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Archimid

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Re: The 2018 melting season
« Reply #3000 on: August 22, 2018, 04:12:10 PM »
Judging by the N80 graph and the day to night ratio of the Arctic at this time of the year this thought occurs to me.  Around this time clouds start the transition from negative feedback to positive feedback.
I am an energy reservoir seemingly intent on lowering entropy for self preservation.

magnamentis

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Re: The 2018 melting season
« Reply #3001 on: August 22, 2018, 04:25:21 PM »
Is it strange that Northern greenland has water above it?

I always thought this was pure frozen ice with little chance of melt

it did not melt, it was driven away by winds and currents mostly due to the fact that due lack of thick stable ice-cover all around it as well provided much less resistance, at least IMO that explains the amount of open water in relation to wind speeds and periods.

Does this quote from A-team suggest that there is melt - not just movement?

Quote
The first animation, an overlay of OSI-SAF ice motion vectors on UH AMSR2 sea ice concentration, shows that this is not a lift-off event (overall icepack rotation or bulk movement) relative to north Greenland and the CAA coastline.

of course there is melt at this time of the year but melt and open water through "melt out" is not the same. melt out would mean in this case that where now is open water that all that ice has melted out while in fact, most of that open water was wind and current driven retreat and self-evidently seasonal melt continued simultaneously and perhaps some warming of the waters could have prevented refreeze as opposed to the february event when it re-froze quite quickly once the off-shore winds abated.

further i'm not a big friend of name and/or title-based reasoning, reasoning should be based on information and/or opinions based on as correct as possible information and meaningful convictions while the latter is already dangerous. Most manmade catastrophes were in big part based on blind followership, kind of fanboyism and hyping glorification, this is why i don't like that and all reasoning based on it.

only exception for me are names that are known for being honest and "ethically clean" those names i trust for good reason, while who knows one thing does not necessarily know another and who did a good job yesterday does not necessarily do the same tomorrow.

especially does technical know-how not say much about understanding that processed data, not even about their quality, even though i understand that such nice and colorful stuff pleases most eyes and is impressive.

or since when is a painter who knows how to portrait beautiful women automatically a good husband or lover LOL

this will put another dent into the wall LOL, so what, enjoy further
« Last Edit: August 22, 2018, 04:38:13 PM by magnamentis »

oren

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Re: The 2018 melting season
« Reply #3002 on: August 22, 2018, 05:21:52 PM »
Magna, no need for big names or to be a believer, just looking at the many animations posted in the last few days of the area north of Greenland, you can see the big floes not moving much, rotating, moving back and forth, but not moving a large distance in one direction, and during that time more and more open water is around and between them. Do you call that - wind-driven, current-driven, or strong melting?

Jim Hunt

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Re: The 2018 melting season
« Reply #3003 on: August 22, 2018, 05:22:36 PM »
Hardly anybody seems to have watched this video yet. However IMHO it's amazing, as indeed is Ann:



Quote
How cool is that?

Minus silly!

Reality is merely an illusion, albeit a very persistent one - Albert Einstein

Dharma Rupa

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Re: The 2018 melting season
« Reply #3004 on: August 22, 2018, 05:39:35 PM »
Judging by the N80 graph and the day to night ratio of the Arctic at this time of the year this thought occurs to me.  Around this time clouds start the transition from negative feedback to positive feedback.

Yup.

FishOutofWater

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Re: The 2018 melting season
« Reply #3005 on: August 22, 2018, 06:16:31 PM »
The DMI 80N shows that the polar melt season has gone into overtime. And it isn't solar radiation doing it because the sun angle is too low. It's warm, humid, cloudy air advecting from the open water where the Arctic ocean is "Atlantifying".

The climate denier video posted above in response to my comment was pernicious because it launched a duplicitous attack on science. There's no doubt that in areas of industry funded science that there's corruption of the scientific method (e.g. negative or harmful results found in drug studies) but the denier's suggestion that all of climate science is tainted by the funding process and group think is a vile lie. Evidence well displayed on blogs such as Skeptical Science and by Snow White here have demonstrated that it is the deniers who have been corrupted by the money of big oil, gas and coal.

Back on topic, there's a surprising amount of very thin, dispersed, mushy ice still being blown about by wind and storms over summer season warmed water. There's still the potential for a large amount of melt into mid September in this situation.

RoxTheGeologist

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Re: The 2018 melting season
« Reply #3006 on: August 22, 2018, 06:44:09 PM »

The DMI 80N shows that the polar melt season has gone into overtime. And it isn't solar radiation doing it because the sun angle is too low. It's warm, humid, cloudy air advecting from the open water where the Arctic ocean is "Atlantifying".


My thoughts are that the DMI 80N graph is relatively useless over the summer, it' doesn't show the extra energy that has been added to the Arctic - see the graph below - there is no increasing anomaly over the summer mean, only the winter mean. The energy is absorbed by melting ice, and the temperature hovers just above 0 °C. The anomalously low ice along the whole of the Atlantic front including the Laptev Sea will start become more obvious as the DMI 80N mean temperatures drop in the coming weeks.

Phil.

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Re: The 2018 melting season
« Reply #3007 on: August 22, 2018, 08:08:48 PM »

The DMI 80N shows that the polar melt season has gone into overtime. And it isn't solar radiation doing it because the sun angle is too low. It's warm, humid, cloudy air advecting from the open water where the Arctic ocean is "Atlantifying".


My thoughts are that the DMI 80N graph is relatively useless over the summer, it' doesn't show the extra energy that has been added to the Arctic - see the graph below - there is no increasing anomaly over the summer mean, only the winter mean. The energy is absorbed by melting ice, and the temperature hovers just above 0 °C. The anomalously low ice along the whole of the Atlantic front including the Laptev Sea will start become more obvious as the DMI 80N mean temperatures drop in the coming weeks.

The anomaly also increases during the spring and fall.

Phil.

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Re: The 2018 melting season
« Reply #3008 on: August 22, 2018, 08:30:30 PM »

Thanks Phil -


Maybe you would like to start a thread for their expedition progress and see how they get on in Dogbark! - I found:
http://arcticnorthwestpassage.blogspot.com/2018/08/northwest-passage-on-dogbark.html

They have now turned back due to a message received from the Canadian Coastguard.


From: “NordReg1 Iqaluit” <iqanordreg@innav.gc.ca>
Subject: 9H9573 – INFO – 08-18-1256 – LR – HEAVIER ICE CONDITIONS
Date: Sat, 18 Aug 2018 13:06:44 +0000
NORDREG IQALUIT 181256UTC AUG 2018

Good morning,
Due to heavier than normal ice concentrations in the Canadian arctic
waters north of 70 degrees, the Canadian Coast Guard, recommends that
pleasure craft do not navigate in the Beaufort Sea, Barrow, Peel Sound,
Franklin Strait and Prince Regent. CCG icebreakers cannot safely escort
pleasure craft. Operators of pleasure craft considering a northwest
passage should also consider the risk of having to winter in a safe
haven in the Arctic, or in the case of an emergency, be evacuated from
beset vessels. Safety of mariners is our primary concern.
REGARDS,
NORDREG CANADA
181256UTC\LR

Stephan

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Re: The 2018 melting season
« Reply #3009 on: August 22, 2018, 08:32:33 PM »
I'm going to do a no-no for this forum and link a video from what you would call a skeptic of sorts. It does have relevance to the TSI subject. It's only 6 minutes and if you can forget the source for a second- I would like to know what you think.  Is it hogwash or has any merit?
I'll understand if I'm banned for this :)

The speaker talks about facts, but he didn't bring any. It may be that an extra strong flash of solar outburst may have a small and short-lived influence on earth's temperature. But I completely miss the development of the changes in quantitative numbers over the last 140 years. I am no climate scientist so I can not judge whether the changes are around 0,1% as he complains about or bigger as he says they would be. We should let "potholer" analyse this video and ask real scientists like Rahmstorf, Mann, Beckwith or Hansen to evaluate the content.
For me this video is in line with all the other AGW denier videos, well-made but without any useable content.
« Last Edit: August 22, 2018, 08:39:20 PM by Stephan »
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Thomas Barlow

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Re: The 2018 melting season
« Reply #3010 on: August 22, 2018, 08:41:26 PM »
Ice over 4 metres thick is pretty much gone.
By mid-September, ice over 3 metres thick could be gone.
http://polarportal.dk/en/sea-ice-and-icebergs/sea-ice-thickness-and-volume/#c23629
« Last Edit: August 22, 2018, 09:23:38 PM by Thomas Barlow »

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Re: The 2018 melting season
« Reply #3011 on: August 22, 2018, 08:48:20 PM »
For comparison, here's 15 Sept. 2012.
I wonder what the thickness will look like this year at that time?
Or, if longer melt seasons could kick in this year, with the N. Atlantic still invading deeper into the Arctic Ocean later into September.

Stephan

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Re: The 2018 melting season
« Reply #3012 on: August 22, 2018, 08:49:19 PM »
(has already been mentioned by other members of this forum)
It is impressive how far north the ice edge is towards Barents and Kara Sea this year.
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marcel_g

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Re: The 2018 melting season
« Reply #3013 on: August 22, 2018, 08:51:53 PM »
I'm going to do a no-no for this forum and link a video from what you would call a skeptic of sorts. It does have relevance to the TSI subject. It's only 6 minutes and if you can forget the source for a second- I would like to know what you think.  Is it hogwash or has any merit?
I'll understand if I'm banned for this :)

The speaker talks about facts, but he didn't bring any. It may be that an extra strong flash of solar outburst may have a small and short-lived influence on earth's temperature. But I completely miss the development of the changes in quantitative numbers over the last 140 years. I am no climate scientist so I can not judge whether the changes are around 0,1% as he complains about or bigger as he says they would be. We should let "potholer" analyse this video and ask real scientists like Rahmstorf, Mann, Beckwith or Hansen to evaluate the content.
For me this video is in line with all the other AGW denier videos, well-made but without any useable content.

Don't waste anyone's time with this. It looks to me like a common troll tactic that I've heard of called "just asking questions" ( https://rationalwiki.org/wiki/Just_asking_questions ) , seems innocuous enough at first glance, but it's designed to take a discussion off the rails or, in this case, completely off topic.

marcel_g

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Re: The 2018 melting season
« Reply #3014 on: August 22, 2018, 08:58:09 PM »
Ice over 4 metres thick is pretty much gone.
By mid-September, ice over 3 metres thick could be gone.

Looks like this year has a lot more green and turquiose than those other years, and less of the purple and blue areas, which seem to represent the ice that will melt out before the end of melt season. So a less exciting melt season, but thankfully the ice seems to have dodged another bullet this year.

I looked at the wind forecast on climate reanalyzer, and it looks like there will be some windiness that will attack the ice in the Laptev and ESS, but maybe not sustained enough to cause enough dispersion to melt a lot of ice.

NeilT

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Re: The 2018 melting season
« Reply #3015 on: August 22, 2018, 09:57:47 PM »
We should let "potholer" analyse this video and ask real scientists like Rahmstorf, Mann, Beckwith or Hansen to evaluate the content.

Did anyone read the link I posted to RealClimate?  Mann and Hansen have already analysed the impact of solar (or the lack of it in this case), against GHG emissions.

The net result is: 

Yes, extreme solar minimum flare events reduce temperatures over a long time (0.3C by the century end)
No it doesn't really stop anything as the GHG trend over the same time is 4C, when not mitigated by any attempt to reduce emissions.

In very short.  YES solar fluctuation does have an impact.  NO, that impact is not significant, but it is there and it is measurable.
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Dharma Rupa

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Re: The 2018 melting season
« Reply #3016 on: August 22, 2018, 11:09:18 PM »
The DMI 80N shows that the polar melt season has gone into overtime. And it isn't solar radiation doing it because the sun angle is too low. It's warm, humid, cloudy air advecting from the open water where the Arctic ocean is "Atlantifying".

Let's not rush things, even if you are right.  At the moment we are watching to see if the pattern of the last two winters will continue.

There certainly those of us on the WACCy equable climate side who have expectations, but it isn't there yet.

jdallen

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Re: The 2018 melting season
« Reply #3017 on: August 22, 2018, 11:46:00 PM »
August 17-21.
Here's another Worldview, a little animation of the rotten ice field roughly north of Wrangel Island at 75+N. The animation covers Aug 10th-14th-21st with high resolution. The ice seems almost stationary, melting in-situ. The ice concentration and floe recognizability have gone down significantly. I can't imagine much of this ice field surviving the next 4 weeks in this southerly location until the expected refreeze in the middle of September.
CLICK to animate and ZOOM.
Earlier in the season, this is ice I would expect to disappear  completely in 10-14 days.  We will see if moment on carries it away, or if it is saved by the bell. So to speak.
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Brigantine

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Re: The 2018 melting season
« Reply #3018 on: August 23, 2018, 12:08:32 AM »
The garlic press is now open. Just half of one channel immediately west of Axel Heiberg.


johnm33

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Re: The 2018 melting season
« Reply #3019 on: August 23, 2018, 12:54:47 AM »
"The garlic press is now open. Just half of one channel immediately west of Axel Heiberg."
Just in time for the next tidal barrage of Atlantic water ingress, interesting times.

Michael Hauber

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Re: The 2018 melting season
« Reply #3020 on: August 23, 2018, 01:30:18 AM »

In very short.  YES solar fluctuation does have an impact.  NO, that impact is not significant, but it is there and it is measurable.

Bordering on overly pedantic quibbling over definitions, and hopefully not crossing the line: I'd say anything there and measurable is significant.  For instance Collins dictionary definition

Quote
A significant amount or effect is large enough to be important or affect a situation to a noticeable degree.

Perhaps it depends on context, if you are trying to carefully analyse climate and build a model of everything going on then solar input is big enough that it should be included in the model (and  has been in at least some that I know of), and is therefore significant.  If you want to explain what is currently happening with climate to a layman who doesn't want to get bogged down in all the details than solar influence is small enough to be ignored and so not significant.

edit:  And a big issue with solar is possible regional changes brought about by circulation changes.  For instance part of the little ice age issue is that the cooling was strongest in regions not far from the Arctic, tied into changes to Atlantic Oscillation that may be linked to solar activity.  Quick google search finds this paper.  It is possible that low solar activity may lead to reductions in sea ice due to regional cooling in Europe etc balanced partly by regional warming in Arctic.
« Last Edit: August 23, 2018, 01:36:35 AM by Michael Hauber »
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slow wing

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Re: The 2018 melting season
« Reply #3021 on: August 23, 2018, 05:22:37 AM »
U. Bremen's false colour ice concentration maps show a week's action in the Arctic basin, ending on the map just released, 2018-08-22...

slow wing

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Re: The 2018 melting season
« Reply #3022 on: August 23, 2018, 09:22:15 AM »
After a couple of weeks of relentless Southerly winds from a warm Laptev Sea, the edge of the ice pack here is a smoothly curving line with no structure from individual ice floes.

oren

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Re: The 2018 melting season
« Reply #3023 on: August 23, 2018, 09:39:34 AM »
After a couple of weeks of relentless Southerly winds from a warm Laptev Sea, the edge of the ice pack here is a smoothly curving line with no structure from individual ice floes.
I think this is partially an illusion of clouds.

Frivolousz21

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Re: The 2018 melting season
« Reply #3024 on: August 23, 2018, 10:51:57 AM »
The ESS will likely melt out completely or very close.

The models show a mostly cyclonic flow developing the next week.

This will really eat at the weakest ice from the Beaufort to ESS because warm enough air will being pulled in won't really allow the water to vent much heat.

With so much open water the warm water will get sloshed a lot helping mix up heat through the broken ice.

It's impossible to tell but the ESS and Chuckie regions could fall off enough for a top 5 finish.
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uniquorn

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Re: The 2018 melting season
« Reply #3025 on: August 23, 2018, 01:41:19 PM »
Today's ecmwf wave and temps from Windy

slow wing

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Re: The 2018 melting season
« Reply #3026 on: August 23, 2018, 01:43:38 PM »
I think this is partially an illusion of clouds.

The other 2 satellites show the same shape against different cloud backgrounds.

NeilT

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Re: The 2018 melting season
« Reply #3027 on: August 23, 2018, 01:58:47 PM »
It's impossible to tell but the ESS and Chuckie regions could fall off enough for a top 5 finish.

They'd have to for extent because the NSIDC chartic is showing a slowing trend which bumps out sideways every 2-3 days and is currently sitting right on top of 2015 for joint 5th place.  One more bump sideways and it will be in 6th place.

At the same time the UB maps are showing a strengthening of the CAB and also areas of the ESS which are not already so far gone that they are doomed are starting to firm up a bit.

Also DMI 80N has hit 0C.  If we look at the sheer area of open water above 80N, skewing that figure, it means that the covered areas are already well under 0C.

Yet, still, we are only one really good storm away from a top 2/3 position.  Such is the very weakened state of the CAB.
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NeilT

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Re: The 2018 melting season
« Reply #3028 on: August 23, 2018, 02:29:42 PM »
Bordering on overly pedantic quibbling over definitions, and hopefully not crossing the line: I'd say anything there and measurable is significant.  For instance Collins dictionary definition

I wouldn't say overly pedantic.  Just very specific.  I was talking in terms of easily measurable impact in the Arctic melting season.  Because it is not "significant" in that way, i.e. a sunny day v a cloudy day is far more significant than a solar low sunny day produces less energy than a solar max sunny day. I should have been more specific there.

The slight change in the waxing and waning of the solar cycle does have an impact, because it is felt all over the planet and, also, because it can be felt constantly in the cryosphere.

It is just that all the other noise means it is extremely difficult (or impossible), to measure the impact there.  Worse GHG's, on a decadal cadence, outweigh the cycling of the solar input.  To the point where it is possible that one low is as high in insolation as the previous cycles high.

A bit off topic but it is a factor.
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Dharma Rupa

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Re: The 2018 melting season
« Reply #3029 on: August 23, 2018, 02:53:45 PM »
Still a bit early to tell, but it sure looks to me like the red line is trying hard to follow the blue line instead of the green line.

binntho

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Re: The 2018 melting season
« Reply #3030 on: August 23, 2018, 03:19:34 PM »
Also DMI 80N has hit 0C.  If we look at the sheer area of open water above 80N, skewing that figure, it means that the covered areas are already well under 0C.

Well, according to TropicalTidBits most of the CAB north of 80 is above freezing, and the coldest spot (just north of 80 on the Canadian side) is only at -3 or so, far above what is needed for a re-freeze.

But the northernmost part of Greenland and Ellesmere Island do come closer to the -11 or so required to freeze sea water (as I understand it), although presumably no sea ice will form on land.

GFS 2 meter air temperature from 12:00 zulu today:

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mostly_lurking

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Re: The 2018 melting season
« Reply #3031 on: August 23, 2018, 03:57:10 PM »

But the northernmost part of Greenland and Ellesmere Island do come closer to the -11 or so required to freeze sea water (as I understand it), although presumably no sea ice will form on land.

GFS 2 meter air temperature from 12:00 zulu today:

-11 ?   I think that is way off. Around-2 is about right.

Dharma Rupa

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Re: The 2018 melting season
« Reply #3032 on: August 23, 2018, 04:01:46 PM »

But the northernmost part of Greenland and Ellesmere Island do come closer to the -11 or so required to freeze sea water (as I understand it), although presumably no sea ice will form on land.

GFS 2 meter air temperature from 12:00 zulu today:

-11 ?   I think that is way off. Around-2 is about right.

I think you two are talking about two different things, though I don't know if either one of you is exactly right.  One is talking about air temperature and the other about water temperature.

mostly_lurking

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Re: The 2018 melting season
« Reply #3033 on: August 23, 2018, 04:04:47 PM »
Ahh... I definitely misunderstood.  :P

Niall Dollard

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Re: The 2018 melting season
« Reply #3034 on: August 23, 2018, 05:01:12 PM »

Well, according to TropicalTidBits most of the CAB north of 80 is above freezing, and the coldest spot (just north of 80 on the Canadian side) is only at -3 or so, far above what is needed for a re-freeze.

But the northernmost part of Greenland and Ellesmere Island do come closer to the -11 or so required to freeze sea water (as I understand it), although presumably no sea ice will form on land.


Last year one of the first areas to show early freeze were the bays and inlets of Ellesmere. Frazil ice can form when it gets to -7 C and by early Sept last year Eureka had consistent temps in the region of -7 C to -10 C and ice was observed in Nansen Sound. That's what air temperatures you need to get freeze started and we are not at that stage yet.

There are many mountainous areas on Ellesmere Island and Tropical Tidbits or Nullschool will often show pinpoint areas which are down to -10 C, even in Summer. But these low temps are not present at the coastal points.

I better keep quiet now as I know the freezing thread has not started yet and this seems to be a sensitive topic at this time of year !  :)

binntho

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Re: The 2018 melting season
« Reply #3035 on: August 23, 2018, 05:38:07 PM »
I wouldn't actually be surprised if freezing had started. But the different temps that have been mentioned are confusing, and I'm no expert. As I understand it, freezing temperature of sea water is around -1.8 degrees (inlets and straits in the CAA are presumably less salty). But as the surface sea water cools down towards freezing point it starts to sink and the warmer underlying waters rise. So freezing doesn't actually start until the water column has been cooled down sufficiently for the surface waters to stop descending.

But the -11 degrees figure was from memory, and it is supposedly the temperature that experience tells is needed for ice-free sea water to freeze. I'm not actually able to find any good references but my own experience tells me (both from Denmark and from Iceland) that sea water doesn't begin to freeze until the temperature is significantly below zero, way below the freezing point of salt water. To the North-West of Iceland the sea surface is mostly cold water coming down from the Arctic, and temperatures in winter regularly drop down towards -10, but sea ice hardly ever forms. On the other hand, sometimes arctic ice floats down to reach the shores of Iceland, although that hasn't happened for some 20 years or more as far as I know.
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litesong

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Re: The 2018 melting season
« Reply #3036 on: August 23, 2018, 05:39:59 PM »
Still a bit early to tell, but it sure looks to me like the red line is trying hard to follow the blue line instead of the green line.
Updating a previous post:
The sun is less than 12arcdeg above the horizon at the North Pole (& decreasing by over one third arcdeg per day), almost 12 arcdegs LESS than at summer beginning. Great percentages of direct solar energy, which was being absorbed by the Arctic biosphere(for 24hours per day) while the sun was relatively high in the Arctic sky, is now skipping off Arctic land, sea & air, back into space. Rapidly increasing regions of the Arctic are falling into darkness for extending periods of time. The solar TSI, which is radiating at a sub-standard level, has been warming the Arctic for 3-4+ months, but down-wardly affecting Arctic summertime temperatures. With the decreasing amounts of direct solar energy, the effect of ever increasing amounts of global man-made, infra-red energy absorbing GHGs is no longer being masked, & its warming effects will show increasingly, as the Arctic approaches fall, winter & spring months.   

Darvince

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Re: The 2018 melting season
« Reply #3037 on: August 23, 2018, 05:51:47 PM »
I don't think freezing has started anywhere in the Arctic yet, except maybe some humans on voyages around its edges freezing their butts off.  :P ;D ::)



Has anyone else noticed this in the near-term forecast? It's at day 4 now, so getting more certain. After passing through Laptev there is a tendency on D6-D7 to greatly increase its size on all the models I could easily access (GFS, ECMWF, GEM, UKMET) to weaken and cover much of the western Arctic. I don't know what the effects of a weak low pressure are during the transition season are supposed to be.


Peter Ellis

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Re: The 2018 melting season
« Reply #3038 on: August 23, 2018, 06:03:13 PM »
But the -11 degrees figure was from memory, and it is supposedly the temperature that experience tells is needed for ice-free sea water to freeze. I'm not actually able to find any good references

By my recollection, it was first mentioned on this forum (or possibly the ASI blog) by Wayne Davidson, and was referring to his personal observations of what is necessary for ice formation on or around his home location, which IIRC is somewhere in the Canadian Arctic Archipelago.

It's not a strict physical constant.  In an system with no further heat input, then ice will form - eventually - whenever the air temperature has been below the freezing point of sea water for long enough.  However, if the air temperature is only 0.1 degrees below freezing, then the heat transfer is slow enough that it will take weeks for the ice to form. 

Of course, given that the temperature continues to drop during the autumn / winter transition, and that there may be ongoing heat input from ocean currents etc, this means that by the time ice starts to form, the actual air temperature is always substantially below freezing.  The precise details will vary massively from place to place.  Shallow seas will freeze quicker (and ice will appear earlier in the season, at relatively higher air temperatures), because there is less of a heat store.  Fast flowing water will freeze slower because there's a constant heat influx as warmer waters get brought into the cooling zone.

Where the -11 comes from is that in Wayne Davidson's home town, the conditions are such that in an average year, the temperature is roughly -11 degrees by the time the ice starts to form.  No more.  This forum shouldn't be treating it as a magic number.

gerontocrat

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Re: The 2018 melting season
« Reply #3039 on: August 23, 2018, 06:30:45 PM »
Sea ice minimum is on average in about 3 weeks time.

Do I recall correctly a recent remark from A-team to the effect that on any day of the year somewhere in the Arctic there will be freezing and somewhere else in the Arctic there will be melting..?

We are still in the melting season - 51k km2 area loss on the 22nd August.

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Jim Hunt

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Re: The 2018 melting season
« Reply #3040 on: August 23, 2018, 07:06:58 PM »
Where the -11 comes from is that in Wayne Davidson's home town, the conditions are such that in an average year, the temperature is roughly -11 degrees by the time the ice starts to form.  No more.  This forum shouldn't be treating it as a magic number.

Resolute is more of a "home research station" than a "home town":

http://www.frederickcooksociety.org/refraction.htm

Agreed re the "magic number".
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Niall Dollard

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Re: The 2018 melting season
« Reply #3041 on: August 23, 2018, 07:44:24 PM »
Re freezing start point I agree too with what Peter and Jim have said already.

As a practical example, I refer back to early Sept last year. The first pink (ie new sea ice) images were appearing on the Canadian Sea Ice maps on 6th Sept.

I posted images and a GIF of the thickening ice in the Nansen Sound.

https://forum.arctic-sea-ice.net/index.php/topic,2141.msg128168.html#msg128168

The mean temperature at Eureka for the week Sept 4th to Sept 11th was -8.8 C. That's probably the highest weekly mean to get it started.



NeilT

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Re: The 2018 melting season
« Reply #3042 on: August 23, 2018, 08:06:51 PM »
The point is that you don't need -11 temps to stop ice melting.  0C will do it quite nicely.

Mean 80N temps are now 0C.  Precipitation in those 0C areas is more likely to fall as snow.

We are now running into storms and thermal inertial of the warmed ocean for melting now.  Rather than the bigger impact of solar in the Arctic Day.
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Steven

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Re: The 2018 melting season
« Reply #3043 on: August 23, 2018, 09:18:10 PM »
But the -11 degrees figure was from memory, and it is supposedly the temperature that experience tells is needed for ice-free sea water to freeze.

That wasn't the case in September 2016.  There was widespread refreezing of the open water north of the East Siberian Sea in mid-September 2016, even though the air temperatures in that region were still well above -10°C.

10 September 2016 sea ice:  https://tinyurl.com/y8vbqgql
20 September 2016 sea ice:  https://tinyurl.com/yc2wrmgs
Air temperatures during that period (in Kelvin):  mean, animation


magnamentis

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Re: The 2018 melting season
« Reply #3044 on: August 23, 2018, 10:53:48 PM »
But the -11 degrees figure was from memory, and it is supposedly the temperature that experience tells is needed for ice-free sea water to freeze.

That wasn't the case in September 2016.  There was widespread refreezing of the open water north of the East Siberian Sea in mid-September 2016, even though the air temperatures in that region were still well above -10°C.

10 September 2016 sea ice:  https://tinyurl.com/y8vbqgql
20 September 2016 sea ice:  https://tinyurl.com/yc2wrmgs
Air temperatures during that period (in Kelvin):  mean, animation

while it's true what you're saying i'd add that it depends mostly on salinity and in parts of wave action and wind-chill(speed) at a given temperatures.

as usual there is probably more to it which a non-weatherman can't all know/remember so i just add this without further validation of which factor counts how much.

RoxTheGeologist

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Re: The 2018 melting season
« Reply #3045 on: August 24, 2018, 12:54:50 AM »
But the -11 degrees figure was from memory, and it is supposedly the temperature that experience tells is needed for ice-free sea water to freeze.

That wasn't the case in September 2016.  There was widespread refreezing of the open water north of the East Siberian Sea in mid-September 2016, even though the air temperatures in that region were still well above -10°C.

10 September 2016 sea ice:  https://tinyurl.com/y8vbqgql
20 September 2016 sea ice:  https://tinyurl.com/yc2wrmgs
Air temperatures during that period (in Kelvin):  mean, animation


My assumption was that you had to be very cold to get ice to form despite convective overturning The heat lost to the atmosphere has to be greater than the heat input by convection. Once the ice has formed, then the water that forms the ice becomes less saline, bouyant, and stays frozen, relying on conduction for heat transfer rather than convection. That means that its easier to form ice with no surface mixing (still conditions) and where the depth of convection is small (close to land)

Dharma Rupa

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Re: The 2018 melting season
« Reply #3046 on: August 24, 2018, 02:06:32 AM »
My assumption was that you had to be very cold to get ice to form despite convective overturning The heat lost to the atmosphere has to be greater than the heat input by convection. Once the ice has formed, then the water that forms the ice becomes less saline, bouyant, and stays frozen, relying on conduction for heat transfer rather than convection. That means that its easier to form ice with no surface mixing (still conditions) and where the depth of convection is small (close to land)

Nice to have someone here who thinks of ice as a rock; which it is.

litesong

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Re: The 2018 melting season
« Reply #3047 on: August 24, 2018, 05:26:15 AM »
I don't think freezing has started anywhere in the Arctic yet....
Hail fell in Layton, Utah, today. Bet hikers on some high cloudy northern mountains on Greenland & Ellesmere Is. ain't wearin' shorts & thin white T-shirts. 
« Last Edit: August 24, 2018, 05:39:24 AM by litesong »

slow wing

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Re: The 2018 melting season
« Reply #3048 on: August 24, 2018, 05:50:55 AM »
U. Bremen's false colour ice concentration maps show a week's action in the Arctic basin, ending on the map just released, 2018-08-23...

Aluminium

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Re: The 2018 melting season
« Reply #3049 on: August 24, 2018, 07:16:55 AM »
August 19-23.