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Neven

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Re: IJIS
« Reply #4600 on: July 17, 2017, 09:52:54 AM »
... what?  This forum's OK with casual racism now?

I don't know if it's racism, but it's certainly a failed attempt at humour.

In the meantime we await that triple century break.  ;)

Edit: Upon further reflection, after reading the complaints people sent me, I've decided to redact the offensive part of Hyperion's post.
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Cato

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Re: IJIS
« Reply #4601 on: July 17, 2017, 11:55:26 AM »
As I expected, the trend is now showing early signs of a slower decrease rate. The synoptic configuration for the next 7-10 days is definitely not bad for the ice. Yet, if confirmed by the next few runs, it would lead in my opinion to a further flattening of the curve. The maps are quite interesting indeed: persistence of LP systems in the absence of too big gradients. In other terms, conditions conductive to ice scattering and preservation due to cloudy skies, some precipitations and no inflow of warm winds from lower latitudes.

This is even more relevant in consideration of the fact that this is a key moment of the melting season and "fresh" conditions now would probably determine the outcome of the whole melting season.

gerontocrat

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Re: IJIS
« Reply #4602 on: July 17, 2017, 02:19:20 PM »
As I expected, the trend is now showing early signs of a slower decrease rate. The synoptic configuration for the next 7-10 days is definitely not bad for the ice. Yet, if confirmed by the next few runs, it would lead in my opinion to a further flattening of the curve. The maps are quite interesting indeed: persistence of LP systems in the absence of too big gradients. In other terms, conditions conductive to ice scattering and preservation due to cloudy skies, some precipitations and no inflow of warm winds from lower latitudes.

This is even more relevant in consideration of the fact that this is a key moment of the melting season and "fresh" conditions now would probably determine the outcome of the whole melting season.
The chaps on the 2017 melting season thread have a totally contrary view on the way things are going. I also have looked at various weather sites and have seen nothing to tell me that climatic conditions are going to change soon to promote increased melting. This is such a contrast to last winter / spring with the jet stream dragging vast plumes of warm air into the high arctic and then sending vast plumes of freezing air down south.
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Shared Humanity

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Re: IJIS
« Reply #4603 on: July 17, 2017, 05:19:38 PM »
... what?  This forum's OK with casual racism now?

I don't know if it's racism, but it's certainly a failed attempt at humour.

In the meantime we await that triple century break.  ;)

Edit: Upon further reflection, after reading the complaints people sent me, I've decided to redact the offensive part of Hyperion's post.

Given the current political and social climate in the U.S., I have zero tolerance for these kinds of comments even if only failed attempts at humor.

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Re: IJIS
« Reply #4604 on: July 17, 2017, 05:32:36 PM »
As I expected, the trend is now showing early signs of a slower decrease rate. The synoptic configuration for the next 7-10 days is definitely not bad for the ice. Yet, if confirmed by the next few runs, it would lead in my opinion to a further flattening of the curve. The maps are quite interesting indeed: persistence of LP systems in the absence of too big gradients. In other terms, conditions conductive to ice scattering and preservation due to cloudy skies, some precipitations and no inflow of warm winds from lower latitudes....
...
The chaps on the 2017 melting season thread have a totally contrary view on the way things are going. I also have looked at various weather sites and have seen nothing to tell me that climatic conditions are going to change soon to promote increased melting.
I agree here

Cato

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Re: IJIS
« Reply #4605 on: July 17, 2017, 05:49:13 PM »
As I expected, the trend is now showing early signs of a slower decrease rate. The synoptic configuration for the next 7-10 days is definitely not bad for the ice. Yet, if confirmed by the next few runs, it would lead in my opinion to a further flattening of the curve. The maps are quite interesting indeed: persistence of LP systems in the absence of too big gradients. In other terms, conditions conductive to ice scattering and preservation due to cloudy skies, some precipitations and no inflow of warm winds from lower latitudes....
...
The chaps on the 2017 melting season thread have a totally contrary view on the way things are going. I also have looked at various weather sites and have seen nothing to tell me that climatic conditions are going to change soon to promote increased melting.
I agree here


Guys, I'm not an expert in sea-ice, and therefore I'm very reluctant to make my point in front of so many experts in the field, writing on this great forum. If the chaps you are making reference to are basing their analysis on the conditions of the ice, well, I don't have the basic knowledge to oppose their view.

But if their analyses are based on synoptic configuration only, well, I can very well reinstate my point and confirm that weather conditions (based on the current model runs) are not conductive to melting. Or better, to bigger-than-average melting. Those maps are very clear to me. It is difficult to get better conditions for ice preservation than the ones depicted in the latest runs.

Even the temperature forecasts at sea level (though quite variable from run to run and not so reliable in general) show a clear temperature decrease over rather vast areas in the next few days. And it's not so normal (especially in this extremely warm period we're living in) to see below-zero temperatures over rather vast areas as you can see from the latest model runs.

And then, as usual... only time will tell.


oren

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Re: IJIS
« Reply #4606 on: July 17, 2017, 05:53:39 PM »
There is the issue of ice thickness, postulated by PIOMAS to be lower this year. If this is correct, an average melt could see above-average area/extent disappearance. Time will tell.

Tor Bejnar

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Re: IJIS
« Reply #4607 on: July 17, 2017, 06:13:35 PM »
It appears that everybody agrees that "Time" isn't very good at keeping secrets long-term   ;D
Arctic ice is healthy for children and other living things.

magnamentis

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Re: IJIS
« Reply #4608 on: July 17, 2017, 06:23:16 PM »
@Shared Humanity

while are d'accord that racism is evil, IMMEDIATE public uproars of the kind seen here are not target leading and almost every war in  human history was based at least in parts of this kind of "phariseeism" ( i know that word will cause reactions but this is what it is IMO.

it's good to be agains racism but it's not necessary to lynch someone on a first "fauxpas" which as well could have been a lapsus or language barrier and could have been handled with a friendly hint and/or asking how it was meant before shooting broadsides at someone who generally posted quite useful stuff. this harsh reactions are not fair without checking on intention and first hint friendly and are as intolerant as racism itself.

aggression has never ever lead to anything good, at least not ultimately, short term satisfaction of feeling just is not the goal but making people understand is. obeying is not based on conviction and therefore won't last.
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CognitiveBias

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Re: IJIS
« Reply #4609 on: July 17, 2017, 06:33:37 PM »
@Shared Humanity

while are d'accord that racism is evil, IMMEDIATE public uproars of the kind seen here are not target leading and almost every war in  human history was based at least in parts of this kind of "phariseeism" ( i know that word will cause reactions but this is what it is IMO.

it's good to be agains racism but it's not necessary to lynch someone on a first "fauxpas" which as well could have been a lapsus or language barrier and could have been handled with a friendly hint and/or asking how it was meant before shooting broadsides at someone who generally posted quite useful stuff. this harsh reactions are not fair without checking on intention and first hint friendly and are as intolerant as racism itself.

aggression has never ever lead to anything good, at least not ultimately, short term satisfaction of feeling just is not the goal but making people understand is. obeying is not based on conviction and therefore won't last.

+1

budmantis

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Re: IJIS
« Reply #4610 on: July 17, 2017, 07:02:14 PM »
Excellent point Magnamentis.

BudM

Ice Shieldz

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Re: IJIS
« Reply #4611 on: July 17, 2017, 07:25:16 PM »
I know we should get back on topic, but i was quite moved by Magna's words especially given all the discord and righteousness that's being stirred up by both conservatives and liberals. I feel we really need to promote greater empathy to make the changes necessary - and not just for other humans but for the planet in general.

Ned W

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Re: IJIS
« Reply #4612 on: July 17, 2017, 07:28:45 PM »
IJIS:

7,590,232 km2(July 16, 2017)down 83,771  km2 and 4th lowest measured for the date.
Starting from June 10th, the predict-o-matic predicted that on July 16th there would have been a reduction in extent of 2.985 million km2.  Actual reduction: 2.972 million km2. 

Accuracy of the predict-o-matic: better than 99.5%.  Not bad!

Of course, the prediction was +/- 0.802 million km2.  So the high level of accuracy is mostly luck.

As a reminder, its prediction for the eventual September daily minimum is 4.213 million km2 extent. If that's also accurate to within 99.5% I will be very surprised.


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Re: IJIS
« Reply #4613 on: July 17, 2017, 07:55:39 PM »
Move along, please, folks. This isn't the place. Neven dealt with the situation as he saw fit, so any further meta discussions about a particular comment and the reaction to it need to be posted in the "The Forum" section, if they need to be posted at all.

Thanks for your cooperation.

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Re: IJIS
« Reply #4614 on: July 18, 2017, 06:09:56 AM »
IJIS:

7,479,327 km2(July 17, 2017)down 110,905 km2 and 4th lowest measured for the date.
Have a ice day!

mmghosh

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Re: IJIS
« Reply #4615 on: July 18, 2017, 06:19:58 AM »
Setting up nicely for August cyclones...

Tigertown

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Re: IJIS
« Reply #4616 on: July 18, 2017, 06:26:58 AM »
Yogi Berra comes to mind about now.

Neven

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Re: IJIS
« Reply #4617 on: July 18, 2017, 08:35:11 AM »
I wonder if we'll see another century break tomorrow and the day after, given the 'stall' in the Uni Hamburg AMSR2 and NSIDC data as reported by Wipneus. JAXA is less jittery, but if there are no big drops reported elsewhere today, the series may come to an early end (never mind the fact that yesterday didn't see a century break, still 6 out of 7).
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Tigertown

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Re: IJIS
« Reply #4618 on: July 18, 2017, 08:57:20 AM »
A stall in extent loss would not be a big surprise, as we seem to be loosing a lot of ice from the middle of the pack now.

jplotinus

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Re: IJIS
« Reply #4619 on: July 18, 2017, 01:26:43 PM »
Stall? Worldview reveals few, if any, impediments to an open Northern route as of 18th July.

Ned W

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Re: IJIS
« Reply #4620 on: July 18, 2017, 01:39:34 PM »
Better and better ...

Actual decrease in extent, 10 June-17 July:  3.023 million km2
Predicted decrease in ext, 10 June-17 July:  3.025 million km2

Accuracy: 99.93%

 :)

Paddy

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Re: IJIS
« Reply #4621 on: July 18, 2017, 01:44:25 PM »
Yogi Berra comes to mind about now.

Indeed, tis folly to prophecy. But it's also fun to try :-).

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Re: IJIS
« Reply #4622 on: July 18, 2017, 03:13:36 PM »
Terry, you keep using this term. I know you are punning "Amen," but this word has a kind of interesting etymology. It is written with katakana, basically like italics in English, it is use for words that are not originally Japanese.

This fact got me interested, so I dug a bit and found that 'ramen' is what the Japanese did to the Chinese word that we (those who frequent Chinese restaurants, at least) know as Lo Mein...basically a noodle dish.

Just thought you might find it interest. Sorry for the OT.


Thanks so much for the unsolicited lesson in the secular etymology of a holy word held sacred by the PP's of FSM!  >:(


As a Practicing Pastafarian in the church of the FSM I much prefer Ramen to "the word that shall go unspoken".


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May a Thousand Demented Harpists with Hang Nails Claw Relentlessly at the Scrotum of your Enemies


Ramen, Matey  8)

gregcharles

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Re: IJIS
« Reply #4623 on: July 18, 2017, 07:40:56 PM »
Hey, today could finally be the day that 2017 passes 2016 for the first time since mid-April! Also, current extent is now lower than the minimum extent for 1980, and will probably pass most of the rest of the 1980s' miniimums over the course of the next week.

Neven

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Re: IJIS
« Reply #4624 on: July 18, 2017, 08:11:59 PM »
I wonder if we'll see another century break tomorrow and the day after, given the 'stall' in the Uni Hamburg AMSR2 and NSIDC data as reported by Wipneus. JAXA is less jittery, but if there are no big drops reported elsewhere today, the series may come to an early end (never mind the fact that yesterday didn't see a century break, still 6 out of 7).

No big drops reported elsewhere, so JAXA will probably follow suit.
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Espen

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Re: IJIS
« Reply #4625 on: July 19, 2017, 07:47:12 AM »
IJIS:

7,377,477 km2(July 18, 2017)down 101,850 km2 and 3rd lowest measured for the date.
Have a ice day!

Ned W

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Re: IJIS
« Reply #4626 on: July 19, 2017, 01:12:11 PM »
Another century break! 

If I'm counting right, 2007, 2011, and 2013 each had century breaks in 6 of the next 7 days.  Wow. At the other extreme, 2010 had none, and 2008/2009/2014 only had 1 each.  Average daily losses range from 121K/day (2011) to 53K/day (2010).
So it was century breaks on 5 of the 7 days after I posted that -- and on 7 of the past 8 days. Impressive. 

Average daily losses were 108K during the week I highlighted (4th place) and 127K over the past 8 days (3rd place, barely lower than 2015).



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Re: IJIS
« Reply #4627 on: July 19, 2017, 03:04:15 PM »
Despite the admittedly impressive 7 century+ breaks in the last 8 days, extent loss from maximum extent to July 18 is still 4 percent LESS than the average for the last 10 years. Also by this time, on average just over two-thirds of total extent loss (max to min) has occurred. If and only if this above average melt rate continues for a while longer, 2nd lowest extent is possible.
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Quantum

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Re: IJIS
« Reply #4628 on: July 19, 2017, 04:19:13 PM »
That surely has to be the last century break in this run.

Tigertown

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Re: IJIS
« Reply #4629 on: July 19, 2017, 04:42:11 PM »
A major compaction event would be needed right now to slow down the melt, as there is just too much easy pickings around the perimeter. Of course, the same compaction would drop extent numbers immediately.

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Re: IJIS
« Reply #4630 on: July 20, 2017, 09:47:01 AM »
IJIS:

7,290,578 km2(July 19, 2017)down 86,899 km2 and 3rd lowest measured for the date.
Have a ice day!

bbr2314

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Re: IJIS
« Reply #4631 on: July 21, 2017, 05:28:15 AM »
IJIS:

7,290,578 km2(July 19, 2017)down 86,899 km2 and 3rd lowest measured for the date.
7/20

7.194, -96K.

If this keeps up 2017 takes lead tomorrow or next day and then begins putting distance with 2012, which is still at 6.03M as of 8/2.

That means 2017 has 13 days to melt 1.164 million KM2 of ice in order to be ahead of 2012 by the end of its relative plateau, requiring an average melt of 89K KM2 or greater per day.

Given we are coming off over a week of century breaks and almost matched that today, 2017 seems poised to put over 100K KM2 of distance between it and 2012 come 8/2 (IMO).

If 2017 keeps up its numeric rate of melt for the last 7 days, it will be at just over 5.8M KM2 come 8/2, for what it's worth (or over 200K below 2012).

Tigertown

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Re: IJIS
« Reply #4632 on: July 21, 2017, 05:42:36 AM »
 Ice that I think will be gone by August.
All of that in Baffin, that in the CAA by melt & export in tandem. The current Fram export. Note there may be new ice moved from the north down to any of these areas by then, but I mean what is there now. Also, Kara and what is behind the N. S. Islands. Laptev. Some areas in the pack that are starting to smart a little. Can anyone guestimate the SIE loss on these?

I know somebody can add to that list.

Neven

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Re: IJIS
« Reply #4633 on: July 21, 2017, 06:50:55 AM »
7/20

7.194, -96K.

If this keeps up 2017 takes lead tomorrow or next day and then begins putting distance with 2012, which is still at 6.03M as of 8/2.

That means 2017 has 13 days to melt 1.164 million KM2 of ice in order to be ahead of 2012 by the end of its relative plateau, requiring an average melt of 89K KM2 or greater per day.

Given we are coming off over a week of century breaks and almost matched that today, 2017 seems poised to put over 100K KM2 of distance between it and 2012 come 8/2 (IMO).

If 2017 keeps up its numeric rate of melt for the last 7 days, it will be at just over 5.8M KM2 come 8/2, for what it's worth (or over 200K below 2012).

2012 had some huge drops in the coming week (including a double century break mentioned earlier), but then a handful of slow days, before seriously dropping off during GAC-2012. But given that there is still some 'piggy bank' ice, like TT says, and the decrease has picked up again in other datasets, 2017 might indeed be able to keep pace with 2012 until the end of the month, and then with 2007 during August. There might be another couple of century breaks in the works in the next 10 days.

Which would be quite amazing, given that the weather hasn't been anything like 2012, let alone 2007. Evidence, of course, that PIOMAS has it right with regards to ice being thin.
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bbr2314

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Re: IJIS
« Reply #4634 on: July 21, 2017, 08:08:32 AM »
7/20

7.194, -96K.

If this keeps up 2017 takes lead tomorrow or next day and then begins putting distance with 2012, which is still at 6.03M as of 8/2.

That means 2017 has 13 days to melt 1.164 million KM2 of ice in order to be ahead of 2012 by the end of its relative plateau, requiring an average melt of 89K KM2 or greater per day.

Given we are coming off over a week of century breaks and almost matched that today, 2017 seems poised to put over 100K KM2 of distance between it and 2012 come 8/2 (IMO).

If 2017 keeps up its numeric rate of melt for the last 7 days, it will be at just over 5.8M KM2 come 8/2, for what it's worth (or over 200K below 2012).


2012 had some huge drops in the coming week (including a double century break mentioned earlier), but then a handful of slow days, before seriously dropping off during GAC-2012. But given that there is still some 'piggy bank' ice, like TT says, and the decrease has picked up again in other datasets, 2017 might indeed be able to keep pace with 2012 until the end of the month, and then with 2007 during August. There might be another couple of century breaks in the works in the next 10 days.

Which would be quite amazing, given that the weather hasn't been anything like 2012, let alone 2007. Evidence, of course, that PIOMAS has it right with regards to ice being thin.

I wonder whether this impending setup will negate the need for an exact equivalent of a GAC.

Models are now showing a massive typhoon developing and persisting in the eastern West Pacific for at least the next ten days. It flings up several different spigots of moisture but the largest arrives in the Arctic by D7 and is visible surrounding the 981mb low in the frame below.

Such an event will be accompanied by substantial liquid precipitation and heat, and the ramifications are likely to be quite severe (IMO).


Espen

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Re: IJIS
« Reply #4635 on: July 21, 2017, 09:47:31 AM »
IJIS:

7,194,069 km2(July 20, 2017)down 96,509 km2 and 3rd lowest measured for the date.
Have a ice day!

Cato

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Re: IJIS
« Reply #4636 on: July 21, 2017, 10:59:34 AM »
Fully agree with Neven's point about the impressive extent decrease in spite of cooler-than-usual conditions over the Arctic for quite a few weeks so far.

I guess the next 10 days will decide most of the final outcome in terms of minimum extent: conditions will be cool, cooler than today, with significant areas of the Arctic below 0C and associated snowfalls. No significant inflow of warm air is forecast, just some quick "injections" of warmer and wetter air from Pacific due to the H+ block forcing LPs to enter the Arctic, a typical late-summer synoptic pattern.

Regarding precipitations I'm attaching the maps of accumulated snowfalls over the next 6 days (ECMWF). Wait and see, it's an exciting end of melting season indeed.

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Re: IJIS
« Reply #4637 on: July 21, 2017, 02:21:33 PM »
Just to say that on July 20th extent became lower than the 1980's average minimum, and will likely stay that way for at least three months. That is quite a lot of open water collecting a lot of kinetic energy for quite a long time.
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Re: IJIS
« Reply #4638 on: July 21, 2017, 06:43:57 PM »
I'm aware of expressions of 'surprise' that Jaxa extent declines have been able to stay at or near the century drop level during peak melt period. Mainly, weather factors in the CAB, where most of the sea ice is to be found, and also areas like Beaufort that have not melted out as much as was the case in 2016 at this time, are relied on to suggest smaller declines are coming.

As I see it, the weather in the CAB is not cold enough to cause extent increases during late July on one hand, but vulnerable ice in Baffin looks poised to go poof literally on a daily basis now, on the other.

Wip's Baffin extent chart shows a 300k piggy bank extending north and south of Clyde River. It does not appear that it is unseasonably cold in Clyde River, where temps near 10° are likely to occur on a consistent basis in coming days. I expect Baffin extent losses to contribute to more century drops.

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Re: IJIS
« Reply #4639 on: July 22, 2017, 09:15:26 AM »
IJIS:

7,100,408 km2(July 21, 2017)down 93,661 km2 and 2nd lowest measured for the date.
Have a ice day!

gerontocrat

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Re: IJIS
« Reply #4640 on: July 22, 2017, 03:25:09 PM »
I was weeding me environment directory and found a little file dated 8th June on prospects for various outcomes as regards sea ice extent. Below is the table for 21st July. There is not a lot of difference. Mind you, I still think that 2nd lowest is most likely - low volume and warm seas. Also added a graph.
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magnamentis

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Re: IJIS
« Reply #4641 on: July 22, 2017, 07:54:01 PM »
I was weeding me environment directory and found a little file dated 8th June on prospects for various outcomes as regards sea ice extent. Below is the table for 21st July. There is not a lot of difference. Mind you, I still think that 2nd lowest is most likely - low volume and warm seas. Also added a graph.

sounds reasonable. i think that most users for the last 3-4 months believe that second lowest is the most probable should nothing extraordinary happen while a better (more ice remaining) or worse result are still possible even though not by a big margin.

extraordinary could be another GAC or a series of rather strong cyclones. another extraordinary event could happen due to much more thin ice than any other year in the past.

the only thing that is catching my eyes almost every day is that most people who refer to 2012 and the GAC somehow seem to deny the possibility that such a GAC can happen again, while i believe that the next of those is imminent and chances are increasing each year.

my point is that we should at least keep that possibility as one of the more probable scenarios and therefore calculate (make forecasts) that include the current almost linear development as well as a new GAC and/or sudden death due to thinness and fragmentation.

one possibility can be added which is the combination of the two. that could bring us very close to what common sense right now sees as almost impossible and of course there is no way to predict any of that.
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oren

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Re: IJIS
« Reply #4642 on: July 23, 2017, 12:44:17 AM »
I was weeding me environment directory and found a little file dated 8th June on prospects for various outcomes as regards sea ice extent. Below is the table for 21st July. There is not a lot of difference. Mind you, I still think that 2nd lowest is most likely - low volume and warm seas. Also added a graph.
I finally realised what was bothering me with your cery reasonable predictions, and it's not even PIOMAS-related. As 2012 is more or less at the same extent currently, and has been so for a while, that means that 2012 gave almost the same surprise that is now forecast as having a very low probabilty. But one out of ten years is 10%, not really negligible. To counter this, I would suggest adding somewhere in the table the % of average melt actually achieved by 2012 (and 2016, 2007) from now until minimum. This will enable to gause a range of possible outcomes based on actual past events.

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Re: IJIS
« Reply #4643 on: July 23, 2017, 07:51:10 AM »
IJIS:

7,059,031 km2(July 22, 2017)down 41,377 km2 and 4th lowest measured for the date.
Have a ice day!

Quantum

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Re: IJIS
« Reply #4644 on: July 23, 2017, 03:41:39 PM »
Finally. I must admit, despite JAXA not being that useful a metric for sea ice health, I found this run of centuries quite emotionally taxing! Despite the inevitable collapse of the arctic sea ice, I always come to this thread with foolish levels of optimism.

gerontocrat

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Re: IJIS
« Reply #4645 on: July 23, 2017, 04:13:37 PM »

As 2012 is more or less at the same extent currently, and has been so for a while, that means that 2012 gave almost the same surprise that is now forecast as having a very low probabilty. But one out of ten years is 10%, not really negligible. To counter this, I would suggest adding somewhere in the table the % of average melt actually achieved by 2012 (and 2016, 2007) from now until minimum. This will enable to gause a range of possible outcomes based on actual past events.
I believe that the late melt in 2012, some 30 percent or nearly 1 million km2 above the average, is unique in the satellite record, but I may be wrong. A one in ten event it certainly was not. Herewith a table.
ps: Not predictions, attempts to show what is required for an event and the likelihood thereof (from historical records).

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Cid_Yama

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Re: IJIS
« Reply #4646 on: July 23, 2017, 05:43:36 PM »
The mistake you and others make is the assumption that this year's ice is anything like previous years.  Or that this year's climate is anything like previous years.   Or that atmospheric circulation or ocean currents and temperatures are anything like previous years.

You can crunch numbers all you want, but if circumstances in the past in no way resemble current circumstances, then it's just GIGO.

You can't treat a transforming system as if it's a static one and derive anything useful.

 

« Last Edit: July 23, 2017, 05:49:13 PM by Cid_Yama »

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Re: IJIS
« Reply #4647 on: July 23, 2017, 06:17:34 PM »
The mistake you and others make is the assumption that this year's ice is anything like previous years.  Or that this year's climate is anything like previous years.   Or that atmospheric circulation or ocean currents and temperatures are anything like previous years.

You can crunch numbers all you want, but if circumstances in the past in no way resemble current circumstances, then it's just GIGO.

You can't treat a transforming system as if it's a static one and derive anything useful.


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Peter Ellis

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Re: IJIS
« Reply #4648 on: July 23, 2017, 06:20:32 PM »
The mistake you and others make is the assumption that this year's ice is anything like previous years.  Or that this year's climate is anything like previous years.   Or that atmospheric circulation or ocean currents and temperatures are anything like previous years.

You can crunch numbers all you want, but if circumstances in the past in no way resemble current circumstances, then it's just GIGO.

You can't treat a transforming system as if it's a static one and derive anything useful.

We have variations on this post LITERALLY EVERY YEAR.  One year they will be right, much like a stopped clock. When that year comes, don't delude yourself that you deserve credit for your foresight.

jdallen

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Re: IJIS
« Reply #4649 on: July 23, 2017, 07:17:16 PM »
The mistake you and others make is the assumption that this year's ice is anything like previous years.  Or that this year's climate is anything like previous years.   Or that atmospheric circulation or ocean currents and temperatures are anything like previous years.

You can crunch numbers all you want, but if circumstances in the past in no way resemble current circumstances, then it's just GIGO.

You can't treat a transforming system as if it's a static one and derive anything useful.

We have variations on this post LITERALLY EVERY YEAR.  One year they will be right, much like a stopped clock. When that year comes, don't delude yourself that you deserve credit for your foresight.
To underscore Peter's point, I've made similar assertions, presented similar tables of data, made similar dire observations about the ice, only to have it act inconsistent with my predictions.

In short, in spite of the state of the ice, in spite of previous years behavior, because of the state changes taking place in the system at this level of coverage and volume, those statistical analyses lose their predictive power.  What I've seen is an almost "compressive" feedback behavior, where other forces come into play slowing the melt.

My current working hypothesis about this can be summarized thus:  once melt retreats past about 75N over all, the system dynanimics change sharply. My thought is, that open water becomes a buffer which more efficiently and evenly redistributes heat.  I think the dynamics of phase change come into play as well, with heat which previously melted ice, taken up by evaporation, which in turn further contributes to increased albedo.  To summarize, we see increasing feedbacks from different mechanisms that don't exist or are retarded at higher levels of ice coverage.  I think they are the only reason we aren't seeing open water at 90N by early August.
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