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Metamemesis

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Re: IJIS
« Reply #2500 on: June 05, 2016, 12:49:41 PM »

The open water is counted for area, but not for extent, and so as area drops faster than extent, the compactness percentage goes down.


I believe Neven meant "The open water [within the ice pack] is counted for area extent, but not for extent area, and so as area drops faster than extent, the compactness percentage goes down."

Although I'd go with Neven over my addled mind, unless and until it's amended.


magnamentis

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Re: IJIS
« Reply #2501 on: June 05, 2016, 12:58:18 PM »
just as a reminder to what i posted yesterday, the same day in 2012 had a higher increase still while i concur that we most probably won't see that 2012 drop. I refrained from making a new image, used the one from last page that clearly shows the increase and that we're talking about an increase in 2012 on the very same day.

the rest was said, ice gets spread and hence extent is increasing but not the amount of ice, the opposite is the case when looking at compactness and all the meltwater "burning" through the ice from above LOL



Espen

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Re: IJIS
« Reply #2502 on: June 05, 2016, 01:32:51 PM »
IJIS:

2016 vs 2012
Have a ice day!

jplotinus

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Re: IJIS
« Reply #2503 on: June 05, 2016, 02:12:29 PM »
It might be useful to note that the small increase in SIE recorded 4 June, occurred when the land temperature reading was at or above 0°C at Arctic peripheral locations all around the Arctic.

Tor Bejnar

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Re: IJIS
« Reply #2504 on: June 05, 2016, 04:01:43 PM »
The sentence "The open water is counted for area, but not for extent." has always puzzled me, but is regularly written.  I understand it means something like:
Sea ice area (SIA) is a count of pixels (converted to area units) that the instrument detects as having ice cover.  Open water and melt ponds are 'seen' as being water and so are not counted as having ice coverage.  This is 'obviously' an underestimation when there are lots of melt ponds.  For albedo calculations, this is often a preferred measurement, as melt ponds absorb heat nearly as well as open water.
Sea ice extent (SIE) is a count of grids (converted to area units) with (usually) 15% or more ice pixels detected.  This 'obviously' overestimates 'true' SIA, as most grids that include floe edges get counted as 100% SIE.  However, this tool (SIE) doesn't under estimate grids that include less than 85% melt ponds (which tend to be smaller than a grid square), and during mid- to late- Arctic summer, there can be a lot of melt ponds around.

In other words, "open water is counted for area" means that perceived open water is counted as being water for SIA presentations, and "open water is not counted for extent" means that small bits of open water is not counted as being water for SIE presentations.
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Nick_Naylor

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Re: IJIS
« Reply #2505 on: June 05, 2016, 04:45:39 PM »
The sentence "The open water is counted for area, but not for extent." has always puzzled me, but is regularly written.  I understand it means something like:

In many cases, i believe all that is meant is:
"As melting (or export etc) creates small areas of open water, that open water is not reflected as a reduction of extent until the openings grow a certain amount. On the other hand, they are reflected immediately as a reduction of area."

Metamemesis

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Re: IJIS
« Reply #2506 on: June 05, 2016, 05:17:56 PM »
In short, Neven was right (and I was confused).

"The open water [within the ice pack] is counted [as open water] for area, but not [as open water] for extent, and so as area drops faster than extent, the compactness percentage goes down."

But as most visiters/contributers here know exactly what is meant, we can nicely return this thread back on topic. My bad.


Jim Hunt

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Re: IJIS
« Reply #2507 on: June 05, 2016, 07:05:25 PM »
It might be useful to note that the small increase in SIE recorded 4 June, occurred when the land temperature reading was at or above 0°C at Arctic peripheral locations all around the Arctic.

I did note that! Note also that Wipneus' "high res" AMSR2 extent metric posted a small decrease:

http://GreatWhiteCon.info/2016/06/summer-2016-surface-melt-takes-off/

No such ambiguity on the Pacific periphery however:
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abbottisgone

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Re: IJIS
« Reply #2508 on: June 06, 2016, 05:09:46 AM »
snip Neven
« Last Edit: June 06, 2016, 08:07:51 AM by Neven »
..
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abbottisgone

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Re: IJIS
« Reply #2509 on: June 06, 2016, 05:20:11 AM »
...is this a relatively confirmed observation?

Yes, it means compactness goes down, which means there is open water between floes, or on floes (melt ponds). Compactness is calculated by dividing sea ice area numbers by sea ice extent numbers. The open water is counted for area, but not for extent, and so as area drops faster than extent, the compactness percentage goes down.

This means albedo is lowered, and melting momentum is increased. This momentum can cause a stable decrease during July and August even if weather conditions aren't conducive to melting. 2012 was a prime example of this. You can read the blog posts during the 2012 melting season on the ASIB, if you're interested in the details (for instance, here or here when I started noticing this phenomenon, only realizing later that it had to do with preconditioning during May and June, not with low thickness per se).
Some food for thought, Cheers!

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Espen

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Re: IJIS
« Reply #2510 on: June 06, 2016, 05:22:01 AM »
IJIS:

10,353,315 km2(June 5, 2016)
Have a ice day!

abbottisgone

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Re: IJIS
« Reply #2511 on: June 06, 2016, 05:25:24 AM »
snip Neven
« Last Edit: June 06, 2016, 08:08:21 AM by Neven »
..
But I left school and grew my hair
They didn't understand
They wanted me to be respected as
A doctor or a lawyer man
But I had other plans..........

Espen

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Re: IJIS
« Reply #2512 on: June 07, 2016, 05:22:48 AM »
IJIS:

10,333,107 km2(June 6, 2016)
Have a ice day!

Espen

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Re: IJIS
« Reply #2513 on: June 08, 2016, 05:23:21 AM »
IJIS:

10,297,812 km2(June 7, 2016)
Have a ice day!

Espen

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Re: IJIS
« Reply #2514 on: June 09, 2016, 05:26:49 AM »
IJIS:

10,278,711 km2(June 8, 2016)
Have a ice day!

Espen

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Re: IJIS
« Reply #2515 on: June 10, 2016, 05:22:26 AM »
IJIS:

10,237,369 km2(June 9, 2016)
Have a ice day!

Juan C. García

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Re: IJIS
« Reply #2516 on: June 10, 2016, 05:57:52 AM »
01-jun-16   10,405,086   
02-jun-16   10,374,337   - 30,749
03-jun-16   10,350,720   - 23,617
04-jun-16   10,354,257   +  3,537
05-jun-16   10,353,315   -     942
06-jun-16   10,333,107   - 20,208
07-jun-16   10,297,812   - 35,295
08-jun-16   10,278,711   - 19,101
09-jun-16   10,237,369   - 41,342

Taking speed again?
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.

Jim Pettit

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Re: IJIS
« Reply #2517 on: June 10, 2016, 01:52:57 PM »
01-jun-16   10,405,086   
02-jun-16   10,374,337   - 30,749
03-jun-16   10,350,720   - 23,617
04-jun-16   10,354,257   +  3,537
05-jun-16   10,353,315   -     942
06-jun-16   10,333,107   - 20,208
07-jun-16   10,297,812   - 35,295
08-jun-16   10,278,711   - 19,101
09-jun-16   10,237,369   - 41,342

Taking speed again?
Possibly--though a pretty small dosage. The last five days this year:

-942
-20208
-35295
-19101
-41342
--------
-116888

The same days in 2012:
-85613
-95330
-144639
-182382
-152587
---------
-660551

2016's lead over 2012 is now 455k . A week ago it was more than a million...

magnamentis

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Re: IJIS
« Reply #2518 on: June 10, 2016, 02:27:56 PM »
2016's lead over 2012 is now 455k . A week ago it was more than a million...

sure, there is no linearity, wait for that stall that happend in 2012 a few days ahead from now, could well be that at that exact time the 30% ice (not literally) extent will drop below 15 and one would be back to around a million within 2-3 days.

however as it was discussed in another thread, i don't believe in a record low this year, but tend not to think too much short term. short term reaction based on short term events is what politicians and often company leaders do with next elections or next quarterly reports in mind which is one big factor why we have GW at all and why it's so difficult to fight it.

i for my part sit tight and watch, the energy is in the water and in the air (in the system ) and it will eventually prevail over local and weather events.
« Last Edit: June 11, 2016, 12:17:46 PM by magnamentis »

kingbum

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Re: IJIS
« Reply #2519 on: June 10, 2016, 09:29:49 PM »
I believe what you will find is that the low extent over the previous freezing season was due in part to the massive furnace that is known as El Niño. The Pacific waters right now are in a neutral phase and heading towards La Niña conditions for Autumn and Winter. So what does this mean for the Arctic? I don't see conditions late in the season being conducive to 2016 beating out on 2012 I think the summer season will be a slow melt out. I also believe that if the current La Niña forecast pans out that there will be a really good refreeze as there typically is during La Niña events in short another recovery period like 2013/2014 is in the cards for 2017/2018

Ice Shieldz

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Re: IJIS
« Reply #2520 on: June 10, 2016, 11:30:17 PM »
I also believe that if the current La Niña forecast pans out that there will be a really good refreeze as there typically is during La Niña events in short another recovery period like 2013/2014 is in the cards for 2017/2018

Hmm could be.  I'm inclined to think that our super El Nino's atmospheric lag-time, along with a potentially weak nina and abnormally hot oceans in non-enso regions, will lead to poor refreeze conditions. 

There's also the big X factor of how the jet stream will respond to the current melt – specifically what effect will a 2012 or less extent have on the jet stream when coupled with already warmer arctic region oceans.

DavidR

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Re: IJIS
« Reply #2521 on: June 11, 2016, 04:32:40 AM »

2016's lead over 2012 is now 455k . A week ago it was more than a million...
2012 has four more succesive century drops,  and then only three more for the rest of  the month.  2016 has to drop 150K in four days to avoid getting caught. After that the 2012 June drop is just average, so 2016 doesn't have to do that much  to stay ahead for the rest  of the month.  In fact the 2012 extent  is still virtually the same amount  below average on July 22nd as it was on  June 13th.

The NSIDC Area/Extent ratio is the lowest for 9th of June, just  lower than 2012 and 2007. This is the first time it has been below 2012 in a month. 
« Last Edit: June 11, 2016, 08:42:56 AM by DavidR »
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DavidR

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Re: IJIS
« Reply #2522 on: June 11, 2016, 08:35:33 AM »
It  looks like the IJIS website is down again. At this rate we may never know if 2016 sets a new record.
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Dorsetmetman

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Re: IJIS
« Reply #2523 on: June 11, 2016, 09:55:48 AM »
Seems to be working for me ok now.

10,190,381km^2, so down 46,988km^2 on yesterday.


BornFromTheVoid

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Re: IJIS
« Reply #2524 on: June 11, 2016, 10:23:31 AM »
If we continue losing extent at the average rate of the last 10 days (23.67k/day), we'll no longer be lowest on record  in 6 days, and we'll be above 2012 in 8.
I recently joined the twitter thing, where I post more analysis, pics and animations: @Icy_Samuel

Espen

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Re: IJIS
« Reply #2525 on: June 11, 2016, 12:47:35 PM »
IJIS:

10,190,381 km2(June 10, 2016)
Have a ice day!

Paddy

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Re: IJIS
« Reply #2526 on: June 11, 2016, 02:16:36 PM »
If we continue losing extent at the average rate of the last 10 days (23.67k/day), we'll no longer be lowest on record  in 6 days, and we'll be above 2012 in 8.

That's a pretty big "If" though. See, for instance, how much extent decline has been at odds with the faster rate of area decline, which suggests some mixture of melt ponding and/or ice spreading out. Both of which would lead to greater melting ahead.

oren

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Re: IJIS
« Reply #2527 on: June 11, 2016, 02:21:20 PM »
Eyeballing the chart, I believe 2016 will miss hitting the 2012 corner and will keep its lowest on record status for quite a while. My predictions have a bad track record for now, but I'll keep posting them and one day I'll be right...

magnamentis

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Re: IJIS
« Reply #2528 on: June 11, 2016, 02:30:37 PM »
Eyeballing the chart, I believe 2016 will miss hitting the 2012 corner and will keep its lowest on record status for quite a while. My predictions have a bad track record for now, but I'll keep posting them and one day I'll be right...

and it will be this time, posted the same in other words in the melting season thread last night, this time you're spot on :-)  ;)

BornFromTheVoid

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Re: IJIS
« Reply #2529 on: June 11, 2016, 02:42:25 PM »
That's a pretty big "If" though. See, for instance, how much extent decline has been at odds with the faster rate of area decline, which suggests some mixture of melt ponding and/or ice spreading out. Both of which would lead to greater melting ahead.

True, but I doubt many people expected this very slow extent decline to last a third of the month either. Whatever happens, our massive lead over the other low years will be large gone.

I recently joined the twitter thing, where I post more analysis, pics and animations: @Icy_Samuel

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Re: IJIS
« Reply #2530 on: June 11, 2016, 04:22:03 PM »
Hi BFTV!

I certainly did not expect things to slow so much? That said I have to wonder if our being so far 'ahead' of other years is meaning we are a little out of phase with other melt seasons and part of the reason for the slowing was a pre-conditioning of the pack that never had a chance to occur before?

Eventually, over time, we will see melt out become progressively early as ice type/thickness respond to warming meaning more open water ever earlier in melt season. This year we saw large areas of open water that we do not normally see.

 Whilst we watched ice melt surge ahead of other years the open waters continued to soak up heat that , in past years, would not normally have happened.

I cannot believe that this will count for nothing but that it is a glimpse into the future behaviours of melt seasons?
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Espen

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Re: IJIS
« Reply #2531 on: June 12, 2016, 10:07:58 AM »
IJIS:

10,154,944 km2(June 11, 2016)
Have a ice day!

Espen

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Re: IJIS
« Reply #2532 on: June 13, 2016, 05:22:18 AM »
IJIS:

10,130,495 km2(June 12, 2016)
Have a ice day!

Espen

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Re: IJIS
« Reply #2533 on: June 14, 2016, 05:21:47 AM »
IJIS:

10,100,637 km2(June 13, 2016)
Have a ice day!

Jim Pettit

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Re: IJIS
« Reply #2534 on: June 14, 2016, 01:08:13 PM »
June-to-date IJIS extent loss has been by a wide margin the lowest in the past decade. In fact, the 2006-2015 average month-to-date loss has been 703k, more than double this year's sluggish 326k. Most notably, perhaps, is the very obvious downward trendline in early June SIE decreases:



At this rate, early June will be a time of extent increase by 2019 or so.  ;)

Neven

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Re: IJIS
« Reply #2535 on: June 14, 2016, 01:23:03 PM »
Amazing. One would think some negative feedback is kicking in, or some external factor that has come into play (Pacific SST or SLP or some such).
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Re: IJIS
« Reply #2536 on: June 14, 2016, 01:28:12 PM »

At this rate, early June will be a time of extent increase by 2019 or so.  ;)

Only at the cost of reduced volume/concentration though?
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abbottisgone

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Re: IJIS
« Reply #2537 on: June 15, 2016, 03:27:27 AM »
June-to-date IJIS extent loss has been by a wide margin the lowest in the past decade. In fact, the 2006-2015 average month-to-date loss has been 703k, more than double this year's sluggish 326k. Most notably, perhaps, is the very obvious downward trendline in early June SIE decreases:



At this rate, early June will be a time of extent increase by 2019 or so.  ;)

Yeh, worthy of note alright!

Identification of trend can't be a bad thing as to solve a problem one must first sufficiently define it... for what else is method I ask you?

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Re: IJIS
« Reply #2538 on: June 15, 2016, 05:23:07 AM »
IJIS:

10,054,193 km2(June 14, 2016)
Have a ice day!

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Re: IJIS
« Reply #2539 on: June 15, 2016, 06:57:44 AM »
And there is no clear-cut correlation with ENSO ...
If this year does not go below 2012, otherwise scientists will have to find a clear-cut correlation
The 2014-2016 El Nino should generate a new record unless it holds on to neutral for another year. It might do so considering the amount of heat in the pacific.
Dispite living in an Arctic nation, I don't follow the ice as close as others in here. But instead of looking too much at the past to find correlations, I believe nailing those global circulation patterns is the key to future forecasts. First pic is the obvious one, second is CDAS Nino4 anomalies for yesterday by Levi Cowan, third is from a recent study trying to identify an equator-Arctic teleconnection from an area slightly larger than the Nino4, fourth is an example of what I would like to see more of by science. A Markov regime-switching framework, in this case to forecast the SOI. That might not be successful, but I will definately folllow it. If reality should follow, the next winter in the Arctic might be even more interesting.

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Re: IJIS
« Reply #2540 on: June 15, 2016, 08:45:32 AM »

sorry if i disagree, what caught my eyes in your post was the word "rapidly" which i know by heart is not true

Happy with rapidly yet?  ;)

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Re: IJIS
« Reply #2541 on: June 15, 2016, 09:25:19 AM »
The 46k drop yesterday is out second biggest drop of the month, yet is still way below the average for the 14th of 64k. Not one single daily drop this month has even matched the 2003-2015 average.
I recently joined the twitter thing, where I post more analysis, pics and animations: @Icy_Samuel

magnamentis

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Re: IJIS
« Reply #2542 on: June 15, 2016, 10:38:22 AM »

sorry if i disagree, what caught my eyes in your post was the word "rapidly" which i know by heart is not true

Happy with rapidly yet?  ;)

if you read that post carefully you see that i was talking about THAT day and even mentioned that it might change withing a few days, so this rebuke is an unnecessary, ego-based and then way too late  because we are now about 10 days from that, way beyond anything that was discussed then and funnily we're still not there, hence rapidly would no make about 10 days without hitting the mark. that day when you said rapidly the gap got even bigger for the last time, that was all i said. please refrain from such self-profiling posts, the are disturbing.

southseas

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Re: IJIS
« Reply #2543 on: June 15, 2016, 10:45:27 AM »
Goodness, I'm glad I included the wink emoticon.

Imagine your response if you didn't know I was making a gentle joke.

Never mind.

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Re: IJIS
« Reply #2544 on: June 15, 2016, 11:45:56 AM »
The 46k drop yesterday is out second biggest drop of the month, yet is still way below the average for the 14th of 64k. Not one single daily drop this month has even matched the 2003-2015 average.
Wipneus reported a 91.3k extent drop on AMSR2 yesterday.
Maybe IJIS is averaging ?
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Re: IJIS
« Reply #2545 on: June 15, 2016, 12:28:13 PM »
Wipneus uses higher-resolution data. If (say) there are four pixels next to each other, and one of them drops below 15% concentration, Wipneus will calculate that as a loss of area.  IJIS will average across all four pixels (since their resolution is coarser) and it will not show up as an extent drop.

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Re: IJIS
« Reply #2546 on: June 15, 2016, 01:23:18 PM »
The 46k drop yesterday is out second biggest drop of the month, yet is still way below the average for the 14th of 64k. Not one single daily drop this month has even matched the 2003-2015 average.
Wipneus reported a 91.3k extent drop on AMSR2 yesterday.
Maybe IJIS is averaging ?

Yes, 2 day average.

There are other reasons why the numbers differ, some due to the method (resolution, algorithm) some can be regarded just as "noise".

Espen

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Re: IJIS
« Reply #2547 on: June 16, 2016, 05:28:45 AM »
IJIS:

9,993,628 km2(June 15, 2016)
Have a ice day!

bbr2314

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Re: IJIS
« Reply #2548 on: June 16, 2016, 05:45:44 AM »
For all the talk about how the melt season has slowed to most pathetic ever & is destined to peter out as the ice remains completely intact, it sure seems odd that 2016 has taken the record for earliest to cross below 10M KM2.

Juan C. García

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Re: IJIS
« Reply #2549 on: June 16, 2016, 06:23:36 AM »
For all the talk about how the melt season has slowed to most pathetic ever & is destined to peter out as the ice remains completely intact, it sure seems odd that 2016 has taken the record for earliest to cross below 10M KM2.

That's right! 2012 starts to be slower at the second half of June. Even that 2016 is slow now, it could keep the lead for a while.
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.