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12Patrick

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Re: The 2015 melting season
« Reply #2700 on: July 28, 2015, 09:47:17 PM »
Is this evidence of the arctic dipole already kicking in as of yesterday?

Tommy

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Re: The 2015 melting season
« Reply #2701 on: July 28, 2015, 09:49:41 PM »
Quote
It never fails to astound me that so many people recognize expertise, skills, and knowledge in other areas yet easily dismiss science and scientists if they find that the information contradicts their beliefs. --
helorime


I was protesting pollution and fighting the precursors to climate change denial when you was likely a baby. But, I can show you hundreds of studies published in respected peer-reviewed journals, decade after decade (nothing to do with climate or environment though) conducted in a myriad of respected universities and academic institutions around the world, on one specific subject alone, and still repeating the same fascinating results today, in journal after journal, that, judging by the tone of your first post, I suspect you will probably instantly deny and disparage, in the exact same way the climate-change deniers deny climate change science, using the exact same arguments climate-change deniers use. You personally might not, but it is very common among scientists to deny very well replicated science, using the same language, because, to use your language "it does not fit with their beliefs". I am talking about a large body of published research in respected journals here, not some conspiracy theory in case anyone thinks that. I've seen it all before. The majority of scientists are closed-minded, if masses of published hard science does not fit their worldview. Let's face it. A huge number of scientists denied global warming in the 1980s and attacked scientists who were saying it. It is STILL happening today. Look a the recent barrage of attacks, many from scientists, on Dr. James Hansen, who is just trying to wake people up.
(It should be obvious from my posts that I am for science . I studied the concept of greenhouse effects, in-depth, before that term even remotely entered the general lexicon applied to this planet, and was then hardly even used in the scientific community about Earth, except by a tiny number of scientists, if at all).

The Arctic is melting, the droughts are increasing worldwide as we speak.
But this is not the forum, thanks.
Tommy

« Last Edit: July 29, 2015, 02:22:37 PM by Tommy »

Nick_Naylor

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Re: The 2015 melting season
« Reply #2702 on: July 28, 2015, 09:50:55 PM »
SSTs at or near freezing have little impact on melt at this point in the season.  The heat already in the water and down-welling radiation will be hard at work through September.

OK, but if weather doesn't matter in August, why couldn't we have said the same at this time of year in 2013 or 2014? Is there a quantifiable difference in stored heat, or am I missing something?

12Patrick

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Re: The 2015 melting season
« Reply #2703 on: July 28, 2015, 09:57:23 PM »
As the dipole shifts more to the NW of Greenland this week I suspect more ice melt on Greenland to occur this week as warmer winds from more southern regions return over Greenland which will tend to warm it more... Lets keep an eye on it...
« Last Edit: July 28, 2015, 10:08:00 PM by 12Patrick »

weatherdude88

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Re: The 2015 melting season
« Reply #2704 on: July 28, 2015, 10:18:17 PM »
As the dipole shifts more to the NW of Greenland this week

I would suggest understanding the terminology you are using before posting.

Quote
The Arctic dipole anomaly is a pressure pattern characterized by high pressure on the arctic regions of North America, and a low pressure on the Eurasia region

https://en.wikipedia.org/wiki/Arctic_dipole_anomaly

« Last Edit: July 28, 2015, 10:25:23 PM by weatherdude88 »

12Patrick

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Re: The 2015 melting season
« Reply #2705 on: July 28, 2015, 10:36:44 PM »
As the dipole shifts more to the NW of Greenland this week

I would suggest understanding the terminology you are using before posting.

Quote
The Arctic dipole anomaly is a pressure pattern characterized by high pressure on the arctic regions of North America, and a low pressure on the Eurasia region

https://en.wikipedia.org/wiki/Arctic_dipole_anomaly

Yes I read about the dipole way back in 2007 and associate the dipole with the low pressure systems that form over or the near the North Pole... So when I say Dipole I really mean Low pressure system over the North Pole.. TYVM.

Neven

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Re: The 2015 melting season
« Reply #2706 on: July 28, 2015, 11:09:50 PM »
The second half of July has so far been exceptional when compared to the top years (2007, 2010, 2011 and 2012), let alone rebound years 2013 and 2014. 2007 had average high pressure over the Central Arctic, but this year pressure is so much higher and larger. Temps are similar to 2007, but look at that bull's eye in the CAA (below the SLP map):
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skanky

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Re: The 2015 melting season
« Reply #2707 on: July 28, 2015, 11:24:47 PM »
Being able to average all of the GFS or ECWMF predictions (as I can with NCEP/NCAR for past data) would be invaluable.


See Wetterzentrale's "Ensemblemittel" panels
http://www.wetterzentrale.de/topkarten/tkecmnh.html

Or Weather Online's Ensemble pages.





Andreas T

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Re: The 2015 melting season
« Reply #2708 on: July 28, 2015, 11:32:32 PM »
depends on how much ice dies on the European side. A lot of warm water appears to be driven under the ice from north atlantic and Barents. No need to export the ice if you can melt it out in situ.

And apart from this: I would not call the first week of August "End of the melt season".

plinius,

SST's in August average above -1.8 Celsius in the western and Siberian side of the arctic, so of course you will have melt throughout the month of August. (Water has a very high heat capacity and therefore will trump air temperatures) Additionally the wind profiles suggest ice transport from the eastern side to the Beaufort which is the mechanism that could increase extent in that region. Let's be realistic. If this pattern locks in place there will be a dramatic slowdown. SST's in the northern Atlantic are colder then the previous 5 melting seasons. So I fail to see how SST's from the northern Atlantic or Barents will have a significant effect.
Disagree; SSTs at or near freezing have little impact on melt at this point in the season.  The heat already in the water and down-welling radiation will be hard at work through September.
The (re-)attached graphs show downwelling shortwave and downwelling longwave radiation roughly balancing upwelling longwave in late summer This depends to some extent on weather but since good conditions for incoming sunlight are also poor conditions for downwelling longwave and shortwave gets pretty weak in September I can't see it doing a lot of "work" melting ice. By that time it is pretty much only bottom melt from sea water. The best radiation and air can do is limit heat loss from that water. This already applies to some extent to late August.

LRC1962

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Re: The 2015 melting season
« Reply #2709 on: July 28, 2015, 11:36:18 PM »
Scientists these days are displaying thinly disguised alarm.
We can avoid the worst of the coming changes if people wake up.
Can we really? There's nothing we can do to save the Arctic sea ice, which may mean that there's nothing we can do to prevent catastrophic climate change. The Arctic is one of the major systems contributing to global climate and weather. It's in the process of changing in a binary way from an icy to an ice-free state. The time for waking up was perhaps twenty years ago.
Using BAU as a base that is true. From an engineering stand point (and I am not talking about gassing the atmosphere to get things cool that is suicide) I refuse to believe it. Man built the great wonders of the world with much less technology then we have now and we can not repeat the builds because we can not imagine how to do it.
Get the right man with the right imagination and the right idea and anything IS possible. Fido + light bulb + need of 100 gigatonnes of ice in Arctic in 6 months = no problem. What we only lack right now is Fido and the light bulb. Granted we will have to repeat the venture until we get CO2 down to 280 ppm, but that is a separate engineering issue.
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Neven

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Re: The 2015 melting season
« Reply #2710 on: July 28, 2015, 11:40:18 PM »
Guys, there are I don't know how many threads on this Forum to ruminate and speculate about AGW in general, its consequences, the role of scientists in it, etc, etc.
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OldLeatherneck

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Re: The 2015 melting season
« Reply #2711 on: July 28, 2015, 11:48:25 PM »
Guys, there are I don't know how many threads on this Forum to ruminate and speculate about AGW in general, its consequences, the role of scientists in it, etc, etc.

Thanks Neven,

Between off topic discussions and new members just learning about Arctic Ice Loss I've gotten confused.  I've always depended on the analysis of some of the "OLD TIMERS" here to provide near-term forecasts for the upcoming weather in the Arctic regions.  After all of the noise in the discussions today, I don't know whether to expect a dramatic slow down in the melting or a continued rapid decline such as seen in 2007, 2011 or 2012.
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Neven

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Re: The 2015 melting season
« Reply #2712 on: July 28, 2015, 11:56:38 PM »
After all of the noise in the discussions today, I don't know whether to expect a dramatic slow down in the melting or a continued rapid decline such as seen in 2007, 2011 or 2012.

It's very much up in the air right now, OLN. At least, that's what I think. If there is a slowdown, though, I'm not sure it will be dramatic.

And forget about 2012. My jaw still hurts from that one.
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12Patrick

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Re: The 2015 melting season
« Reply #2713 on: July 28, 2015, 11:58:29 PM »
Scientists these days are displaying thinly disguised alarm.
We can avoid the worst of the coming changes if people wake up.
Can we really? There's nothing we can do to save the Arctic sea ice, which may mean that there's nothing we can do to prevent catastrophic climate change. The Arctic is one of the major systems contributing to global climate and weather. It's in the process of changing in a binary way from an icy to an ice-free state. The time for waking up was perhaps twenty years ago.
Using BAU as a base that is true. From an engineering stand point (and I am not talking about gassing the atmosphere to get things cool that is suicide) I refuse to believe it. Man built the great wonders of the world with much less technology then we have now and we can not repeat the builds because we can not imagine how to do it.
Get the right man with the right imagination and the right idea and anything IS possible. Fido + light bulb + need of 100 gigatonnes of ice in Arctic in 6 months = no problem. What we only lack right now is Fido and the light bulb. Granted we will have to repeat the venture until we get CO2 down to 280 ppm, but that is a separate engineering issue.
   LRC1962  I refer you see my tunnel idea in policy and solutions....

seaicesailor

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Re: The 2015 melting season
« Reply #2714 on: July 29, 2015, 12:26:51 AM »
Wont be ready before Sep.

 
SSTs at or near freezing have little impact on melt at this point in the season.  The heat already in the water and down-welling radiation will be hard at work through September.

OK, but if weather doesn't matter in August, why couldn't we have said the same at this time of year in 2013 or 2014? Is there a quantifiable difference in stored heat, or am I missing something?

SSTs do matter and anomalies are very high all around Arctic periphery. They take a few days of cold weather to go down to normal from these levels, moderating the otherwise much colder bites. A few days during a melting season in an eternity, I am learning.

SSTs at Pacific high lats are very high and that still can lash back into the Arctic.

And land STs at NH medium and high lats are well above average! That can hit in August too. Cyclonic weather may cause also warm land airmass entrainment into the Arctic (apart from what jdallen mentioned, cyclonic winds pulling up warmer deep waters)

The whole NH is warm! I can only refer you to the ASIG plots of land and ocean temps. No time to post images.

AGW is coming back with vengeance, unfortunately


Tommy

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Re: The 2015 melting season
« Reply #2715 on: July 29, 2015, 12:29:55 AM »
« Last Edit: July 29, 2015, 03:07:57 AM by Tommy »

Neven

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Re: The 2015 melting season
« Reply #2716 on: July 29, 2015, 12:39:01 AM »
A bit worrying?

Well, like they say in Monty Python and the Holy Grail: It's only a model.  ;)

Wait for PIOMAS.
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seaicesailor

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Re: The 2015 melting season
« Reply #2717 on: July 29, 2015, 12:46:42 AM »
Don't worry be happy?



From DMI too.
BTW anybody finds a sense on this plot?

Tommy

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Re: The 2015 melting season
« Reply #2718 on: July 29, 2015, 12:59:42 AM »
Quote
seaicesailor
Don't worry be happy?

I dunno, There's a lot of broken up fragments making up the outer edges of the 'extent'. It's kindof an optical illusion when one looks at 'extent' I think. If it's broken up any more than usual, then extent won't show that. But I could be wrong.
But that's why volume is more significant I think, and it's plummeting.
Tommy
« Last Edit: July 29, 2015, 01:51:49 AM by Tommy »

Tommy

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Re: The 2015 melting season
« Reply #2719 on: July 29, 2015, 01:12:46 AM »
What do people think about this?
Does this gap have a name?
I think it is going to appear more and more each year.
Might as well christen it.

Sea ice  thickness.
July 22-27 below.
http://polarportal.dk/en/havisen-i-arktis/nbsp/sea-ice-extent/

jai mitchell

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Re: The 2015 melting season
« Reply #2720 on: July 29, 2015, 02:18:06 AM »
What do people think about this?
Does this gap have a name?
I think it is going to appear more and more each year.
Might as well christen it.

Sea ice  thickness.
July 22-27 below.
http://polarportal.dk/en/havisen-i-arktis/nbsp/sea-ice-extent/

Northwest Divergence Zone (soon to be the new Northwest Passage)
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Nick_Naylor

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Re: The 2015 melting season
« Reply #2721 on: July 29, 2015, 02:47:27 AM »
JAWS: Just Another Warning Sign. Like Amity's Mayor, we'll ignore it.

wili

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Re: The 2015 melting season
« Reply #2722 on: July 29, 2015, 03:33:15 AM »
One Warm Line

"A force de chercher de bonnes raisons, on en trouve; on les dit; et après on y tient, non pas tant parce qu'elles sont bonnes que pour ne pas se démentir." Choderlos de Laclos "You struggle to come up with some valid reasons, then cling to them, not because they're good, but just to not back down."

jdallen

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Re: The 2015 melting season
« Reply #2723 on: July 29, 2015, 05:18:07 AM »
SSTs at or near freezing have little impact on melt at this point in the season.  The heat already in the water and down-welling radiation will be hard at work through September.

OK, but if weather doesn't matter in August, why couldn't we have said the same at this time of year in 2013 or 2014? Is there a quantifiable difference in stored heat, or am I missing something?

Reasonable challenge;  my response was to the idea of "massive" decrease in melt.  All else being equal, clear skies with near zero temps won't reduce melt all that much.   Cut back the sunlight, you'll loose the effect of a lot of the radiation, but still have downwelling radiation affecting the ice, which still can be considerable.

To inhibit the melt, you need to give the heat someplace else to "sink" to - best is clear skies and temps a couple degrees below freezing, at which point black body radiation out of the atmosphere will start to reduce the heat going into phase change.

Part of my reasoning here also might be seen with these:

Current:
http://polar.ncep.noaa.gov/sst/ophi/color_newdisp_sst_north_pole_stereo_ophi0.png

2013:
http://polar.ncep.noaa.gov/sst/ophi/archive/20130728/color_sst_NPS_ophi0.png

There's a lot more heat available, I think.  It won't stop if the air temperatures decline for a few days.
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S.Pansa

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Re: The 2015 melting season
« Reply #2724 on: July 29, 2015, 07:07:38 AM »
I asked the TOPAZ4 bot, what he thinks will happen. Here is what it came up with: first image today, second image 08/05.

Doesnt't look like a big slowdown. Will be interesting to see who will be right, the Weatherdude or the bot.  My bets are on The Dude, because The Dude abides ...

ChrisReynolds

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Re: The 2015 melting season
« Reply #2725 on: July 29, 2015, 07:56:52 AM »
Being able to average all of the GFS or ECWMF predictions (as I can with NCEP/NCAR for past data) would be invaluable.


See Wetterzentrale's "Ensemblemittel" panels
http://www.wetterzentrale.de/topkarten/tkecmnh.html

Or Weather Online's Ensemble pages.

Sorry, I should have been more clear, that is the median of the ensemble, I mean averaging the maps from current day to the last day forecast to give the average SLP pattern over the period.

ChrisReynolds

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Re: The 2015 melting season
« Reply #2726 on: July 29, 2015, 08:00:39 AM »
What do people think about this?
Does this gap have a name?
I think it is going to appear more and more each year.
Might as well christen it.

Sea ice  thickness.
July 22-27 below.
http://polarportal.dk/en/havisen-i-arktis/nbsp/sea-ice-extent/

Yes it is a coastal flaw lead. It is very common through the whole year and happens in that region when the Arctic Ocean is under high pressure (clockwise winds).

(I missed Jai's answer - never heard of that term)

oren

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Re: The 2015 melting season
« Reply #2727 on: July 29, 2015, 08:04:23 AM »
In simplistic terms the way I understand it, the main difference in weather between 2013 and 2015 is not so much in weather going forward, but in previous weather up until now and its imprint on the ocean and the ice.

On another matter, I'm looking at IJIS extent and CT area numbers of the last few days, and they scream a slowdown to me, gone are the century breaks etc.. On the other hand I'm looking at Wipneus's Arctic Basin graph and it shows we are still sticking with 2012 and diverging more and more from 2013/2014, no slowdown in sight. So which is it? I'm confusing myself.

https://sites.google.com/site/arctischepinguin/home/amsr2/grf/basin-area-multiprod.png

https://sites.google.com/site/arctischepinguin/home/amsr2/grf/basin-extent-multiprod.png

skanky

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Re: The 2015 melting season
« Reply #2728 on: July 29, 2015, 10:40:47 AM »
Being able to average all of the GFS or ECWMF predictions (as I can with NCEP/NCAR for past data) would be invaluable.


See Wetterzentrale's "Ensemblemittel" panels
http://www.wetterzentrale.de/topkarten/tkecmnh.html

Or Weather Online's Ensemble pages.

Sorry, I should have been more clear, that is the median of the ensemble, I mean averaging the maps from current day to the last day forecast to give the average SLP pattern over the period.

Sorry - I was surprised that you "weren't" aware of those charts. Should have realised that you were and I'd misunderstood.

nukefix

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plinius

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Re: The 2015 melting season
« Reply #2730 on: July 29, 2015, 11:35:54 AM »
Disagree; SSTs at or near freezing have little impact on melt at this point in the season.  The heat already in the water and down-welling radiation will be hard at work through September.

I strongly disagree with that - a ten meter layer of 10C water near instantly takes out 1m of ice. And we have those waters directly adjacent to the ice front. If the circulation drives those under the ice, you can just follow this up by watching the ice disappear on top within days.
http://imb.erdc.dren.mil/irid_data/2015E_thick.png

This one just got over a little spin-off of the West-Spitzbergen current in the second week of June. That's 20 cm or so within 2 days. And just a weaker version of what happens if you now advect warm water under the ice.

nukefix

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Re: The 2015 melting season
« Reply #2731 on: July 29, 2015, 11:53:16 AM »
Disagree; SSTs at or near freezing have little impact on melt at this point in the season.  The heat already in the water and down-welling radiation will be hard at work through September.

I strongly disagree with that - a ten meter layer of 10C water near instantly takes out 1m of ice.
Sure, but SST measures the top millimeter or so.

plinius

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Re: The 2015 melting season
« Reply #2732 on: July 29, 2015, 12:15:11 PM »
I hope you are aware of typical thickness of mixed layer. In particular if there is no freshwater lens, like on the atlantic side.

Lennart van der Linde

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Re: The 2015 melting season
« Reply #2734 on: July 29, 2015, 03:30:54 PM »
So we have just seen the IJIS drop consecutively for 4 days, do you think this is a sign of the changing weather?

Tommy

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Re: The 2015 melting season
« Reply #2735 on: July 29, 2015, 04:27:16 PM »
The Newbie strikes again !

Ok Folks, I think I am the first to officially say this :-)

This gap is the biggest on record for sea ice thickness in the Arctic, on this model.
You can quote me on that.  :)

So it's  “Tommy’s Gap”, unless someone else said it is the biggest gap.
That’s its official name as of now. :-)

I also think it is a dramatic indicator of huge Arctic summer-ice shrink over the next 2-3 years.
Other models may have a different size gap, but they show the same dramatic change.
And the Satellite images, back to 2012, show the gap clearly bigger this year, and longer, eastwards, way along that Canadian coast.

Sorry for a bunch of gifs below.
I have looked back to 2004 on this, and recorded all of them from 2007-2015.
For brevity of imagery here, I will post only 4 of the worst years for the gap, that I could see.

This year, that gap (for ice thickness) is the biggest on record, and remember, they all go from JUL 9-10 -> AUG 29 ... EXCEPT 2015, which only goes from June 8 to JULY 28, and it is bigger than any of the others ever get, or even become in a month from now.

I am only showing:
2015 on top (up to JULY 28)
2014 below that (up to AUG 29)
2011 below that (up to AUG 29)
2008 at the bottom (up to AUG 29)

I would put in 2012, because it is so famous, but the post only takes 4 attachments, and 2012 was not as big a gap as any of these.

They all pause for 4 seconds a the end.

http://satwagraphics.com/testing/2015_8_jun_jul-28.gif

http://satwagraphics.com/testing/2014_10_jul_aug-29.gif

http://satwagraphics.com/testing/2011_10_jul_aug-29.gif

http://satwagraphics.com/testing/2008_10_jul_aug-29.gif

Remember, the first one (2015) only goes to yesterday, JULY 28.
The rest of them end at AUG 29.

Maps from: http://polarportal.dk/en/havisen-i-arktis/nbsp/sea-ice-extent/
« Last Edit: July 29, 2015, 09:43:56 PM by Tommy »

Jim Hunt

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Re: The 2015 melting season
« Reply #2736 on: July 29, 2015, 04:31:11 PM »
O-Buoys 9 & 12 both seem to be close to melting out into choppy seas:

http://GreatWhiteCon.info/resources/arctic-sea-ice-images/summer-2015-images/#OBuoy9
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jdallen

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Re: The 2015 melting season
« Reply #2737 on: July 29, 2015, 05:18:10 PM »
depends on how much ice dies on the European side. A lot of warm water appears to be driven under the ice from north atlantic and Barents. No need to export the ice if you can melt it out in situ.

And apart from this: I would not call the first week of August "End of the melt season".

plinius,

SST's in August average above -1.8 Celsius in the western and Siberian side of the arctic, so of course you will have melt throughout the month of August. (Water has a very high heat capacity and therefore will trump air temperatures) Additionally the wind profiles suggest ice transport from the eastern side to the Beaufort which is the mechanism that could increase extent in that region. Let's be realistic. If this pattern locks in place there will be a dramatic slowdown. SST's in the northern Atlantic are colder then the previous 5 melting seasons. So I fail to see how SST's from the northern Atlantic or Barents will have a significant effect.
Disagree; SSTs at or near freezing have little impact on melt at this point in the season.  The heat already in the water and down-welling radiation will be hard at work through September.
The (re-)attached graphs show downwelling shortwave and downwelling longwave radiation roughly balancing upwelling longwave in late summer This depends to some extent on weather but since good conditions for incoming sunlight are also poor conditions for downwelling longwave and shortwave gets pretty weak in September I can't see it doing a lot of "work" melting ice. By that time it is pretty much only bottom melt from sea water. The best radiation and air can do is limit heat loss from that water. This already applies to some extent to late August.
Thank you, Andreas; you pretty much make my point. A modest decrease of a degree or so in SSTs won't significantly slow melt.
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plinius

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Re: The 2015 melting season
« Reply #2738 on: July 29, 2015, 05:59:33 PM »
Thank you, Andreas; you pretty much make my point. A modest decrease of a degree or so in SSTs won't significantly slow melt.

I'd prefer absence of misrepresentations. On the Atlantic side the boundary faces a difference of -->10K and not 1. Nobody really talked about slowing melt either. If the ice gets on top of that water layer, convection ensures rapid melt-out. Also, could you point us to how much or few one K in sea temperature will change the heat flux?

@Andreas: Thanks indeed. Is there a good explanation for the differences between the two derivations?

Nick_Naylor

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Re: The 2015 melting season
« Reply #2739 on: July 29, 2015, 06:09:23 PM »
Ceres shows August 2012 lost about 10 watts/m^2 less over the Arctic than did August 2013, which corresponds to about 0.1 meter of ice melt over the entire Arctic - proportionally more when it is applied to remaining ice cover, and especially if it's effect is concentrated in the weakened periphery.

http://neo.sci.gsfc.nasa.gov/servlet/RenderData?si=1571807&cs=rgb&format=SS.CSV&width=1440&height=720
http://neo.sci.gsfc.nasa.gov/servlet/RenderData?si=1550467&cs=rgb&format=SS.CSV&width=1440&height=720

I'm not sure that's actually trivial, but doesn't seem to be the whole story.
So what are the remaining variables, if we don't think radiative balance makes much difference?

It seems we have are looking at stored heat to melt the remaining ice.
Brainstorming an inventory of potential sources:

- Sea surface layer already in the Arctic. Whether this heat melts ice, is radiated to space or is lost by warm air advection or seawater export seems to depend on wind patterns.

- Seawater imported into the Arctic. Again this depends primarily on weather, as well as initial temperatures.

- Warm air advected from elsewhere. Depends on surface temperatures in the surrounding land masses as well as prevailing wind patterns.

I'm sure I'm missing some things :)

I don't think we know too much about weather for the next month. Do we know anything about the overall stored energy in any of these inventories as compared to prior years?

Edit: I should have provided a link to the web site that data came from:
http://neo.sci.gsfc.nasa.gov/view.php?datasetId=CERES_NETFLUX_M&year=2012

ChrisReynolds

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Re: The 2015 melting season
« Reply #2740 on: July 29, 2015, 06:31:28 PM »
Being able to average all of the GFS or ECWMF predictions (as I can with NCEP/NCAR for past data) would be invaluable.


See Wetterzentrale's "Ensemblemittel" panels
http://www.wetterzentrale.de/topkarten/tkecmnh.html

Or Weather Online's Ensemble pages.

Sorry, I should have been more clear, that is the median of the ensemble, I mean averaging the maps from current day to the last day forecast to give the average SLP pattern over the period.

Sorry - I was surprised that you "weren't" aware of those charts. Should have realised that you were and I'd misunderstood.

No worries Skanky, the fault is probably mine, I'm often tired in the evening and be less precise than I should be.

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Re: The 2015 melting season
« Reply #2741 on: July 29, 2015, 06:45:00 PM »
Nick,

Help me out here, but I thought that the CERES measurement uncertainty, especially in the less-covered arctic region, prevents such detailed comparisons?
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Nick_Naylor

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Re: The 2015 melting season
« Reply #2742 on: July 29, 2015, 06:55:41 PM »
You could be right. Is a 10 W/m^2 difference too small to be believed?

seaicesailor

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Re: The 2015 melting season
« Reply #2743 on: July 29, 2015, 07:04:00 PM »

Forecasts predict this persistent cyclone for 1 week more over Beaufort. RIP MYI.
Colder air temperatures over the whole Arctic region, except for the CAA.
No much more readable for me 8)

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Re: The 2015 melting season
« Reply #2744 on: July 29, 2015, 07:58:18 PM »
Thank you, Andreas; you pretty much make my point. A modest decrease of a degree or so in SSTs won't significantly slow melt.

I'd prefer absence of misrepresentations. On the Atlantic side the boundary faces a difference of -->10K and not 1. Nobody really talked about slowing melt either. If the ice gets on top of that water layer, convection ensures rapid melt-out. Also, could you point us to how much or few one K in sea temperature will change the heat flux?

@Andreas: Thanks indeed. Is there a good explanation for the differences between the two derivations?
Perhaps I confused things.  My modest decrease comment was regarding air temperature rather than sea temperature, and that over the pack, rather than outside of it.
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ChrisReynolds

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Re: The 2015 melting season
« Reply #2745 on: July 29, 2015, 08:13:28 PM »
Somebody (last year IIRC) came on here and got grief for suggesting that late in the season what favours melt is cloud. They were right, as I said at the time.

This is supported by the plots provided by Andreas. By August insolation (SWDN) is only about 120W/m^2, while LW is still near its summer peak at around 320W/m^2. Andreas, are those figures for clear sky or mixed conditions? (I suspect mixed, cloudy and clear, given the size of the LW flux)

As Blaine has pointed out on page 51, LW emission of a black body at 0degC is 315W/m^2.
http://www.spectralcalc.com/blackbody_calculator/blackbody.php
The IR albedo of wet ice is virtually zero, so it approximates a black body, ice belwo zero is also an effective absorber of IR (IR around the 10 micrometer (um) decade). The emission is around 10um for the surface, and not far off that for the boundary layer in summer. So the ice both wet and dry absorbs most of the IR that hits it.

That means that the CERES August average downwelling IR is largely offset by the emission from the ice. That still leaves non negligible visible light (SWDN). Under clear sky much of this is reflected due to the low angle of incidence, but under clouds scattering means a wider range of incident anges and greater net absorption.

However clouds would also increase downwelling LW, (for the lurkers and newbies; LW = longwave = infrared). In this sense the average given for CERES LWDN may not be very useful, this is why I asked Andreas what the conditions for those graphs are.

I can't off the top of my head say how much more clouds back radiate compared to clear sky, but as an example: I've just taken my IR thermometer and pointed it at a patch of clear sky (UK summer) it reads temperatures of about -35degC, then I aimed it at some low cloud and it read +5degC. As a aside, during very warm humid weather in June clear sky was +10degC, clouds +20degC IIRC. This isn't really giving temperature, but the IR thermometer reads infra red radiation and the forgoing does show what effective backradiators clouds are, and how leaving the Arctic aside, humid clear air can radiate massive amounts of IR. The 315W/m^2 for 0degC gives a rough context as to the levels of radiation involved.

So if we want to see continued very good losses of sea ice we need more cloud. If the high pressure persists with clear sky then radiation from the ice will become more dominant, until the sun sets and the whole region turns into a net emitter (into space).

Underside melt is a big issue, but how much of an issue is it away from the ice edge once net emission exceeds net absorption? I don't think it is a coincidence that after early August compactness ceases to fall, and levels until the minimum, after which compactness rises again with the growth of new ice.



My interpretation of this is that, as Blaine noted (page 51) regards my plot of insolation and volume delta, after about the first week of August radiative melt largely ceases across the pack, and the melt continues from the edge inwards.

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Re: The 2015 melting season
« Reply #2746 on: July 29, 2015, 08:32:22 PM »
That's a really interesting post Chris. I wonder though, what happens when we factor in the other implications of low pressure? Assuming wind and waves are kept to a minimum (which should happen provided the LP remains slack and shallow), air under an upper trough tends to be much colder, and not really much wetter provided the LP originates (or has resided for significant) in the Arctic. Arctic based lows are the most effective way of generating a pool of cold air that lasts a long while after the low has filled, they tend to come with low wind speeds and solid light precipitation (snow must still be good at this time of year?).

I question whether these sorts of lows are really the bad guy, the ones to worry about originated over the American or Eurasian continent, they are often deep, deepening, extremely moist, warm and contain a mixture of liquid and solid precipitation.

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Re: The 2015 melting season
« Reply #2747 on: July 29, 2015, 08:47:59 PM »
I also think it is a dramatic indicator of huge Arctic summer-ice shrink over the next 2-3 years.

Why?  What's your reasoning/model?

seaicesailor

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Re: The 2015 melting season
« Reply #2748 on: July 29, 2015, 08:57:12 PM »
Somebody (last year IIRC) came on here and got grief for suggesting that late in the season what favours melt is cloud. They were right, as I said at the time.

This is supported by the plots provided by Andreas. By August insolation (SWDN) is only about 120W/m^2, while LW is still near its summer peak at around 320W/m^2. Andreas, are those figures for clear sky or mixed conditions? (I suspect mixed, cloudy and clear, given the size of the LW flux)

As Blaine has pointed out on page 51, LW emission of a black body at 0degC is 315W/m^2.
http://www.spectralcalc.com/blackbody_calculator/blackbody.php
The IR albedo of wet ice is virtually zero, so it approximates a black body, ice belwo zero is also an effective absorber of IR (IR around the 10 micrometer (um) decade). The emission is around 10um for the surface, and not far off that for the boundary layer in summer. So the ice both wet and dry absorbs most of the IR that hits it.

That means that the CERES August average downwelling IR is largely offset by the emission from the ice. That still leaves non negligible visible light (SWDN). Under clear sky much of this is reflected due to the low angle of incidence, but under clouds scattering means a wider range of incident anges and greater net absorption.

However clouds would also increase downwelling LW, (for the lurkers and newbies; LW = longwave = infrared).

....

So if we want to see continued very good losses of sea ice we need more cloud. If the high pressure persists with clear sky then radiation from the ice will become more dominant, until the sun sets and the whole region turns into a net emitter (into space).

Types of clouds:
Very tall T-storm-like, they will block almost all sun radiation. The IR downwelling will be high (unless the cloud bottom is extremely cold)
Clouds that are not tall then there will be scattered sun radiation,..., and IR downwelling.
If clouds are high and thin, some sun radiation scattered, no IR downwelling.
Fog. It is a IR trap, and some sun radiation scattered.
Humid clean sky
Dry clean sky.
Probably some of this is not correct. Anyhow: I wonder what kind of clouds can be expected from a persistent weak cyclone such as the one affecting Beaufort as we speak? Or can we expect diffrerent types of lows too as Qantum suggests?

cesium62

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Re: The 2015 melting season
« Reply #2749 on: July 29, 2015, 08:59:49 PM »
Ceres shows August 2012 lost about 10 watts/m^2 less over the Arctic than did August 2013, which corresponds to about 0.1 meter of ice melt over the entire Arctic - proportionally more when it is applied to remaining ice cover, and especially if it's effect is concentrated in the weakened periphery.

http://neo.sci.gsfc.nasa.gov/servlet/RenderData?si=1571807&cs=rgb&format=SS.CSV&width=1440&height=720
http://neo.sci.gsfc.nasa.gov/servlet/RenderData?si=1550467&cs=rgb&format=SS.CSV&width=1440&height=720

I'm not sure that's actually trivial, but doesn't seem to be the whole story.
So what are the remaining variables, if we don't think radiative balance makes much difference?

It seems we have are looking at stored heat to melt the remaining ice.
Brainstorming an inventory of potential sources:

- Sea surface layer already in the Arctic. Whether this heat melts ice, is radiated to space or is lost by warm air advection or seawater export seems to depend on wind patterns.

- Seawater imported into the Arctic. Again this depends primarily on weather, as well as initial temperatures.

- Warm air advected from elsewhere. Depends on surface temperatures in the surrounding land masses as well as prevailing wind patterns.

I'm sure I'm missing some things :)

I don't think we know too much about weather for the next month. Do we know anything about the overall stored energy in any of these inventories as compared to prior years?

Edit: I should have provided a link to the web site that data came from:
http://neo.sci.gsfc.nasa.gov/view.php?datasetId=CERES_NETFLUX_M&year=2012

The story I heard was that in 2012 a very special weather condition, a large cyclone, swept through the arctic around August 4th and trashed things.  So I would think the inventory of potential sources would include:
-- scattered ice / lower concentration
-- broken ice / smaller floes
-- stirring of waters
-- waves blowing water up on ice
-- humidity? rain?
Or perhaps most of the above can be summarized as:
-- high winds