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magnamentis

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Re: IJIS
« Reply #4800 on: August 14, 2017, 03:17:23 PM »
By my calculation, the odds of finishing in various places are as follows:

1st:  0%
2nd:  39%
3rd:  11%
4th:  36%
5th:  01%
6th:  12%
7th:  01%
8th or worse:  ~0%

1st 0% would have been the value in 2012 throughout most of the season, what happened then was something new that never happened before,  hence could not be foreseen.

2017 something new could happen as well ( in polls i opted for 2nd all season so no disagreement with that ), just saying, only, even though it can't be predicted, this time most of us are aware of the possibility, (thin, fragmented ice that could be eaten up to zero extent by bottom melt, as well as possible strong winds and wave action )

what i want to say is that 0% chance for 1st i wouldn't sign, (a) for the above reasons and (b) because i generally try to never say 0% and to never say 100% sure if it's avoidable.

i would give a 1st place still a chance or 5-10%, going down by the day of course but for the next 10 days i'd not call it 0% chance.

i know you did the math and they're correct, the above i just wanted to add to round up the picture.

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Re: IJIS
« Reply #4801 on: August 14, 2017, 03:37:08 PM »
Cross-posting from the melt season thread, an update of my chart showing IJIS in Aug-Sept and placement of each year's minimum date.
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Shared Humanity

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Re: IJIS
« Reply #4802 on: August 14, 2017, 04:08:59 PM »
I have characterized the ocean as a massive battery, able to store huge amounts of absorbed energy. This is the primary reason for the distinction between short term and long term equilibrium for any level of atmospheric CO2 IMHO.

Dharma Rupa

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Re: IJIS
« Reply #4803 on: August 14, 2017, 04:10:23 PM »
what i want to say is that 0% chance for 1st i wouldn't sign, (a) for the above reasons and (b) because i generally try to never say 0% and to never say 100% sure if it's avoidable.

I have to agree with this point in particular, but I'd also like to point out that the unknown unknown is the probability that the melting season never (in this Age) ends.

There are two basic theories on how the ice will finally melt out, and I am in the "it won't matter what time of year it is" camp.

Ned W

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Re: IJIS
« Reply #4804 on: August 14, 2017, 08:15:01 PM »
I realize this difficulty in doing the maths, quite properly, consigns my comments to mere opinion and conjecture while yours carry weight.
I would say the opposite -- you have a long history of insightful observations here, which gives your opinions much weight.  The calculations I do are mostly very naive.

Any success that these looks at possible outcomes has had is entirely due to the way that since early June the melting season has been so averagely average (to date). To me this has been the strangest thing about this season.
Yes, it is bizarre how consistently this summer's extent data have followed the "average".  It actually would be unreasonable to expect this level of averageness.

0% would have been the value in 2012 throughout most of the season, what happened then was something new that never happened before,  hence could not be foreseen.
That's more or less true.  At this point in 2012, a similar assessment would have said that the odds of finishing the season at or below 3.18 (the actual min) were around 3%.  Over the course of the next week those odds gradually rose to 10%, then 33% after another week.

But the odds of a new record this year are orders of magnitude lower than the odds of 3.18 were on this date in 2012.  That is to say, tiny.

Espen

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Re: IJIS
« Reply #4805 on: August 15, 2017, 05:28:12 AM »
IJIS:

5,273,676 km2(August 14, 2017)down 48,604 km2 and 3rd lowest measured for the date.
Have a ice day!

Espen

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Re: IJIS
« Reply #4806 on: August 16, 2017, 05:28:20 AM »
IJIS:

5,203,624 km2(August 15, 2017)down 70,052 km2 and 3rd lowest measured for the date.
Have a ice day!

Hyperion

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Re: IJIS
« Reply #4807 on: August 16, 2017, 11:53:46 AM »
<snip. Way off-topic, and too long. I have the entire text of your comment if you'd like me to message it to you so you can edit it and place it in a more appropriate thread. JP>
« Last Edit: August 16, 2017, 01:26:48 PM by Jim Pettit »
Policy: The diversion of NZ aluminum production to build giant space-mirrors to melt the icecaps and destroy the foolish greed-worshiping cities of man. Thereby returning man to the sea, which he should never have left in the first place.
https://en.wikipedia.org/wiki/McGillicuddy_Serious_Party

Hyperion

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Re: IJIS
« Reply #4808 on: August 16, 2017, 01:55:03 PM »
<send Jim a PM, as this is still off-topic; N.>
« Last Edit: August 16, 2017, 02:01:07 PM by Neven »
Policy: The diversion of NZ aluminum production to build giant space-mirrors to melt the icecaps and destroy the foolish greed-worshiping cities of man. Thereby returning man to the sea, which he should never have left in the first place.
https://en.wikipedia.org/wiki/McGillicuddy_Serious_Party

Espen

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Re: IJIS
« Reply #4809 on: August 17, 2017, 06:32:29 AM »
IJIS:

5,136,708 km2(August 16, 2017)down 66,916 km2 and 3rd lowest measured for the date.
Have a ice day!

Coffee Drinker

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Re: IJIS
« Reply #4810 on: August 17, 2017, 06:59:24 AM »
Nice, its already slowing down. A few more weeks and ice will start to grow again.

Peter Ellis

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Re: IJIS
« Reply #4811 on: August 17, 2017, 11:00:39 AM »
Nice, its already slowing down. A few more weeks and ice will start to grow again.
Yes, that's how seasons work. Congratulations for discovering this novel phenomenon, which I propose to call "a year".  I'd question whether a value somewhere between the 2nd and 4th lowest on record is really "nice" though.

Interesting to note that 2017 has been almost precisely the same as 2016 since about half way through June.  Is this simply the "new normal" trajectory?

mmghosh

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Re: IJIS
« Reply #4812 on: August 17, 2017, 11:32:06 AM »
It does seem odd, Peter, with DMI 80 below normal virtually the entire melt season, and comparatively less severe August cyclone season (though there's a couple of weeks to go still).

Thin ice is probably the new normal.

Pmt111500

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Re: IJIS
« Reply #4813 on: August 17, 2017, 12:34:41 PM »
I'm rather surprised by the area still covered by ice, the brine rejection process occurring in the warming 1st year ice could be the factor explaining the surprise.

Ned W

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Re: IJIS
« Reply #4814 on: August 17, 2017, 02:09:27 PM »
2007's minimum was 4.066.  The current projection from the predict-o-matic is 4.067.  Could be a photo finish for a spot on the podium. 

I am curious whether there will be any more century breaks this season.  Until 2015, no year had any century breaks this late except for 2008, which had one.  But then 2015 and 2016 each had two.  All of those were between days 239 and 244. 

Sterks

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Re: IJIS
« Reply #4815 on: August 17, 2017, 04:18:26 PM »
Interesting to note that 2017 has been almost precisely the same as 2016 since about half way through June.  Is this simply the "new normal" trajectory?
I would not question it is the new normal for a cold season over a thin Arctic pack, with warm sun over vast open ocean in the periphery accumulating heat in May and June, for a gradual release during August.
In summary, it is not normal.
Or in other words, can we ever define a "normal"?

Shared Humanity

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Re: IJIS
« Reply #4816 on: August 17, 2017, 08:52:45 PM »
Nice, its already slowing down. A few more weeks and ice will start to grow again.
Yes, that's how seasons work. Congratulations for discovering this novel phenomenon, which I propose to call "a year".  I'd question whether a value somewhere between the 2nd and 4th lowest on record is really "nice" though.

Interesting to note that 2017 has been almost precisely the same as 2016 since about half way through June.  Is this simply the "new normal" trajectory?

I think that, given 2017 is tracking with the bulk of the most recent melt years, it can be considered part of a transitory "normal" trajectory. It also serves to highlight the uniqueness of the 2012 melt season. This may be the new normal trajectory until the next unique melt season which should be an unmitigated disaster.

Watching_from_Canberra

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Re: IJIS
« Reply #4817 on: August 18, 2017, 06:56:39 AM »
Is the global extent graph new?
https://ads.nipr.ac.jp/vishop/#/extent

pauldry600

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Re: IJIS
« Reply #4818 on: August 18, 2017, 09:41:54 AM »
A drop of 30 oddK

Slowdown......

Espen

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Re: IJIS
« Reply #4819 on: August 18, 2017, 03:39:35 PM »
IJIS:

5,103,981 km2(August 17, 2017)down 32,727 km2 and 4th lowest measured for the date.
Have a ice day!

swoozle

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Re: IJIS
« Reply #4820 on: August 18, 2017, 08:13:01 PM »

Espen

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Re: IJIS
« Reply #4821 on: August 20, 2017, 09:18:38 AM »
IJIS:

5,092,819 km2(August 19, 2017)and 4th lowest measured for the date.
Have a ice day!

oren

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Re: IJIS
« Reply #4822 on: August 20, 2017, 09:35:09 AM »
Only 11k in two days. Wow.

Sterks

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Re: IJIS
« Reply #4823 on: August 20, 2017, 10:53:27 AM »
It is the no-GAC effect

DavidR

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Re: IJIS
« Reply #4824 on: August 21, 2017, 08:50:14 AM »
Looking at the extraordinarily low losses (< 80,000 km^2) over the past four days and the broad band of smoke over the Arctic over the same period I am wondering if the smoke is affecting the measurements.  Smoke from forest fires is denser and more pervasive than clouds and it seems possible that  in some way the sensors may be tricked by the denseness of the atmosphere.

If this is the case we will see some dramatic losses soon as the average loss at this time of the year is around 60,000 km^2 per day.
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Coffee Drinker

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Re: IJIS
« Reply #4825 on: August 21, 2017, 10:58:07 AM »
Is it possible that all the smoke is blocking the sun and so reduces melting in the area?

Some of the buoys webcam pictures look extremely dark and gloomy.
http://forum.arctic-sea-ice.net/index.php/topic,327.1750.html

Cato

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Re: IJIS
« Reply #4826 on: August 21, 2017, 12:18:49 PM »
No way in my humble opinion a process like ice melting going on for months can be stopped due to some smoke. In theory, one effect of forest fires is that black soot particles are deposited over the ice thus leading to extra-melting (reduction of albedo). But overall, it is obvious to expect that clouds are much more effective than smoke itself in reducing radiation. And clouds have never been missing in the last few weeks, thus helping to contain the melting.

IMHO the factors which helped avoiding a catastrophic melting have been the following: 1) Cloudy weather 2) Lack of GACs 3) Lower-than-average temperatures in July and August 4) Lack of pre-conditioning due to snow accumulation.

Not necessarily does this flattening of the curve anticipate an imminent and anticipated minimum. On the other hand, the synoptic configuration doesn't look like a catastrophic decrease in ice extension is to be expected, apart for some further and physiological compaction over the CAB. The season is almost over, and even a strong LP wouldn't make such a big damage in a couple of weeks' time, as temperatures are going to decrease significantly and precipitations would be mostly in the shape of snow.

Ned W

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Re: IJIS
« Reply #4827 on: August 21, 2017, 01:29:00 PM »
Extent for 8/20:  5058209 (drop of 34610; 4th lowest for this date).

In the next day or so we should pass the 2009 minimum.

Live version of the predict-o-matic now says 4.22 (range 3.97-4.46).  There is a 52% chance of 4th place and a 33% chance of 6th place.

Extent losses similar to those from 2007-2016 would result in a low of 4.05 to a high of 4.39.


gerontocrat

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Re: IJIS
« Reply #4828 on: August 21, 2017, 01:54:14 PM »
On Aug 14th I foolishly wrote:-
" I will be surprised if this end of season comes up with a surprise."

And now:-
Until then conditions for melting were negative to average but extent loss cheerfully pottered along.
Now:-
- Arctic Ocean SST anomalies have been and are high,
- DMI 80+ N has ticked up a degree or two from below average,
- cci-reanalyzer has had the Arctic temperature anomaly at about 1 degree celsius above average.

And extent loss is well below average. 4.2 million is now the result of average extent loss from now to minimum, with less than 4 weeks to go.
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DavidR

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Re: IJIS
« Reply #4829 on: August 21, 2017, 03:22:10 PM »
Is it possible that all the smoke is blocking the sun and so reduces melting in the area?

Some of the buoys webcam pictures look extremely dark and gloomy.
http://forum.arctic-sea-ice.net/index.php/topic,327.1750.html
This seems highly unlikely for two reasons:
1. A lot of melt at this time of the year is bottom melt from the water which is unlikely to have changed much,
2. The Smoke doesn't block that much of the sun's radiation.

On the other hand if the instruments are designed to look through cloud to make their estimates and the sky is full of smoke and particulate matter that has a quite different structure than cloud it is possible that they are not reporting accurately on what is happening under the cloud.

The average daily loss at this time of the year is greater than 55000 km^2 and the smallest 4 day loss in August to this date, prior to yesterday, (119345 in 2003) was more than 50% greater than todays figure (78499).  My gut feeling is that the smoke is hiding the reality of what is happening at sea level. I wouldn't be surprised to see a couple of big century breaks over the next week if the smoke clears.
« Last Edit: August 21, 2017, 03:27:14 PM by DavidR »
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Espen

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Re: IJIS
« Reply #4830 on: August 21, 2017, 04:35:51 PM »
IJIS:

5,058,209 km2(August 20, 2017)down 34,610 km2 and 4th lowest measured for the date.
Have a ice day!

weatherdude88

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Re: IJIS
« Reply #4831 on: August 21, 2017, 05:04:03 PM »
We are currently in an unprecedented slow down in this melting season. Looking at JAXA sea ice extent data for the past 5 days (8.14-8.20), here is how this year compares to previous years. All of this in a time frame were weather was considered unfavorable by some. Where is the heat? 




78499  Kilometers Squared (2017)    
250806 Kilometers Squared (2016)
271380 Kilometers Squared (2015)    
201212 Kilometers Squared (2014)
170241 Kilometers Squared (2013)
323143 Kilometers Squared (2012)    
214782 Kilometers Squared (2011)    
171913 Kilometers Squared (2010)    
242082 Kilometers Squared (2009)    
235464 Kilometers Squared (2008)
209292 Kilometers Squared (2007)    
236247 Kilometers Squared (2006)    
174575 Kilometers Squared (2005)    
294866 Kilometers Squared (2004)    
125356 Kilometers Squared (2003)    
223099 Kilometers Squared (2002)    
207152 Kilometers Squared (2000's Average)
141827 Kilometers Squared (1990's Average)    
106000 Kilometers Squared (1980's Average)

Sterks

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Re: IJIS
« Reply #4832 on: August 21, 2017, 06:39:22 PM »
We are currently in an unprecedented slow down in this melting season. Looking at JAXA sea ice extent data for the past 5 days (8.14-8.20), here is how this year compares to previous years. All of this in a time frame were weather was considered unfavorable by some. Where is the heat?
Not sure if we are reading the same forum. I can't speak but for myself, and found the forecasts as "neither fish nor fowl" a few days ago just as "the slowdown" had started ...which common sense says is a weather friendly for ice at this time of the year, see below.

But I observe in the forecasts, may be wrong, some potential for compaction starting now. It is not very strong but might persist for a week.

The most recent runs from ECMWF and GFS indicates more high pressure dominated weather as the melting season is getting close to the end. If this forecast had been in July and not the second half of August the sea ice would have faced seriously melting.

As my mother would have said in her tongue this weather, now, does not bring "Ni chicha ni limoná" for the first days but looks interesting in the longer range, with potential for compaction, like wrapping up things.
In 20 days tops, this is over.
« Last Edit: August 21, 2017, 06:44:26 PM by Sterks »

Cid_Yama

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Re: IJIS
« Reply #4833 on: August 21, 2017, 07:19:38 PM »
We had people declaring the end of the melt season around this time last year only to see the ice fall off a cliff the last week of August.

It's not over 'til it's over.  And I'm not seeing any slow down.  We just had a century drop in Area yesterday.

Wipneus AMSR2:

Quote
Update 20170820.

Extent: -20.8 (+253k vs 2016, +55k vs 2015, -488k vs 2014, -524k vs 2013, +993k vs 2012)
Area: -125.0 (+495k vs 2016, +134k vs 2015, -643k vs 2014, -658k vs 2013, +858k vs 2012)

http://forum.arctic-sea-ice.net/index.php/topic,382.msg126013.html#msg126013
« Last Edit: August 21, 2017, 07:28:07 PM by Cid_Yama »
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Pavel

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Re: IJIS
« Reply #4834 on: August 21, 2017, 07:52:05 PM »
Too less of easy ice to melt remain. I don't expect any significan decline further.
Quote
Where is the heat?
The main thing of this melting season could be the Arctic SSTs. It's worse than last year and we remember what was the 2016 fall

Feeltheburn

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Re: IJIS
« Reply #4835 on: August 22, 2017, 04:23:13 AM »
We had people declaring the end of the melt season around this time last year only to see the ice fall off a cliff the last week of August.

It's not over 'til it's over.  And I'm not seeing any slow down.  We just had a century drop in Area yesterday.


The cliff last year was the result of an arctic cyclone in August. Is there one forcast or likely this year? Without it we will not likely have a repeat of last year's cliff.
Feel The Burn!

Feeltheburn

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Re: IJIS
« Reply #4836 on: August 22, 2017, 04:49:43 AM »
We are currently in an unprecedented slow down in this melting season. Looking at JAXA sea ice extent data for the past 5 days (8.14-8.20), here is how this year compares to previous years. All of this in a time frame were weather was considered unfavorable by some. Where is the heat?


I doubt whether 5 days are statistically significant since the ability to accurately count pixels and determine ice extent at a single point in time is somewhat limited (e.g., due to cloud cover and polynyas) and more accurate when averaged over longer periods of time. Still, in harmony with the propensity of some to proclaim that single events are climate not weather, I can't blame anyone for noticing the apparent abrupt slowdown in melting (although I can see it suddenly accelerating without notice).
Feel The Burn!

jdallen

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Re: IJIS
« Reply #4837 on: August 22, 2017, 05:16:42 AM »
Too less of easy ice to melt remain. I don't expect any significan decline further.
Quote
Where is the heat?
The main thing of this melting season could be the Arctic SSTs. It's worse than last year and we remember what was the 2016 fall
The effect of insolation on the ice North of 80 is pretty much done, so the end of season story will be whether or not heat loss out of the main pack will be fast enough that it can compensate for bottom melt.

As various images indicate, there is a whole lot of extent which scarcely qualifies as such.  That what is in play.
This space for Rent.

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Re: IJIS
« Reply #4838 on: August 22, 2017, 08:00:52 AM »
(Ignore this as my graph ran away with me producing a spurious additional value. The actual five day  loss was (-88801) Still lowest for the  month to date, but  not  as low as I said.)
 
The five day extent  loss (-56074 km^2) is now the second lowest August loss in the IJIS record since 2002. The lowest (-16573) was on August  31 , 2006.  This is three standard deviations less than the average loss at this stage of the year.

While anything can happen in the Arctic, this anomaly demands an explanation.   
« Last Edit: August 23, 2017, 06:53:45 AM by DavidR »
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arctic-watcher

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Re: IJIS
« Reply #4839 on: August 22, 2017, 08:12:16 AM »
What was the explanation in 2006? 

Lord M Vader

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Re: IJIS
« Reply #4840 on: August 22, 2017, 08:17:53 AM »
Very little compaction perhaps?

miki

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Re: IJIS
« Reply #4841 on: August 22, 2017, 09:15:42 AM »
Or perhaps the heat is going in the water, the extended ice soup being the lid. Thinking of 2007 september minimum... I wonder if we'll dodge the cannon ball next year...

Cato

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Re: IJIS
« Reply #4842 on: August 22, 2017, 10:29:43 AM »
Guys, sometimes the easiest explanation is the most reliable: it's the principle of the Razor of Occam at the end of the day. The summer has been rather cool over the arctic and this is fact. There was no significant pre-conditioning, and this is another fact. The synoptic configuration has been quite benign so far, and this is another fact.

For a couple of months I've been stating that synoptic configuration was favorable to ice preservation: lack of strong winds, plenty of clouds in July and August, lack of significant cyclones at the end of August. Nobody should really be surprised by a slowing down of the melting rate in this period.

I think that nobody is immune to confirmation bias: we all know that the trend is clear and is to ice decrease both in extension and volume. This doesn't imply, however, that every year, and every month of that year, there will be a new record-low, or an exceptional melting or something has never been seen before.  2013 should have thought us something in this regard. As Neven has explained very well, 2017 has just dodged a canonball. There is no such thing as "hidden warming", forest fires or whatsoever: summer 2017 has just been very benevolent to the ice in terms of weather and temperatures, that's it. But the trend is clear and is to the low.

Whatever the end of this race, be it a 2nd place or a 5th place, this is not going to change anything in the long term, unfortunately. Which is the only thing that really matters.

Ned W

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Re: IJIS
« Reply #4843 on: August 22, 2017, 01:09:14 PM »
Extent for 8/21:  5047907 (drop of 10302; 5th lowest for this date).

2017 just passed the 2009 minimum.

Live version of the predict-o-matic now says 4.26 (range 4.01-4.50).  There is a 45% chance of 4th place and a 43% chance of 6th place.

Extent losses similar to those from 2007-2016 for the remaining days of the season would result in a 2017 minimum of 4.09 to 4.44.

Espen

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Re: IJIS
« Reply #4844 on: August 22, 2017, 04:03:51 PM »
IJIS:

5,047,907 km2(August 21, 2017)down 10,302 km2 and 5th lowest measured for the date.
Have a ice day!

Ned W

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Re: IJIS
« Reply #4845 on: August 23, 2017, 11:58:03 AM »
Extent for 8/22:  5003285 (drop of 44622; 5th lowest for this date).

Live version of the predict-o-matic now says 4.27 (range 4.03-4.51).  There is a 41% chance of 4th place and a 48% chance of 6th place.  Complete list of odds:

1st place:  0%
2nd place:  2%
3rd place:  3%
4th place: 41%
5th place:  4%
6th place:  48%
7th place:  3%
8th place or higher: 0%

Extent losses similar to those from 2007-2016 for the remaining days of the season would result in a 2017 minimum of 4.11 to 4.45.

Pi26

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Re: IJIS
« Reply #4846 on: August 23, 2017, 01:52:32 PM »
Extent for 8/22:  5003285 (drop of 44622; 5th lowest for this date).

Live version of the predict-o-matic now says 4.27 (range 4.03-4.51).  There is a 41% chance of 4th place and a 48% chance of 6th place.  Complete list of odds:

1st place:  0%
2nd place:  2%
3rd place:  3%
4th place: 41%
5th place:  4%
6th place:  48%
7th place:  3%
8th place or higher: 0%

Extent losses similar to those from 2007-2016 for the remaining days of the season would result in a 2017 minimum of 4.11 to 4.45.

That output totally works against my logic module  :o ;)
« Last Edit: August 23, 2017, 02:01:03 PM by Pi26 »

Ned W

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Re: IJIS
« Reply #4847 on: August 23, 2017, 03:00:06 PM »
Hmmm.  What would be better?

Pi26

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Re: IJIS
« Reply #4848 on: August 23, 2017, 03:16:10 PM »
Hmmm.  What would be better?

Is odd for place 5 so small, because it is has such a small range?

Ned W

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Re: IJIS
« Reply #4849 on: August 23, 2017, 03:20:17 PM »
Yes, exactly.  Currently, 2015 and 2011 are in 4th and 5th places, respectively.  Their minimums were very very close:

2015   4.257
2011   4.269

There's just not much of a gap for 2017 to fit into there.  That said ... the current best estimate for 2017 is really close to that gap.  So it could thread that needle. 

But either 4th or 6th place is more likely, just because there's more "space" there.