on the low side of 1980.

However, the fact that 1980 was a leap year means that, when doing a comparison between the two years, a one-day discontinuity gets introduced into the day number/date after 28th Feb 2017.

Additionally, there is a 7-day gap in the data (9th to 15th April 1980) and therefore ADS have, quite reasonably, used a linear interpolation between the 8th and 16th April 1980. That means 1980 could have been lower at today's date.

Irrespective of the above, the point is somewhat moot; to all intents and purposes, the sea ice extent levels (although not necessarily the distribution/concentration) are currently virtually identical with those measured 37 years ago. Given the extreme variability demonstrated in the past, I have absolutely no opinion on whether 2017 will still have the lowest level in a week, or, for that matter, in a month, or three months or at the maximum.


On the other, other, hand, things are a bit clearer as regards any rolling 365-day average. The ADS data now shows the current 365 day average extent as being around 230K sq kms lower than the previous lowest value clocked up in 1980. The NSIDC numbers are a bit more modest, but still show this metric as ~ 85k sq kms lower than the lowest recorded during 1980.

(NB Both ADS and the NSIDC show this metric still dropping at just over 4k sq kms/day. That means, when the NSIDC data for Day-102 becomes available, the rolling average will drip to ~90k sq kms below the previous record.)



johnm33

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Re: Sea Ice Extent around Antarctica
« Reply #623 on: April 13, 2017, 11:15:39 AM »

nicibiene

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Re: Sea Ice Extent around Antarctica
« Reply #624 on: April 13, 2017, 12:14:27 PM »
Quite impressive that blue spot at West Antarctica.  :o

Interesting also if you watch the massloss of the Western Antarctica Icesheet-especially in winter mass loss continues... and it would have been interesting to have more datas from July 2016 on.

But they stopped with public datas...why?  >:(

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gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #625 on: April 13, 2017, 02:43:32 PM »
The 1980s was the decade with the lowest Antarctic Sea Ice. Despite losing its lowest ever place to 1980, Antarctic Sea Ice extent as measured by Jaxa is still more than 1.3 million km2 (20 %) below the 1980s average. ( 1980 itself was a real outlier). So my one brick out of three is still intact - maybe something is stirring in the Antarctic.

Will there be data on any impact of the record low sea ice in the Austral summer on the ice shelves ?

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Re: Sea Ice Extent around Antarctica
« Reply #626 on: April 13, 2017, 03:49:28 PM »
Sea ice area calculated from NSIDC sea ice concentration is second place too, but  closer to become third. Here are the rankings bottom four:

extent SH
2006-04-12 5.639845
1981-04-12 5.505485
2017-04-12 5.008667
1980-04-12 4.937324

area SH
2006-04-12 3.960018
1981-04-12 3.760847
2017-04-12 3.609386
1980-04-12 3.371592

Graphs attached ( with leap year offsets compensated by aligning the data to the true solar equinoxes).

Bill Fothergill

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Re: Sea Ice Extent around Antarctica
« Reply #627 on: April 13, 2017, 07:10:29 PM »
The "lowest 4 as at 12th April" provided by Wipneus gives some insight as to the ridiculous intra-year (never mind inter-year) variability exhibited in the Antarctic.

The years 1980, 1981 and 2006 each feature in that "lowest 4", so let's play a quick game of "guess what happened next".

Using the NSIDC monthly figures for area, we see that...

1980 is currently lowest for April, May and June, and 2nd lowest for July. However, by October, it had slipped out to 33rd of 38.

In April and May of the following year, 1981, sea ice area was back down to 2nd lowest, but promptly shot back up to 29th by October, and 34th (of 39) by November.

2006 is 3rd lowest for April and 5th lowest for May, but then ends up with 33rd, 34th and 36th for August, September and October, respectively.

These years are by no means outliers in this respect; 2000, 2001 and 2002, to name just a few, also exhibit such extreme variability.

Bill Fothergill

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Re: Sea Ice Extent around Antarctica
« Reply #628 on: April 14, 2017, 10:17:06 AM »
I'm curious as to whether that indicates ongoing basal melt and the spread of easy to freeze fresh water and if that's the case what implications it has for future ice loss.

You may find some material of interest if you have a little trawl through the British Antarctic Survey site.

For example, there was a brief press release last year concerning the impact of warming waters...
https://www.bas.ac.uk/media-post/ocean-warming-primary-cause-of-glacier-retreat/

There is also an abundance of metadata at...
https://data.bas.ac.uk/datasets.php?topic=Cryosphere&term=Glaciers%2FIce+Sheets

gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #629 on: April 21, 2017, 01:12:59 PM »
As of April 20th Jaxa measure of extent is 5,889,051, a large 167,000 km2 increase in a day. Average April per day increase is 112,000, also a bit higher than normal (?what normal?). Still 2nd lowest extent in satellite record (NSIDC Charctic), and still over 1 million km2 below 1980s average.

Jaxa also still showing strong sea ice drift away from Antarctica in Ross and Weddell seas.

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Re: Sea Ice Extent around Antarctica
« Reply #630 on: April 24, 2017, 01:39:39 PM »
Quite warm in Antarctica too at the moment....

Also a remarkable anomalies in albedo warming potential- here a site with compairision of several years:
https://sites.google.com/site/cryospherecomputing/warming-potential/Albedo-Warming-Overview
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Bill Fothergill

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Re: Sea Ice Extent around Antarctica
« Reply #631 on: April 24, 2017, 09:03:05 PM »
Quite warm in Antarctica too at the moment....

Also a remarkable anomalies in albedo warming potential- here a site with compairision of several years:
https://sites.google.com/site/cryospherecomputing/warming-potential/Albedo-Warming-Overview

That site is run by Nico Sun, who posts on the ASIF under the handle of "Tealight".

Here is the link to his thread on Albedo Warming Potential...

http://forum.arctic-sea-ice.net/index.php/topic,1749.0.html

rboyd

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Re: Sea Ice Extent around Antarctica
« Reply #632 on: April 28, 2017, 09:02:24 PM »
2014 = -28.22 kWh/M2 (yes, negative)
2015 = -21.56 kWh/m2 (yes, negative)
2016 = +12.96 kW in 2006 (flip to positive)
2017 = +59.549 kWh/m2

A turn around of nearly 90 kWh/m2 in 4 years, that's a lot of extra heat being taken into the southern ocean. The start of "Antarctic Amplification"?
« Last Edit: April 28, 2017, 09:10:47 PM by rboyd »

gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #633 on: May 02, 2017, 03:19:01 PM »
Sea ice extent per Jaxa on 1st May 7,100,141, somewhat lower per day extent increase over the last few days despite strong outward sea ice drift in Weddell  and Ross seas.

Jaxa sea ice drift for antarctica also somewhat spectacular today:-
- https://ads.nipr.ac.jp/vishop.ver1/vishop-monitor.html?S

And from the weather-forecast.com link  below one can see where the name "The Furious Fifties" came from to describe the Southern Antarctic Ocean. I would not want to be on anything that floats down there at the moment.

http://www.weather-forecast.com/maps/Antarctica?over=pressure_arrows&symbols=none&type=wind




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Re: Sea Ice Extent around Antarctica
« Reply #634 on: May 22, 2017, 06:12:42 PM »
Extent and area growth have slowing or even reversing, at least by the NSIDC sea ice concentration.

Both area and extent still occupy 2nd lowest place. Moving closer to 1980.

extent SH
1990-05-21 10.225472
2007-05-21 10.199011
1987-05-21 10.163478
2002-05-21 10.006257
2006-05-21 9.979037
1981-05-21 9.932460
1983-05-21 9.921044
1986-05-21 9.887104
2017-05-21 9.565976
1980-05-21 9.449800

area SH
1987-05-21 7.916975
1984-05-21 7.913605
2002-05-21 7.747078
1988-05-21 7.607524
1986-05-21 7.580002
2006-05-21 7.561909
1981-05-21 7.516775
1983-05-21 7.369399
2017-05-21 7.064158
1980-05-21 6.901739

gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #635 on: May 22, 2017, 06:55:34 PM »
Hullo Wipneus,
I was waiting to see if the last 2 days jaxa nos were just a blip. If they are not, time once again to wonder what the hell is goi g on down there ?

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Re: Sea Ice Extent around Antarctica
« Reply #636 on: May 23, 2017, 03:01:06 PM »
If seen by NSIDC, Jaxa, U-Hamburg products the dip is real.
 
Area has partly recovered again today, without affecting rankings.  That is life for the followers of the day-to-day changes.


gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #637 on: May 24, 2017, 02:27:17 PM »
Given the very strong sea ice drift around Antarctica, the marked reduction in refreezing rates in the last 4 days may be a temporary blip.(63,000 km2 per day cf 135,000 per day in the previous 10 days).
Nevertheless, it remains that from Early Nov 2016 to early April 2017, a period of over 150 days, sea ice extent (per Jaxa) was the lowest in the satellite record, and since then (a period of over 40 days) sea ice extent has been and remains second lowest, (nearly 1 million km2 lower than the 1980s average).

Significant ? Je ne sais pas. Worth keeping an eye on ? Methinks yes.


gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #638 on: May 30, 2017, 03:49:29 PM »
On May 27 the Jaxa extent measure become more than 1 Crore m2. (Now at 10.3 million m2).
According to NSIDC's Charctic graph, also moved from 2nd to third lowest, though returning to 2nd lowest or lowest is very possible in the next few days. Is also currently 987,000 km2 (8.7%) below the 1980s average.
Sea ice drift out northwards from Ross and Weddell seas remains impressive.

Lord M Vader

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Re: Sea Ice Extent around Antarctica
« Reply #639 on: May 30, 2017, 05:41:55 PM »
And the lack of sea ice in West Antarctica is equally impressive!

gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #640 on: June 10, 2017, 02:15:54 PM »
And the lack of sea ice in West Antarctica is equally impressive!

Antarctic sea ice extent (Charctic image) seems to be still 3rd lowest (just). But (Jaxa data) only 0.5 million km2 less than the 1980's average compared with a max of 1.4 million km2 earlier in the year.
This difference is almost entirely confined to West Antarctica.

gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #641 on: June 17, 2017, 12:13:04 PM »
Antarctic sea ice extent still seems to be third lowest (from Charctic), (and from Jaxa) 0.7 million km2 (5.5%) below the 1980's average, and 2 million km2 (14% 19 days ) below 2014 (maximum year).

So no real change in this persistent low extent. But is it the case of the dog that did not bark? One can do nowt but wait.

Wipneus

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Re: Sea Ice Extent around Antarctica
« Reply #642 on: June 17, 2017, 06:37:43 PM »
Yes, with area the position is 6th lowest. Note that 2016 was at this date late year nowhere near the bottom 10 yet.

extent SH
1995-06-16 13.111516
1993-06-16 13.081682
1997-06-16 13.059745
1992-06-16 12.840877
1983-06-16 12.797465
1987-06-16 12.789769
1980-06-16 12.766877
2017-06-16 12.548448
1986-06-16 12.541214
2002-06-16 12.363365

area SH
1997-06-16 10.082896
1992-06-16 10.069927
1995-06-16 10.012473
1987-06-16 9.998876
2017-06-16 9.883237
1991-06-16 9.866560
1983-06-16 9.826909
1980-06-16 9.808612
2002-06-16 9.718470
1986-06-16 9.363011

gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #643 on: June 17, 2017, 06:49:35 PM »
Hullo wipneus,
I looked at NSIDC to find Antarctic sea ice spreadsheets and only found Arctic. Alcohol may have been involved. It is all because in my head there are 3 things of which we humans are most ignorant of re planet earth of which no #1 is the Antarctic. Imagine I am a bloodhound, give me a rag to scent and I will be on the hunt.

Regards,

Gerontocrat.



gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #644 on: June 22, 2017, 02:50:46 PM »
In the last 5 days sea ice extent has increased by an average of 62,000 km2 per day, 45% less than the average increase since April 1.(JAXA data). However, it does seem that much of the difference in daily changes can be attributed to the strength and direction of sea ice drift, in itself a function of the violent weather down there.

Nevertheless sea ice extent in Antarctica according to NSIDC's Charctic is now tied with 2002 as lowest in the satellite record. Extent is nearly 1 million below that of the 1980's. Antarctic Sea Ice extent has been lowest, 2nd lowest and briefly 3rd lowest for some 225 days (since early Nov 2016).
Is this of note?


gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #645 on: June 27, 2017, 03:02:18 PM »
Antarctic Sea Ice Extent remains lowest in satellite record (Jaxa and NSIDC). Low daily increases in extent seem once again to be mostly due to strong sea ice drift parallel to coast and onshore.

Lord M Vader

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Re: Sea Ice Extent around Antarctica
« Reply #646 on: June 27, 2017, 05:22:43 PM »
The negative anomaly is entirely related to West Antarctica. Will be interesting to see if the sea ice will catch up with other years later this season.

gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #647 on: June 27, 2017, 08:01:42 PM »
The negative anomaly is entirely related to West Antarctica. Will be interesting to see if the sea ice will catch up with other years later this season.
In a month or two those gentle curves on the graph go all wobbly until melt sets in again. Maybe difficult to see any real trend until that melt gets going?

gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #648 on: June 28, 2017, 12:34:21 PM »
Here are some numbers. (I like numbers).

Jaxa data as at June 27
      
Extent in km2    13,327,296
   
Compared with:-    Difference    
                                   km2    %
2014 (max year)   -2,499,716   -16%
2015                   -2,119,571   -14%
2016                   -1,041,200   -7%
1980's (min yrs)   -1,024,239   -7%

And it is still all about West Antarctica.