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Author Topic: Global sea ice area and extent data  (Read 102210 times)

gerontocrat

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Re: Global sea ice area and extent data
« Reply #450 on: April 04, 2019, 08:29:07 AM »
JAXA Global Sea Ice Extent as at 3 April 2019 :-  17,577,832 km2

Global Sea Ice Extent on this day is 2nd lowest, above 2017.Average Antarctic gain + average Arctic loss on this day.

- extent gain on this day 58k,  5k less than the the average gain of 63 k on this day,
- extent gain from minimum to date is 1,330k, 1,540k (54%) less than the average gain of 2,870k,
-on average 31.8% of extent gain done and 215 days to maximum ( 4-Nov),

The Perils of Projections
- last 10 years average remaining extent gain would give a maximum of 23.73 million km2,  95k more than the record low max of 2016 and 2nd lowest in the satellite record. Tomorrow 2017 extent gain were very high, so there is a good chance that then 2019 will be lowest in the satellite record, even if only for one day.
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oren

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Re: Global sea ice area and extent data
« Reply #451 on: April 04, 2019, 02:23:29 PM »
In 6 weeks it went from 0.4M to 2M km2 below the 2010s average. System volatility is certainly increasing.

Stephan

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Re: Global sea ice area and extent data
« Reply #452 on: April 05, 2019, 07:56:22 AM »
A smaller increase (as Average) in Antarctic and a larger decrease (as average) in the Arctic today led to a new record low in global sea ice, as "announced" by several people here in this forum. Today it came true.

gerontocrat

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Re: Global sea ice area and extent data
« Reply #453 on: April 05, 2019, 12:58:33 PM »
JAXA Global Sea Ice Extent as at 3 April 2019 :-   17,592,526 km2

Continuing Antarctic extent gain at or a bit below average and Arctic extent loss continuing at above average,  has resulted in Global Sea Ice Extent on this day being lowest. Another line being written on a previously unused part of the graph paper.

- extent gain on this day 15k,  42k less than the the average gain of 57 k on this day,
- extent gain from minimum to date is 1,340k, 1,580k (54%) less than the average gain of 2,930k,
-on average 32.4% of extent gain done and 214 days to maximum ( 4-Nov),

The Perils of Projections
- last 10 years average remaining extent gain would give a maximum of 23.69 million km2,  53k more than the record low max of 2016 and 2nd lowest in the satellite record.
____________________________________________________________________________
From now on only occasional updates unless unusual stuff going on. But maybe unusual is the new normal.
"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)

gerontocrat

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Re: Global sea ice area and extent data
« Reply #454 on: April 06, 2019, 08:55:43 AM »
JAXA Global Sea Ice Extent as at 5 April 2019 :- 17,670,997 km2

Until this day, continuing Antarctic extent gain at or a bit below average and Arctic extent loss continuing at above average,  has resulted in Global Sea Ice Extent on this day being lowest. Another line being written on a previously unused part of the graph paper.

- extent gain on this day 78k,  22k more than the the average gain of 56 k on this day,
- extent gain from minimum to date is 1,420k, 1,560k (52%) less than the average gain of 2,980k,
-on average 33.1% of extent gain done and 213 days to maximum ( 4-Nov),

The Perils of Projections
- last 10 years average remaining extent gain would give a maximum of 23.71 million km2,  75k more than the record low max of 2016 and 2nd lowest in the satellite record.
____________________________________________________________________________
From now on only occasional updates unless unusual stuff going on. But maybe unusual is the new normal.
"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)

Stephan

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Re: Global sea ice area and extent data
« Reply #455 on: April 07, 2019, 08:52:21 AM »
I compared the actual JAXA extent value (April 6) of Arctic and Antarctic with the decadal averages of the 10s, 00s, 90s, and 80s and calculated the cumulative difference of 2019 (example: in the Arctic we are 20 days ahead compared to the 10s, in the Antarctic we are 11 days behind the 10s average, which sums up to 31 days, almost a month).
Compared to earlier decades this difference is even bigger:
April 6, 2019 vs. 00s: 42 days
April 6, 2019 vs. 90s: 50 days
April 6, 2019 vs. 80s: 59 days (almost two months)
So there is a big difference as there is less ice to melt in the Arctic this coming melting season (so less energy needed) and more ice to form in the Antarctic this coming freezing season (more freezing energy to be released). In addition you must also take the Albedo effect into account.

b_lumenkraft

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Re: Global sea ice area and extent data
« Reply #456 on: April 07, 2019, 10:15:40 AM »
I compared

You are having a way to look at the data in such a unique way, i'm always impressed. Compare on sir!

magnamentis

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Re: Global sea ice area and extent data
« Reply #457 on: April 07, 2019, 01:33:33 PM »
I compared the actual JAXA extent value (April 6) of Arctic and Antarctic with the decadal averages of the 10s, 00s, 90s, and 80s and calculated the cumulative difference of 2019 (example: in the Arctic we are 20 days ahead compared to the 10s, in the Antarctic we are 11 days behind the 10s average, which sums up to 31 days, almost a month).
Compared to earlier decades this difference is even bigger:
April 6, 2019 vs. 00s: 42 days
April 6, 2019 vs. 90s: 50 days
April 6, 2019 vs. 80s: 59 days (almost two months)
So there is a big difference as there is less ice to melt in the Arctic this coming melting season (so less energy needed) and more ice to form in the Antarctic this coming freezing season (more freezing energy to be released). In addition you must also take the Albedo effect into account.

a cumulation of time to express energy is interesting, nevertheless and even though i got your point and agree, those days are kind of overlapping (timewise) and hence should not be cumulated and used to express energy needed to melt or freeze.

if at all one could perhaps take an average between SH and NH to express an average of such kind but again, cumulation of those days are a bit abstract and can lead to misinterpretation.

to avoid such misunderstanding i repeat, i understand what you are trying to convey and i agree to your thoughts and often think about that the exact same way.

of course and as always, in case i'm to one who missed a point here, don't hesitate to enlighten me and/or elaborate further, the above just came to my mind while reading.

for the rest what others have said, generally interesting to read your various contributions  :)

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gerontocrat

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Re: Global sea ice area and extent data
« Reply #458 on: April 08, 2019, 12:13:12 PM »
JAXA Global Sea Ice Extent as at 7 April 2019 :- 17,820,478 km2

For two brief days (4-5 April) extent was lowest. But then high Antarctic gain outweighed above average Arctic loss, so extent is now 22k above 2017.

- extent gain on this day 90k,  13k more than the the average gain of 78 k on this day,
- extent gain from minimum to date is 1,420k, 1,560k (52%) less than the average gain of 2,980k,
-on average 34.7% of extent gain done and 211 days to maximum ( 4-Nov),

The Perils of Projections
- last 10 years average remaining extent gain would give a maximum of 23.71 million km2,  75k more than the record low max of 2016 and 2nd lowest in the satellite record.
____________________________________________________________________________
From now on only occasional updates unless unusual stuff going on. But maybe unusual is the new normal.
[/quote]
"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)

gerontocrat

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Re: Global sea ice area and extent data
« Reply #459 on: April 13, 2019, 10:21:26 AM »
JAXA Global Sea Ice Extent as at 12 April 2019 :-  18,259,037 km2

In recent days extent gain has been at or a bit above average, so extent is now 125k above 2017.

- extent gain on this day 94k, 17k more than the the average gain of 77 k on this day,
- extent gain from minimum to date is 2.01 million km2, 1.53 million km2 (43%) less than the average gain of 2.54 milllion km2,
-on average 39.2% of extent gain done and 206 days to maximum ( 4-Nov),

The Perils of Projections
- last 10 years average remaining extent gain would give a maximum of 23.74 million km2,  108k more than the record low max of 2016 and 2nd lowest in the satellite record.
____________________________________________________________________________
From now on only occasional updates unless unusual stuff going on. But maybe unusual is the new normal.
"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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Killian

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Re: Global sea ice area and extent data
« Reply #460 on: April 14, 2019, 12:13:03 PM »
Re: Historic ASI Extent, Daily Records
(Don't know if this is the best place to post this, so if not, please move.)

I was looking at recent years' new records being in mind of my Aug 2015 prediction of new record ASI lows or near record lows for 2016-17 period (two years follwing an El Nino.) 2016 was the second lowest, as we all know. However, it also had extensive new records in the spring and fall months. since 2015, I've always wondered if these numbers of total record days might have some sort of important or useful data embedded, but have never checked.

Today I was poking around and got curious how often new daily records are set year-on-year. Using JAXA's interactive chart I got a rather startling surprise. Using 1979 as the baseline, every single year has had a least a few daily record lows. Every. Year.

That, to me, is unexpected. I just never thought about it, but see it as making the overall trend more robust than it seems just from the yearly low trend.

How many years set new yearly lows using '79 as the baseline (though it seems likely to have been lower than '78)?

'84 (5 yrs)
'85 (1 yr)
'90 (5 yrs)
'95 (5 yrs)
'99 (4 yrs)
'02 (3 yrs)
'05 (3 yrs)
'07 (2 yrs)
'12 (5 yrs)

Currently six years since the last new low. Interestingly, the shorter periods of new lows was indicative of stability, with relatively small changes giving us new lows with the downward trend. then '07 and '12 changed things a lot, with '12 clearly being really anomalous. Of course, both those last years had the dipole set up blowing ice out Fram Strait.

Short version: We consistently had new ASI summer lows since we started tracking this.

gerontocrat

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Re: Global sea ice area and extent data
« Reply #461 on: April 20, 2019, 07:26:15 AM »
JAXA Global Sea Ice Extent as at 19 April 2019 :- 18,620,041  km2

In recent days extent gain more below than above average, so extent is now lowest for the 10th day this year, 135k below 2017.

- extent gain on this day 25k, 38k less than the the average gain of 63 k on this day,
- extent gain from minimum to date is 2.37 million km2, 1.41 million km2 (42%) less than the average gain of 4.09 milllion km2 by this day,
-on average 45.3% of extent gain done and 199 days to maximum ( 4-Nov),

The Perils of Projections
- last 10 years average remaining extent gain would give a maximum of 23.56 million km2,  78k less than the record low max of 2016 and lowest in the satellite record.
____________________________________________________________________________
From now on only occasional updates unless unusual stuff going on.
« Last Edit: April 20, 2019, 07:32:16 AM by gerontocrat »
"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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Stephan

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Re: Global sea ice area and extent data
« Reply #462 on: April 21, 2019, 08:43:18 AM »
I compared the actual JAXA extent value (April 20) of Arctic and Antarctic with the decadal averages of the 10s, 00s, 90s, and 80s and calculated the cumulative difference of 2019 (example: in the Arctic we are 14 days ahead compared to the 10s, in the Antarctic we are 11 days behind the 10s average, which sums up to 25 days).
Compared to earlier decades this difference is even bigger:
April 20, 2019 vs. 00s: 35 days
April 20, 2019 vs. 90s: 44 days
April 20, 2019 vs. 80s: 50 days
The big difference means that there is less ice to melt in the Arctic this coming melting season (so less energy needed) and more ice to form in the Antarctic this coming freezing season (more freezing energy to be released). In addition you must also take the Albedo effect into account.
The values are slightly smaller than on April 9 as the slope of the averages increase in May (higher melting rates than in April). But the general trend is unchanged. Climate change is on its way!

gerontocrat

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Re: Global sea ice area and extent data
« Reply #463 on: April 22, 2019, 08:10:29 AM »
JAXA Global Sea Ice Extent as at 21 April 2019 :- 18,620,041  km2

Extent gain continuing below average, so extent is now lowest for the 12th day this year, 289k below 2017.

- extent gain on this day 34k, 47k less than the the average gain of 81 k on this day,
- extent gain from minimum to date is 2.44 million km2, 1.79 million km2 (42%) less than the average gain of 4.24 milllion km2 by this day,
-on average 47.0% of extent gain done and 197 days to maximum ( 4-Nov),

The Perils of Projections
- last 10 years average remaining extent gain would give a maximum of 23.48 million km2,  157k less than the record low max of 2016 and lowest in the satellite record.
____________________________________________________________________________
From now on only occasional updates unless unusual stuff going on.
"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)

GoSouthYoungins

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Re: Global sea ice area and extent data
« Reply #464 on: April 26, 2019, 04:10:02 PM »
It is very telling that despite the record low global area, nobody posts on this thread for days. Record low is just the standard after the last 4 years and it is only really interesting in November when the record can get huge.
big time oops

Stephan

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Re: Global sea ice area and extent data
« Reply #465 on: April 26, 2019, 07:46:12 PM »
Five out of the eight lowest global sea ice extent values were achieved this decade. So "being low" seems to establish itself as the "new normal" (which is obviously sad).

Pmt111500

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Re: Global sea ice area and extent data
« Reply #466 on: April 27, 2019, 07:08:57 AM »
It is very telling that despite the record low global area, nobody posts on this thread for days. Record low is just the standard after the last 4 years and it is only really interesting in November when the record can get huge.

Rather I'd say that as this is a numerical product of two very weakly connected regions it's not as interesring as the Antarctic and Arctix separate ones. Sure there can be a connection between areas but this would take years or decades to notice. Rather unexciting compared to direct weather effects on each pole.
Amateur observations of Sea Ice since 2003.

gerontocrat

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Re: Global sea ice area and extent data
« Reply #467 on: April 27, 2019, 02:11:33 PM »
JAXA Global Sea Ice Extent as at 26 April 2019 :-  19,182,588  km2

Despite extent gain being mostly above average the last 5 days, extent still lowest for the 17th day this year, 12 days in a row, 243k below 2017.

- extent gain on this day 52k, 10k more than the the average gain of 42 k on this day,
- extent gain from minimum to date is 2.93 million km2, 1.58 million km2 (35%) less than the average gain of 4.52 milllion km2 by this day,
-on average 50.1% of extent gain done and 192 days to maximum ( 4-Nov),

The Perils of Projections
- last 10 years average remaining extent gain would give a maximum of 23.69 million km2,  52k more than the record low max of 2016 and lowest in the satellite record.
____________________________________________________________________________
From now on only occasional updates unless unusual stuff going on.
"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)

Rodius

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Re: Global sea ice area and extent data
« Reply #468 on: April 27, 2019, 02:29:46 PM »
I was 300k too high in my prediction that I believed was low and cheeky simply based on the merging the previous years.

I wonder if there is a physical reason for the trend of the last few years being so close?

magnamentis

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Re: Global sea ice area and extent data
« Reply #469 on: May 02, 2019, 07:35:34 PM »
global extent slowly but steadily is digging deeper into uncharted territory and nobody is paying attention, so many days without postings.

i've always advocated the opinion that we should pay way more attention to global developments because ultimately, the bigger the scale (the wider the angle to look at things) the more we can see when the sh.. hits the fan, means we can get a better feel about tipping points and irreversible changes.

heat, depending on currents, air and water, as well as depending on weather, is distributed much differently each year, each season and often short terms.

only a global look at temps and events and directions of development will give us a good feel as to what to expect as trends and speed of changes.

we're almost 10% below 2010 average, hence  global loss rate has vastly accelerated if we consider that we're down around 15% from 1980's average.

global sea ice is kind of a global refrigerator/cold-storage and 10% less ice globally must and will have a significant impact on the climate and since i look at sea-level rise as one of most matter of factual and inevitable effects of "global" warming this should trigger some very strong alarm bells, much stronger than the lack of attention in this thread would suggest.
« Last Edit: May 02, 2019, 07:45:11 PM by magnamentis »
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gerontocrat

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Re: Global sea ice area and extent data
« Reply #470 on: May 02, 2019, 08:34:48 PM »
JAXA Global Sea Ice Extent as at 1 May 2019 :-   19,253,124  km2

extent gain being below average the last 5 days, extent lowest for the 22nd day this year, 16 days in a row, 496k below 2017.

- extent gain on this day 19k, 34k less than the the average gain of 53 k on this day,
- extent gain from minimum to date is 3.00 million km2, 1.78 million km2 (37%) less than the average gain of 4.78 milllion km2 by this day,
-on average 53.1% of extent gain done and 187 days to maximum ( 4-Nov),

The Perils of Projections
- last 10 years average remaining extent gain would give a maximum of 23.49 million km2,  148k less than the record low maximum in 2016 and lowest in the satellite record.

Being a combination of two separate pieces of data volatility is often very high.
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From now on only occasional updates unless unusual stuff going on - or nudged by magnamentis
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Stephan

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Re: Global sea ice area and extent data
« Reply #471 on: May 02, 2019, 08:53:08 PM »
global extent slowly but steadily is digging deeper into uncharted territory and nobody is paying attention, so many days without postings.

...
I do pay attention:
I use a big whiteboard in my office and actualise the difference of Global Sea Ice Extent versus the average 2000-2009 on a daily basis (today e.g. 2.62 M km²). In addition I list the "top three" years (today 2019 - 2017 - 2018). After several weeks my colleagues started to pay attention and discuss climate change issues (most of them were not familiar at all with the global threat we are facing). Few of my colleagues neglect the facts, most of them are aware of the problems and choose little smart solutions for their daily lives.
I think all of us could do things like that to wake up the colleagues, friends and family members. Noone can save the world by themselves - but if everybody pays a little more attention (stairs vs. lift, bike vs. car, home-grewn vegetables instead of intercontinental import etc etc) the world could be a tiny little bit better  :D

magnamentis

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Re: Global sea ice area and extent data
« Reply #472 on: May 02, 2019, 09:54:19 PM »
global extent slowly but steadily is digging deeper into uncharted territory and nobody is paying attention, so many days without postings.

...
I do pay attention:
I use a big whiteboard in my office and actualise the difference of Global Sea Ice Extent versus the average 2000-2009 on a daily basis (today e.g. 2.62 M km²). In addition I list the "top three" years (today 2019 - 2017 - 2018). After several weeks my colleagues started to pay attention and discuss climate change issues (most of them were not familiar at all with the global threat we are facing). Few of my colleagues neglect the facts, most of them are aware of the problems and choose little smart solutions for their daily lives.
I think all of us could do things like that to wake up the colleagues, friends and family members. Noone can save the world by themselves - but if everybody pays a little more attention (stairs vs. lift, bike vs. car, home-grewn vegetables instead of intercontinental import etc etc) the world could be a tiny little bit better  :D

great and all true, i basically am aware that some do pay attention while my post was meant to provoke some more discourse over the matter which worked a little bit as it seems.

kind of knocking a few more sleepers out of the bush LOL
« Last Edit: May 03, 2019, 04:21:49 PM by magnamentis »
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b_lumenkraft

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Re: Global sea ice area and extent data
« Reply #473 on: May 03, 2019, 09:26:35 AM »
I think all of us could do things like that to wake up the colleagues, friends and family members.

So here is an anecdote:

My nephews birthday, talk about Greta Thunberg, my mother sais something about Greta doing this 'for the money'.
I'm pointing out the exact same issues for 30 years to her and i asked her when the last time was when she thought make this public and call for strikes is a great business model. Of course, she never thought of it and she did not answer and i bet she never had a second thought about my question.

This beautifully describes why i stopped trying to convince people a long time ago. When people trust some random facebook bots more than their own family members, what is there to do?

Neven

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Re: Global sea ice area and extent data
« Reply #474 on: May 03, 2019, 03:04:36 PM »
Has the max been reached?  ;)
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Stephan

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Re: Global sea ice area and extent data
« Reply #475 on: May 03, 2019, 04:02:28 PM »
hopefully not. If yes we are in catastrophic circumstances.

Tor Bejnar

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Re: Global sea ice area and extent data
« Reply #476 on: May 03, 2019, 04:06:46 PM »
If Neven suggests it, it must be true!  ::)
Arctic ice is healthy for children and other living things.

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Re: Global sea ice area and extent data
« Reply #477 on: May 03, 2019, 05:03:00 PM »
If Neven suggests it, it must be true!  ::)
This is an exciting conjecture! The posts on ocean currents spread so widely here I can't follow them all but Neven might! Well see how this goes, has ACC moved again a bit more south??
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oren

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Re: Global sea ice area and extent data
« Reply #478 on: May 03, 2019, 05:48:45 PM »
Seriously, we are still far from the spring maximum.

Juan C. García

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Re: Global sea ice area and extent data
« Reply #479 on: May 03, 2019, 06:39:06 PM »
Seriously, we are still far from the spring maximum.

Neven is joking...
But humanity should take the joke seriously!
Some year will happen.
Which is the best answer to Sep-2012 ASI lost (compared to 1979-2000)?
50% [NSIDC Extent] or
73% [PIOMAS Volume]

Volume is harder to measure than extent, but 3-dimensional space is real, 2D's hide ~50% thickness gone.
-> IPCC/NSIDC trends [based on extent] underestimate the real speed of ASI lost.

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Re: Global sea ice area and extent data
« Reply #480 on: May 03, 2019, 07:46:01 PM »
~6 weeks early would be an alarming data point, not a trend, just a single point!

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Re: Global sea ice area and extent data
« Reply #481 on: May 03, 2019, 08:56:46 PM »
Just for fun from jaxa, arctic only, data of May 2nd
years    average value    diminution   %           min value    difference   %
1980s13.9312.88-1.057.54%
1990s13.440.493.52%13.02-0.423.13%
2000s13.060.382.83%12.79-0.272.07%
2010s12.670.392.99%12.16-0.514.03%
« Last Edit: May 03, 2019, 09:02:50 PM by etienne »

bbr2314

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Re: Global sea ice area and extent data
« Reply #482 on: May 03, 2019, 10:42:21 PM »
Has the max been reached?  ;)
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kiwichick16

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Re: Global sea ice area and extent data
« Reply #483 on: May 04, 2019, 01:27:11 AM »
DON"T PANIC  !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

YET.

GoSouthYoungins

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Re: Global sea ice area and extent data
« Reply #484 on: May 04, 2019, 04:28:33 AM »
Don't be a moron. PANIC.
big time oops

sark

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Re: Global sea ice area and extent data
« Reply #485 on: May 04, 2019, 05:06:21 AM »
Don't panic?  The polar cell is acting funny.  Crops aren't getting planted.  The decline in nature is so fast now you can point it out in pictures.  The kids are in the streets because they stand to be destroyed, and nobody else has a clue. 

This was a structurally cold winter in a lot of ways, I think.  And the polar cell is doing tricks.  At 15C.  Like in 2016, like Now.

I am not a scientist

kiwichick16

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Re: Global sea ice area and extent data
« Reply #486 on: May 04, 2019, 05:40:41 AM »
@  Sark    ...we probably have years of stability yet.......perhaps as many as 12 years....

dnem

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Re: Global sea ice area and extent data
« Reply #487 on: May 04, 2019, 01:46:27 PM »
@  Sark    ...we probably have years of stability yet.......perhaps as many as 12 years....

!2 years? Probably? To totally reconfigure modern industrial society? Oh, phew!! Now I feel so much better. Sorry for the snark, but not very comforting. 

kiwichick16

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Re: Global sea ice area and extent data
« Reply #488 on: May 04, 2019, 05:11:59 PM »
@ dnem....it was meant as an ironic comment......the opposite of comforting

roger white

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Re: Global sea ice area and extent data
« Reply #489 on: May 06, 2019, 08:15:21 AM »
By the latest chart the decade on decade reduction in sea ice extent globally looks like this:
1980's 22,126,425
1990's 22,131,370
2000's 21,872,152
2010's 21,562,353.

So sea ice extent globally went UP in the 1990's?
The decline certainly looks small to the layman...& what would one expect to be " normal" variations from decade anyway...of this magnitude...?


oren

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Re: Global sea ice area and extent data
« Reply #490 on: May 06, 2019, 10:49:11 AM »
The thing is, the Arctic and Antarctic sea ice are very different. The whole global sea ice extent metric does not represent a good physical attribute.
First, the seasonal variability in the Antarctic sea ice is much greater, due to parameters of the Earth's orbit around the sun.
The Antarctic has a continental ice sheet in the middle. The gradual melting of this ice sheet due to global warming is actually expected to increase Antarctic sea ice extent, due to freshening of the top layer of the Southern ocean.
The unexpected bit is what happened since 2016 of a sharply reduced Antarctic sea ice extent.
In addition, Antarctic SIE is at much lower latitudes compared to the Arctic. This also means that Antarctic SIE is "unlimited", as it is not constrained by surrounding landmasses, thus it grows much higher than Arctic SIE and is the principal component in the global SIE.
Bottom line, looking at decadal global SIE trends without diving into the components can be misleading as it lumps different processes together.
« Last Edit: May 06, 2019, 08:09:28 PM by oren »

Pmt111500

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Re: Global sea ice area and extent data
« Reply #491 on: May 06, 2019, 11:44:32 AM »
Ice loss between 1980s - 2010s is somewhat more than area of Spain and a bit less than area of Kenya, humanity has likely done greater amount of deforestation since 1980s. But these areas are by nature, of opposite signs. I've not seen a global graph that would sync the SH and NH areas by the received solar radiation, but this might be an exercise that could be done here. Just flip the SH values around at solstice points so you'll be close. The fact that SH might in fact take in more solar power for the higher ocean area might be ignored.
Amateur observations of Sea Ice since 2003.

Pmt111500

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Re: Global sea ice area and extent data
« Reply #492 on: May 06, 2019, 03:07:13 PM »
Nah, stupid of me to suggest inserting two points of non-congruence to a global year graph, might take some explaining.. Just delay the SH record for six months and sum it up with NH, or the other way around. Other option would be to sum up the anomalies on correct dates, this might show up the potential ENSO effect better than just the northern one (almost no predictability)
Amateur observations of Sea Ice since 2003.

gerontocrat

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Re: Global sea ice area and extent data
« Reply #493 on: May 06, 2019, 03:23:37 PM »
Antarctic Sea Ice Extent reached its maximum value in the satellite record in 2014 at 27 million km2 after increasing very very gradually over the years.There were learned papers published saying this was expected. Why? Vast additional amounts of very cold fresh water entering the Southern Ocean from increased Antarctic Ice Sheet melt (as proved by the GRACE project and field studies), and floating on the ocean surface with the warmer denser salt water underneath. Hence much easier to freeze.

So when in 2016 Antarctic sea ice had crashed to a November maximum of 23.64 million km2 it was a surprise, and many assumed it was a blip. But this is the fourth year of very low sea ice. As yet I have not seen a convincing explanation for this apparent sea-change (duh). I bet AbruptSLR might have a reference or two, and hopefully by the end of summer GRACE-FO will give some new data on AIS mass loss.

Combined with Arctic Sea Ice (not changed that much) this has caused the large change in Global Extent in the last 4 years. See attached graph (if you believe the trendline, problem belong you).
« Last Edit: May 06, 2019, 03:30:56 PM by gerontocrat »
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Tor Bejnar

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Re: Global sea ice area and extent data
« Reply #494 on: May 06, 2019, 03:24:39 PM »
By the way: welcome to the ASIF, Roger.
Arctic ice is healthy for children and other living things.

Tigertown

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Re: Global sea ice area and extent data
« Reply #495 on: May 07, 2019, 05:34:32 PM »
An ol' drunk stumbling off into the night; oh wait, that's the global SIE!

gerontocrat

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Re: Global sea ice area and extent data
« Reply #496 on: May 08, 2019, 01:01:48 PM »
JAXA Global Sea Ice Extent as at 7 May 2019 :-   19,253,124  km2

extent gain has been much above and much below average the last 6 days, but extent has remained lowest, now for the 28th day this year, 22 days in a row, 577 k below 2017.

- extent gain on this day 55k, 20k less than the the average gain of 75 k on this day,
- extent gain from minimum to date is 3.40 million km2, 1.82 million km2 (35%) less than the average gain of 5.23 milllion km2 by this day,
-on average 57.9% of extent gain done and 187 days to maximum, but before that there is a false maximum and minimum before the (usually) true maximum around the 4th of November.

The Perils of Projections
- last 10 years average remaining extent gain would give a maximum of 23.45 million km2,  185k less than the record low maximum in 2016 and lowest in the satellite record.

Being a combination of two separate pieces of data volatility is often very high.
« Last Edit: May 08, 2019, 03:38:12 PM by gerontocrat »
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gerontocrat

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Re: Global sea ice area and extent data
« Reply #497 on: May 11, 2019, 12:16:33 PM »
JAXA Global Sea Ice Extent as at 10 May 2019 :-    19,856,896 km2

Extent gain has been more above than below average the last few days, but extent has remained lowest, now for the 31st day this year, 25 days in a row, 518 k below 2018.

- extent gain on this day 51k, 16k more than the the average gain of 35 k on this day,
- extent gain from minimum to date is 3.61 million km2, 1.74 million km2 (33%) less than the average gain of 5.35 milllion km2 by this day,
-on average 59.3% of extent gain done and 184 days to maximum, but before that there is a false maximum and minimum before the (usually) true maximum around the 4th of November.

The Perils of Projections
- last 10 years average remaining extent gain would give a maximum of 23.53 million km2,  106k less than the record low maximum in 2016 and lowest in the satellite record.

Being a combination of two separate pieces of data volatility is often very high.
"Para a Causa do Povo a Luta Continua!"
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gerontocrat

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Re: Global sea ice area and extent data
« Reply #498 on: May 19, 2019, 11:17:03 AM »
JAXA Global Sea Ice Extent as at 18 May 2019 : 20,380,477 km2

Extent gain has been above and below average the last few days, but extent has remained lowest, now for the 39th day this year, 33 days in a row, 664 k below 2018.

- extent gain on this day 129k, 97k more than the the average gain of 32k on this day,
- extent gain from minimum to date is 4.13 million km2, 1.67 million km2 (29%) less than the average gain of 5.80 milllion km2 by this day,
-on average 64.3% of extent gain done and 170 days to maximum, but before that there is a false maximum and minimum before the (usually) true maximum around the 4th of November.

The Perils of Projections
- last 10 years average remaining extent gain would give a maximum of 23.61 million km2,  a
 mere 31 k less than the record low maximum in 2016 and lowest in the satellite record.

Being a combination of two separate pieces of data volatility is often very high.
"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)

Rich

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Re: Global sea ice area and extent data
« Reply #499 on: May 19, 2019, 12:13:50 PM »
Hooray for some gains. We're now only 1 state of Texas size equivalent short of the previous for this date.