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gerontocrat

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Re: IJIS
« Reply #4250 on: May 15, 2017, 02:09:57 PM »
we are still 400.000 km2 lower than 2012 and 140.000 km2 lower than 2007 at this time of the year, which were lowest and 3rd lowest ever recorded, so based on that still 'on schedule' for a new record, around 2.6/2.7k km2

Or we are ~800.000 above 2016, so we won't get below 5 million km2 this year.

Or the gap with the 2000's average is halved in 2 months (800k earlier, 400k now), so in 4 months (2*400k) we will be 400k higher than the 2000's average, so around 6 million km2


Just pick the one you want, they are all based on the same set of numbers ;)
But you can look at probabilities of various outcomes by comparing required melting for an outcome against historical actual melting rates. I think that has some validity for a risk analysis.  But I am too lazy to do it.

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Jim Pettit

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Re: IJIS
« Reply #4251 on: May 15, 2017, 03:57:31 PM »
Some decent drops the last two days but we are still 6th lowest and a whooping 800K behind 2016... Even 2004 had lower extent at this date of year.

2016 isn't a concern, if you ask me; given 2016's very low June decrease and the state of this year's ice, that 800k extent gap will disappear within the next 5-6 weeks. (Between May 31 and June 15, last year dropped by just 541k km2, while 2012 lost an amazing 1.347M--a "gap closing" of over 800k.)

My hunch is that 2017 will spend most of July and August in either first or second place.

Random_Weather

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Re: IJIS
« Reply #4252 on: May 15, 2017, 04:17:18 PM »
@ Jim

Y, as said in another thread, its all about summer saison, you can start in May with record low ice and dont get a record low in september, on the other hand, if ice undergo in summer record low, its likly it will does in september. In easy words, its a cascading effect in summer, if melt is weak during early summer (June) it would trigger enough feedback that prevent a new record, or its strong it will likly force a new minimum.

This weakness of melt in last June, is likly the cause of not setting a new record in 2016

gerontocrat

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Re: IJIS
« Reply #4253 on: May 15, 2017, 04:38:12 PM »
I thought to myself, (Qu1) how much additional melting from May 14 is required to get to the 2012 or the 2007 sea ice extent minimum. Then I asked myself (Qu2), in previous years, what melting has happened from May 14 to those years' minima. Answer in table below (Jaxa data).

Only in 2012 was the additional melting more than required for 2017 to be a new record minimum, and for the 2007 result only in 2012 and 2007. I also look at the images and data all over ASIF, and yes, they do show what a mess the arctic ice is in. This little table does, however, give some indication of the extent to which the rest of the melting season would have to be out of the ordinary for a record low sea ice extent. ( Needs must I now duck).

Qu1.
 For 2012 Result     8,891,439    
 For 2007 Result     8,003,155    
Qu2.
 Previous Years' Actual melting May 14 to minimum       
1980's Average    6,088,155    
1990's Average    6,373,434    
2000's Average    6,987,172    
2003    6,544,668    
2004    6,324,802    
2005    7,211,275    
2006    6,354,975    
2007    8,141,722    
2008    7,956,679    
2009    7,656,049    
2010    7,723,227    
2011    7,886,188    
2012    9,282,412    
2013    7,811,689    
2014    7,175,806    
2015    7,634,353    
2016    7,276,462    
"Para a Causa do Povo a Luta Continua!"
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Bill Fothergill

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Re: IJIS
« Reply #4254 on: May 15, 2017, 05:12:40 PM »
Some decent drops the last two days but we are still 6th lowest and a whooping 800K behind 2016... Even 2004 had lower extent at this date of year.

2016 isn't a concern, if you ask me; given 2016's very low June decrease and the state of this year's ice, that 800k extent gap will disappear within the next 5-6 weeks. (Between May 31 and June 15, last year dropped by just 541k km2, while 2012 lost an amazing 1.347M--a "gap closing" of over 800k.)

My hunch is that 2017 will spend most of July and August in either first or second place.

Although 2017 might be currently "languishing" in 6th lowest position, when the data for May 14th gets factored in, the current SIE is only ~ 90k sq kms higher than the 3rd lowest for the date (2006), and ~ 180k sq kms higher than that recorded in 2015, which is the 2nd lowest for the date.

As at May 14, and just considering the period stretching from 2004 until now, 2012 has the 2nd highest SIE for the date in the IJIS/ADS database - and I think we all know what happened a bit later in that year.

magnamentis

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Re: IJIS
« Reply #4255 on: May 15, 2017, 05:36:00 PM »
we are still 400.000 km2 lower than 2012 and 140.000 km2 lower than 2007 at this time of the year, which were lowest and 3rd lowest ever recorded, so based on that still 'on schedule' for a new record, around 2.6/2.7k km2

Or we are ~800.000 above 2016, so we won't get below 5 million km2 this year.

Or the gap with the 2000's average is halved in 2 months (800k earlier, 400k now), so in 4 months (2*400k) we will be 400k higher than the 2000's average, so around 6 million km2


Just pick the one you want, they are all based on the same set of numbers ;)
But you can look at probabilities of various outcomes by comparing required melting for an outcome against historical actual melting rates. I think that has some validity for a risk analysis.  But I am too lazy to do it.

that's exactly his and my point, the current extent ist totally irrelevant, mentioning it is useless and just cloggs the thread while anyone reading here will know that anyways because i'm sure that close to 100% of all readers are consulting the approprate graphs and stats every day.

and this is why there are reactions on such posts, for someone who is seeking real info, something that adds to the learning and understanding curve this is annoying because one has to read 9 such posts before reaching a valueable contribution. just my 2cts and i know that others see this different and many like this kind of chatter while i think there are better places to chat, facebook and the likes.

be cause

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Re: IJIS
« Reply #4256 on: May 15, 2017, 06:10:46 PM »
but when A-team said the same ...
 at least the figures offered above add clarity to the valuelessness of extrapolation at this stage of the season .
2007 + 5 = 2012 + 4 = 2016 + 3 = 2019 + 2 = 2021 + 1 .. you gotta laugh .. :)

gerontocrat

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Re: IJIS
« Reply #4257 on: May 15, 2017, 07:02:55 PM »
Hullo magnamentis.
You write that the current extent is totally useless on the thread for posting current extent data.
"Para a Causa do Povo a Luta Continua!"
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Espen

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Re: IJIS
« Reply #4258 on: May 15, 2017, 07:27:53 PM »
IJIS:

12,068,894 km2(May 14, 2017)and 6th lowest measured for the date.
Have a ice day!

oren

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Re: IJIS
« Reply #4259 on: May 15, 2017, 08:18:36 PM »
120k in two days.

Bill Fothergill

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Re: IJIS
« Reply #4260 on: May 15, 2017, 09:54:26 PM »
As there is not a great deal of movement on the IJIS/JAXA/ADS daily numbers at the moment, I thought I would re-post an updated version of the rolling-365 day average SIE chart which was posted near the end of January.

Three features of the data are readily apparent in the chart...

1) there is an unambiguous overall downward trend in annual average sea ice extent;

2) there is the appearance of an approximately 5-year cycle superimposed on the longer downward trend, and;

3) the downward spiral has recently been halted, albeit for what could be a brief period. (N.B. Once the data for the 16th, or possibly 17th, of May is at hand, the rolling average will be at its highest level since the end of 2016.)


The reasons behind points (1) and (3) are pretty straightforward, and therefore will be addressed first.

To all bar the inhabitants of Flatland, point (1) is clearly the direct consequence of the planetary energy imbalance due to the ~ 100ppm(v) rise in atmospheric CO2 levels since Charles Keeling started tracking these values nearly 60 years ago.

The current slight rise in the curve - point (3) - can be characterised as noise, but it is nonetheless possible to explain this in part. When any rolling 365-day average value is plotted, the "instantaneous" gradient of the curve is determined by a very simple inequality. Except for the vanishingly remote chance of Day X in any year having exactly the same value as Day X of the previous year, the inequality can exist in either of two, mutually exclusive, forms...

Day X(Year N) > Day X(Year N-1),
OR
Day X(Year N) < Day X(Year N-1)

Whenever the Day X(Year N-1) value represents a genuine statistical outlier, then it is axiomatic that the Day X(Year N) value is generally likely to be less extreme, in other words, it is likely to demonstrate regression toward the mean.

That is exactly the situation we are seeing at present, and are going to be seeing for some time to come. When I did a snapshot on May 11th, this is what the rolling-365 day average would be seeing over the next 12 months...

181 days in which the Day X(Year N-1) value was the lowest on record
76 days in which the Day X(Year N-1) value was the 2nd lowest on record
72 days in which the Day X(Year N-1) value was the 3rd lowest on record

(NB Obviously the likelihood of regression to the mean taking place is affected by any developments in the shape of the overall trend.)

Graph 1 & 2 (below) are a matching pair which only differ in the Y-axis; the first shows the actual value of the rolling 365-day average extent, whilst its partner shows this as an anomaly from the Jan 2006 - December 2015 mean.

Graph 3 (bar chart) puts the above into a bit more context by also including overall means for the 1980's, 1990's, 2000's and 2010-2016. Column 5 shows the highest value for the rolling average attained over the last decade, and the remaining columns show the local minima recorded at the turning points in the first 2 graphs.


Moving onto point (2) - the putative approximately 5-year cycle superimposed upon the overall declining trend in sea ice extent. This is a topic that has been (and is being) discussed on the ASIB. My own view - for what little that is worth - was that the period under examination was far too short to determine if this was a genuine recurring pattern.

Given the current lack of activity in SIE numbers, I downloaded the .csv file from the ADS version 2 site - as this starts from 1979, rather than 2003 as per ADS version 1 - with the intention of extending the chart back by about 25 years. However, owing to the number of data drops during the early stages (and the fact that daily measurements  only began during 1987) it was easier to use the NSIDC monthly values as a reasonable proxy.

This is shown on graph 4, and, to my surprise, with the data stretched back to ~ 1980, there is still some semblance of a recurring pattern.

Given the approximately 5 year periodicity of this possibly cyclic phenomenon, it seemed like an idea to map - for starters - the Nino 3.4 anomalies. As with the SIE data, this was smoothed to give a rolling 12-month average, and was then lagged by 6, 12, 18, 24 and 30 month periods. This is shown as graph 5.

The Nino anomaly values are shown on a secondary Y-axis which has been inverted to display +ve anomalies as downward pointing excursions. It was hoped that by implementing this inversion, dips in the SIE might line up with el Nino events, but any such correlation escapes my Mk I eyeball. (Although, following the successful operation last year, I should perhaps call it a Mk II?)

Whilst graph 5 singularly fails to demonstrate any obvious correlation between el Nino/la Nina patterns and sea ice extent behaviour, it's been included in the hope that it may, nonetheless, give an idea to someone. Hopefully, at least two of the regular contributors to the ASIB might have some words offer, as we have differing views on the subject.

Espen

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Re: IJIS
« Reply #4261 on: May 16, 2017, 05:23:34 AM »
IJIS:

12,020,242 km2(May 15, 2017)down 48,652 km2 and 5th lowest measured for the date.

Sorry Espen, but I get it to be 5th lowest for the date behind 2016, 2015, 2006 and 2004.

Sorry about that ;)
« Last Edit: May 16, 2017, 07:34:52 PM by Espen »
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Lord M Vader

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Re: IJIS
« Reply #4262 on: May 16, 2017, 08:49:27 AM »
Sorry Espen, but I get it to be 5th lowest for the date behind 2016, 2015, 2006 and 2004.

Tor Bejnar

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Re: IJIS
« Reply #4263 on: May 16, 2017, 04:40:44 PM »
I think sometimes there is a difference between 'day of year' and 'date'.
Arctic ice is healthy for children and other living things because "we cannot negotiate with the melting point of ice"

Espen

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Re: IJIS
« Reply #4264 on: May 17, 2017, 05:30:15 AM »
IJIS:

11,929,542 km2(May 16, 2017)down 90,700 km2 and 5th lowest measured for the date.
Have a ice day!

Pmt111500

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Re: IJIS
« Reply #4265 on: May 17, 2017, 08:46:01 AM »
IJIS:

11,929,542 km2(May 16, 2017)down 90,700 km2 and 5th lowest measured for the date.
Is this the largest drop for the day of the year? #absolutelynecessaryordinals #notthefastestidontcare

Sorry, the denialist-me speaking.

Bill Fothergill

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Re: IJIS
« Reply #4266 on: May 17, 2017, 10:00:07 AM »

Is this the largest drop for the day of the year?

From March 15 to 16, -112k
From April 04 to 05, -101k

However, the NSIDC daily went up 8k between the 14th & 15th May, so it will be interesting to see what happens (in about 4 hours time) when their daily figures get updated.
« Last Edit: May 17, 2017, 10:05:21 AM by Bill Fothergill »

Feeltheburn

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Re: IJIS
« Reply #4267 on: May 17, 2017, 10:33:34 PM »
Hullo magnamentis.
You write that the current extent is totally useless on the thread for posting current extent data.

LOL!
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gregcharles

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Re: IJIS
« Reply #4268 on: May 18, 2017, 01:55:38 AM »

Is this the largest drop for the day of the year?

From March 15 to 16, -112k
From April 04 to 05, -101k

However, the NSIDC daily went up 8k between the 14th & 15th May, so it will be interesting to see what happens (in about 4 hours time) when their daily figures get updated.

In case you meant drops for May 16 from any year, then the biggest drop was -105k from 2012.

Espen

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Re: IJIS
« Reply #4269 on: May 18, 2017, 05:26:34 AM »
IJIS:

11,861,030 km2(May 17, 2017)down 68,512 km2 and 4th lowest measured for the date.
« Last Edit: May 18, 2017, 04:07:54 PM by Espen »
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Lord M Vader

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Re: IJIS
« Reply #4270 on: May 18, 2017, 07:21:58 AM »
Yes, and we are now 4th lowest for the date. Might catch up with 2006 by the next few days. 2015 is a different task, might take over the second place by the first week in June when SIE stalled in 2015.

Bill Fothergill

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Re: IJIS
« Reply #4271 on: May 18, 2017, 04:27:45 PM »

Is this the largest drop for the day of the year?

From March 15 to 16, -112k
From April 04 to 05, -101k

However, the NSIDC daily went up 8k between the 14th & 15th May, so it will be interesting to see what happens (in about 4 hours time) when their daily figures get updated.

In case you meant drops for May 16 from any year, then the biggest drop was -105k from 2012.

Oops.  :-[

Re-reading the original question, I think my interpretation was incorrect.

I thought the questioner asked if the drop of 90,700 sq kms had been the largest to date for this year.

mea culpa   :-[


Yes, and we are now 4th lowest for the date. Might catch up with 2006 by the next few days. 2015 is a different task, might take over the second place by the first week in June when SIE stalled in 2015.

Yep, two days of -60K sq kms would put 2017 fractionally below 2006.

However, today's NSIDC daily only dropped by four thousand sq kms.

Espen

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Re: IJIS
« Reply #4272 on: May 19, 2017, 05:24:55 AM »
IJIS:

11,825,978 km2(May 18, 2017)down 35,052 km2 and 4th lowest measured for the date.
« Last Edit: May 19, 2017, 03:37:38 PM by Espen »
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Espen

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Re: IJIS
« Reply #4273 on: May 20, 2017, 08:36:58 AM »
IJIS:

11,792,207 km2(May 19, 2017)33,771  km2 and 5th lowest measured for the date.
Have a ice day!

Jim Pettit

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Re: IJIS
« Reply #4274 on: May 20, 2017, 03:39:42 PM »
IJIS:

11,792,207 km2(May 19, 2017)33,771  km2 and 5th lowest measured for the date.

IJIS should be back in third within a week, and in second (or first) within three.

gregcharles

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Re: IJIS
« Reply #4275 on: May 20, 2017, 11:44:46 PM »
Third by May 26? It's definitely possible, but unless the next week averages losses of a bit over 50K per day, 2017 will be in sixth place by then. We'll see!

Espen

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Re: IJIS
« Reply #4276 on: May 21, 2017, 10:32:09 AM »
IJIS:

11,774,477 km2(May 20, 2017)down 17,730 km2 and 5th lowest measured for the date.
Have a ice day!

Quantum

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Re: IJIS
« Reply #4277 on: May 21, 2017, 03:17:01 PM »
Forgive my ignorance but is there a correlation between low IJIS drops on one day and high drops on the next. I've noticed that you often get very low drops (or even gains) that proceed very high ones (including centuries). Is there something to this or is it just confirmation bias?

Shared Humanity

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Re: IJIS
« Reply #4278 on: May 21, 2017, 04:32:35 PM »
Forgive my ignorance but is there a correlation between low IJIS drops on one day and high drops on the next. I've noticed that you often get very low drops (or even gains) that proceed very high ones (including centuries). Is there something to this or is it just confirmation bias?

I can imagine a mechanism that might explain this (thin ice on the margins spreading out into empty seas where it is exposed to open, warmer waters and melts vigorously) but I would be speculating.

Peter Ellis

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Re: IJIS
« Reply #4279 on: May 21, 2017, 10:55:50 PM »
Much simpler explanation is some kind of transient error (clouds concealing open water) on one day that isn't present the next day.  Reading too much into the tealeaves of daily changes is probably unwise.

Espen

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Re: IJIS
« Reply #4280 on: May 22, 2017, 05:27:36 AM »
IJIS:

11,766,129 km2(May 21, 2017)down 8,348 km2 and 6th lowest measured for the date.
Have a ice day!

gregcharles

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Re: IJIS
« Reply #4281 on: May 22, 2017, 07:19:11 AM »
Seventh actually. 2010 and 2011 are squeezed together.

be cause

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Re: IJIS
« Reply #4282 on: May 22, 2017, 11:34:04 AM »
.. and how sure we all were that 2017 would be leading the pack (or top 3 ) all the way .. I guess june will prove a little more exciting on the extent front .. b.c.
2007 + 5 = 2012 + 4 = 2016 + 3 = 2019 + 2 = 2021 + 1 .. you gotta laugh .. :)

Jim Pettit

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Re: IJIS
« Reply #4283 on: May 22, 2017, 12:54:55 PM »
.. and how sure we all were that 2017 would be leading the pack (or top 3 ) all the way .. I guess june will prove a little more exciting on the extent front .. b.c.

I don't know that "we all were" sure of that, nor even most of us. In fact, I recall multiple comments noting that 2017 would have a difficult time keeping up with 2016, at least into June. And I also recall multiple comments--both this year and others--noting that late spring extent is a very poor metric upon which to base one's prediction for the summer minimum. To wit: 2012 SIE had more than a million square kilometers more ice on this date than did 2016--yet 2012 bottomed out 839k lower than did 2016.

Patience...

pauldry600

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Re: IJIS
« Reply #4284 on: May 22, 2017, 01:38:52 PM »
hear hear

3.7m will still be the min
 8)

Richard Rathbone

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Re: IJIS
« Reply #4285 on: May 22, 2017, 02:20:34 PM »
Forgive my ignorance but is there a correlation between low IJIS drops on one day and high drops on the next. I've noticed that you often get very low drops (or even gains) that proceed very high ones (including centuries). Is there something to this or is it just confirmation bias?

Its there, but its an artefact of the data being a 2-day running average.

Espen

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Re: IJIS
« Reply #4286 on: May 23, 2017, 05:31:10 AM »
IJIS:

11,715,601 km2(May 22, 2017)down 50,528 km2 and 7th lowest measured for the date.
Have a ice day!

Espen

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Re: IJIS
« Reply #4287 on: May 24, 2017, 05:26:17 AM »
IJIS:

11,660,438 km2(May 23, 2017)down 55,163 km2 and 7th lowest measured for the date.
Have a ice day!

Espen

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Re: IJIS
« Reply #4288 on: May 25, 2017, 10:25:42 AM »
IJIS:

11,600,754 km2(May 24, 2017)down 59,684 km2 and 7th lowest measured for the date.
Have a ice day!

Espen

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Re: IJIS
« Reply #4289 on: May 26, 2017, 10:36:13 AM »
IJIS:

11,544,894 km2(May 25, 2017)down 55,860 km2 and 6th lowest measured for the date.
Have a ice day!

pauldry600

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Re: IJIS
« Reply #4290 on: May 26, 2017, 11:23:41 AM »
How is it surviving?

This is truly not representative of the real state of the ice.

Its in mulch.

It could be in a very very sorry state by September

There are cracks everywhere and a small danger the whole pack could get detached from the coasts as Greenland which was the only hope is getting warmer by the year and it used to hold the whole ice in place.

oren

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Re: IJIS
« Reply #4291 on: May 26, 2017, 11:26:11 AM »
I think a lot of export of MYI into the Atlantic side over the winter is keeping up extent now. It may hold for a while longer.

mmghosh

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Re: IJIS
« Reply #4292 on: May 26, 2017, 03:00:34 PM »
Probably setting up for the June cliff, per 5-year cycle.

magnamentis

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Re: IJIS
« Reply #4293 on: May 26, 2017, 04:03:47 PM »
I think a lot of export of MYI into the Atlantic side over the winter is keeping up extent now. It may hold for a while longer.

that's it in short and it's the key difference to previous years, thanks for pointing this out, i always need too many words to make my point, always happy to see those who are able to provide key information short and in a concise manner. :-) nice weekend @all

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Re: IJIS
« Reply #4294 on: May 26, 2017, 08:39:14 PM »
How is it surviving?

This is truly not representative of the real state of the ice.

Its in mulch.

It could be in a very very sorry state by September

There are cracks everywhere and a small danger the whole pack could get detached from the coasts as Greenland which was the only hope is getting warmer by the year and it used to hold the whole ice in place.
No matter how broken up by winds it has been so far, or how thin it is, it's still below freezing over much of the Arctic. Ice won't melt unless it exceeds the freezing point somehow, whether through bottom melt or surface melt or rain.

We're in the time of year when the high Arctic isn't refreezing or melting just yet, it's just sitting there waiting for higher temperatures.

StopTheApocalypse

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Re: IJIS
« Reply #4295 on: May 26, 2017, 08:43:25 PM »
No matter how broken up by winds it has been so far, or how thin it is, it's still below freezing over much of the Arctic. Ice won't melt unless it exceeds the freezing point somehow, whether through bottom melt or surface melt or rain.

This isn't quite true, as insolation can make up the difference of the energy being lost by the ice to the air, I think. That is, it's possible for the ice to be warmer than the air above it with help from the sun.

Darvince

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Re: IJIS
« Reply #4296 on: May 26, 2017, 09:08:50 PM »
The ice is then above the freezing point, is it not?

StopTheApocalypse

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Re: IJIS
« Reply #4297 on: May 26, 2017, 09:28:18 PM »
Yes! But you said "over much of the arctic". I assumed you were referring to air temperatures, not ice temperatures.

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Re: IJIS
« Reply #4298 on: May 26, 2017, 10:20:30 PM »
The ice is then above the freezing point, is it not?

i might be ignorant but as to my knowledge  there is no ice above freezing point, ice above freezing point is liquid water, there can be melt ponds (water puddles) on the ice surface and that water can indeed be above freezing point (has to be somehow LOL) but not the ice temperature itself.

the fact that ice can be warmer than the air above it is IMO only possible if the air is below 0C, if the air has 0C for example, warmer ice would be above 0C  and paragraph 1 applies.

there might be professionals roaming this forum who know better or can explain better, would be nice if one of them would either confirm this assumption or negate it but then with explanation please so we can learn something, this just in case that my assumption is wrong.
« Last Edit: May 28, 2017, 11:54:27 AM by magnamentis »

Darvince

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Re: IJIS
« Reply #4299 on: May 26, 2017, 10:24:49 PM »
The ice is then above the freezing point, is it not?

i might be ignorant but as to my knowledge  there is no ice above freezing point, ice above freezing point is liquid water, there can be melt ponds (water poodles) on the ice surface and that water can indeed be above freezing point (has to be somehow LOL) but not the ice temperature itself.

the fact that ice can be warmer than the air above it is IMO only possible if the air is below 0C, if the air has 0C for example, warmer ice would be above 0C  and paragraph 1 applies.
You're right, there is no ice above freezing point, my bad, I should have said melting  :P

Yes! But you said "over much of the arctic". I assumed you were referring to air temperatures, not ice temperatures.
However, the high Arctic shows no signs of melting just yet so I do not think it is that large of an effect.

https://go.nasa.gov/2r6Atdx
You can see where there is melting by the areas tinted darker blue. Be wary, however, that ice decayed even further and drained of melt ponds (in James Bay only) will be lighter blue again.