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jdallen

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Re: The 2019 melting season
« Reply #4300 on: July 22, 2019, 08:09:39 AM »
  So what should we fear most .. a GAC or two , a dipole to die for , or this glorious High dominating the Arctic for a week circumnavigated by the weakest of lows ?
Dipole of Doom, m'thinks.
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sark

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Re: The 2019 melting season
« Reply #4301 on: July 22, 2019, 08:29:32 AM »
It's not really a dipole so much as a quadrupole and a bipole.  think about it, bipolar cell.  since may day.  this was all written in advance by some comedians
I am not a scientist

ajouis

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Re: The 2019 melting season
« Reply #4302 on: July 22, 2019, 09:36:30 AM »
The piomas data seems to confirm what i was saying, that 2019 melt momentum is overcoming 2012. However, upon further inspection of the smos data, 2012 has a renewed melt momentum from the end of july to the first third of august, probably linked to the gac. We will see if the forecasted high pressure will manage to keep a similar momentum in high latitudes through as late a date. It will anyways increase the energy in the arctic system which will lengthen the melting season, and this might mean an even later refreeze than 2012, not good.
« Last Edit: July 22, 2019, 09:46:51 AM by ajouis »

Yuha

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Re: The 2019 melting season
« Reply #4303 on: July 22, 2019, 09:51:17 AM »
As long as sun is still high, sunshine is the worst for the ice in the long term, but the full effect is not immediate. A lot of the insolation goes through the ice and warms up the water below, and some of that heat may remain stored there for weeks. This is the heat that drives bottom melt in late melt season and provides most of the melting power of storms. Thus storms are most effective in melting the ice when they follow a long period of sunny weather.

Capt Kiwi

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Re: The 2019 melting season
« Reply #4304 on: July 22, 2019, 11:11:48 AM »
2. Aerosols are an issue, but you are over-stating it by a good order of magnitude. Effect is smaller than originally thought and far less abrupt.
 


Would you be able to point to that research please Killian? (I need some good news  :))

oren

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Re: The 2019 melting season
« Reply #4305 on: July 22, 2019, 11:30:16 AM »
Best to post such research in "the science of aerosols".

uniquorn

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Re: The 2019 melting season
« Reply #4306 on: July 22, 2019, 12:50:17 PM »
First semi-clear view on the ice in the ESS in a good week or so.
Looking for reasons for the low concentration area in the ess, nw of wrangel island prompted an overlay of yesterday's amsr2-uhh and noaa bathymetry.
This also highlights how far open water is developing over deep ocean. Notably in the beaufort but possibly also north of laptev.

Rich

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Re: The 2019 melting season
« Reply #4307 on: July 22, 2019, 12:55:36 PM »
So many cyclones, the Arctic is starting to look like Van Gogh's "Starry Starry Nights".

We now have a cyclone with 30 knot max winds covering most of the Archipelago.

While we fret over the weather to come in a few days, there is plenty of fascinating stuff going on in the moment.

uniquorn

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Re: The 2019 melting season
« Reply #4308 on: July 22, 2019, 01:19:53 PM »
Perhaps more of a worry is that the low concentration area is at the tip of the atlantic current, here shown using mercator salinity at 34m. Note also the lower concentration area above the current further west.
edit: forgot scale
« Last Edit: July 22, 2019, 01:38:03 PM by uniquorn »

subgeometer

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Re: The 2019 melting season
« Reply #4309 on: July 22, 2019, 01:29:36 PM »
Perhaps more of a worry is that the low concentration area is at the tip of the atlantic current, here shown using mercator salinity at 34m. Note also the lower concentration area above the current further west.

The match if Pacific salinity with melting patterns in the Chukchi Sea etc is also pretty neat - you can even see the baby elephants trunk along the Chukotka coast

Tom_Mazanec

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Re: The 2019 melting season
« Reply #4310 on: July 22, 2019, 01:54:26 PM »
Maybe it would be "better" (for some definition of better) for a BOE to occur next year, at the height of the POTUS election campaign.
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S.Pansa

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Re: The 2019 melting season
« Reply #4311 on: July 22, 2019, 02:16:57 PM »
@ Uniquorn, thanks for another set of stunning animations!

For those who wonder like me what the effects of the forcasted high could be: a few pics.
Nullschool & ESRL experimental forecast for the 26th, Topaz4, ice thickness changes from 22nd to 29th.

Warm temps, relative strong winds, strong melt from the top, bottom and the sides for the hole Pacific front - or in short: crunch time.
 
As the high is predicted to sit exactly where Piomas has the thickest ice, I wouldn't be surprised if 2019-volume continues to lead the field, perhaps even open the gap further to 2012.
Starting August with just below 6.000 km³? That would give 2019 a real shot at a new record low volume. Geez, now I am on the hype train too ::)
 
 
« Last Edit: July 22, 2019, 02:51:23 PM by S.Pansa »

Killian

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Re: The 2019 melting season
« Reply #4312 on: July 22, 2019, 02:40:56 PM »
As the high is predicted to sit exactly ...I wouldn't be surprised if 2019 continues to lead the field, perhaps even open the gap further to 2012.

Over what days? Over the next few, almost certain. After the 25th, much less certain as there is a 300k drop immediately. However, then it moderates a lot before diving 1M+ from 8/2 to 8/10.

If '19 is below '12 on 8/10, '12 is going to be looking over its shoulder.

All extent. Given area and volume are far more important, and '19 was leading in both last I looked, well, I'm going to be a bit shocked if '19 doesn't lead in one of the three if it leads in any after 8/10. Or, hell, at all.
« Last Edit: July 23, 2019, 03:44:20 AM by Killian »

S.Pansa

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Re: The 2019 melting season
« Reply #4313 on: July 22, 2019, 02:50:03 PM »
As the high is predicted to sit exactly ...I wouldn't be surprised if 2019 continues to lead the field, perhaps even open the gap further to 2012.

Over what days? Over the next few, almost certain. After the 25th, much less certain as there is a 300k drop immediately. However, then it moderates a lot before diving 1M+ from 8/2 to 8/10.

If '19 is below '12 on 8/10, '12 is going to be looking over its shoulder.

All extent. Given area and volume are far more important, and '19 was leading in both last I looked, well, I'm going to be a bit shocked if '19 doesn't lead in one of the three if it leads in any after 8/10. Or, hell, at all.



I was actually talking about volume. I guess I wasn't very clear, modified my post. Extent is a different story, also depending on the dataset we are looking. Wipneus homebrew is far out in front, others are much closer.

All this guesswork is tempting, but actually has little value me thinks. So I really shouldn't have fallen into this trap. I'll stop, I promise ;D  We now for certain in about 2 months

F.Tnioli

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Re: The 2019 melting season
« Reply #4314 on: July 22, 2019, 02:53:34 PM »
As long as sun is still high, sunshine is the worst for the ice in the long term, but the full effect is not immediate. A lot of the insolation goes through the ice and warms up the water below, and some of that heat may remain stored there for weeks. This is the heat that drives bottom melt in late melt season and provides most of the melting power of storms. Thus storms are most effective in melting the ice when they follow a long period of sunny weather.
All correct in principle, but i'd say you underestimate that heat, still, a bit. I'd rather say that the heat _will_ remain stored in the water column - more precisely, signicant portion of it surely will. There is no "may" about it, always happens when significant portion of sunlight gets absorbed dozens meters below surface (which is - always except highly non-transparent near-surface waters). And much of it will be stored for _months_, not just weeks. Affects freezing season, too.

uniquorn

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Re: The 2019 melting season
« Reply #4315 on: July 22, 2019, 03:15:26 PM »
The match if Pacific salinity with melting patterns in the Chukchi Sea etc is also pretty neat - you can even see the baby elephants trunk along the Chukotka coast
I need a better resolution bathymetry map. The noaa map doesn't have the ~30m trough west of wrangel shown on mercator. Does anyone have one? Complete arctic ocean.
edit: please post in maps thread here https://forum.arctic-sea-ice.net/index.php/topic,417.0.html
« Last Edit: July 22, 2019, 04:17:14 PM by uniquorn »

FishOutofWater

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Re: The 2019 melting season
« Reply #4316 on: July 22, 2019, 04:08:56 PM »
Mercator doesn't show evidence of much heat in that saline 30m water. The salinity, alone, will impact melting, however. Thanks for the outstanding animations, Uniquorn. That observable information shows that the Mercator model is pretty damn good in that region despite the paucity of data. Mercator's color gradients are not subtle enough to help us track Atlantic water heat that's possibly contributing in melting the ice.

In 2012 waters were warmer in late July on the Atlantic side but cooler on the Pacific side. Warm air advection into the Arctic from air masses originating from above these above normal temperature waters may play a major role in the late summer melting season. The forecast dipole pattern will import anomalously warm humid air from the Pacific.

Note that the cold water pool that was located southeast of Greenland for several recent years is gone, replaced by warm salty Gulf Stream water. The thermohaline circulation has recovered from the effects of the big Greenland melt years of 2010 and 2012.

« Last Edit: July 22, 2019, 04:40:09 PM by FishOutofWater »

uniquorn

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Re: The 2019 melting season
« Reply #4317 on: July 22, 2019, 04:21:52 PM »
Mercator doesn't show evidence of much heat in that saline 30m water
No, I wouldn't expect it to show, especially as it's a model. I tend to think that where the salinity goes, a little extra heat probably tags along with it.
Anyway it may just be coincidence. The next few days may tell us more.

TeaPotty

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Re: The 2019 melting season
« Reply #4318 on: July 22, 2019, 05:13:29 PM »

gerontocrat

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Re: The 2019 melting season
« Reply #4319 on: July 22, 2019, 05:21:40 PM »
The match if Pacific salinity with melting patterns in the Chukchi Sea etc is also pretty neat - you can even see the baby elephants trunk along the Chukotka coast
I need a better resolution bathymetry map. The noaa map doesn't have the ~30m trough west of wrangel shown on mercator. Does anyone have one? Complete arctic ocean.
edit: please post in maps thread here https://forum.arctic-sea-ice.net/index.php/topic,417.0.html
Posted 2 maps - I bet neither will do

And one more for luck in a couple of minutes
« Last Edit: July 22, 2019, 05:32:28 PM by gerontocrat »
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ColdMiser123

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Re: The 2019 melting season
« Reply #4320 on: July 22, 2019, 05:36:42 PM »
Pretty impressive that we are seeing ~100K losses still even with a more -DA pattern. Losses should only accelerate for at least the next ten days or so as we transition to a very hostile pattern for ice retention. The losses we saw in early 2012 were pretty impressive, but this upcoming pattern is one that at the very least should keep 2019 competitive with 2012.

Freegrass

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Re: The 2019 melting season
« Reply #4321 on: July 22, 2019, 05:36:47 PM »
It looks like that GAC I predicted turned into an entirely different beast. (First Image)
Can anyone tell me where the Jet stream went? All I can see is a picasso of a crazy sad face (Figure 2)
I find it fascinating how the wind goes through the Nares strait. Is that strait kinda like a ravine?
« Last Edit: July 22, 2019, 05:47:37 PM by Freegrass »
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be cause

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Re: The 2019 melting season
« Reply #4322 on: July 22, 2019, 05:42:11 PM »
prediction .. as Killian is proving on a daily basis is .. is not as easy as it seems .. b.c.
2007 + 5 = 2012 + 4 = 2016 + 3 = 2019 ...

Freegrass

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Re: The 2019 melting season
« Reply #4323 on: July 22, 2019, 05:57:35 PM »
prediction ... not as easy as it seems .. b.c.
Not on a day to day basis, but on a long term basis, we're all seeing where this is going...
So let me correct you if I may; "Prediction; We're all doomed!" Maybe not in "OUR" lifetime, but doomed for sure in the long run...

So let's stop trying to prove we were right with our predictions, and keep Neven's father in mind; In the end, we're all going back to where we came from... Same for the planet, but in different timescales...

Just be happy you have the brains to see the car wreck coming!

OH WAIT... Ignorance is bliss...
Now what?
« Last Edit: July 22, 2019, 10:52:44 PM by Freegrass »
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Freegrass

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Re: The 2019 melting season
« Reply #4324 on: July 22, 2019, 06:05:36 PM »
prediction .. as Killian is proving on a daily basis is .. is not as easy as it seems .. b.c.

Oh no you didn't just say that with your post 666, did you?
Joke lang! ;)
« Last Edit: July 22, 2019, 06:31:21 PM by Freegrass »
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philopek

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Re: The 2019 melting season
« Reply #4325 on: July 22, 2019, 06:15:53 PM »
As the high is predicted to sit exactly ...I wouldn't be surprised if 2019 continues to lead the field, perhaps even open the gap further to 2012.

Over what days? Over the next few, almost certain. After the 25th, much less certain as there is a 300k drop immediately. However, then it moderates a lot before diving 1M+ from 8/2 to 8/10.

If '19 is below '12 on 8/10, '12 is going to be looking over its shoulder.

All extent. Given area and volume are far more important, and '19 was leading in both last I looked, well, I'm going to be a bit shocked if '19 doesn't lead in one of the three if it leads in any after 8/10. Or, hell, at all.


 
Starting August with just below 6.000 km³? That would give 2019 a real shot at a new record low volume. Geez, now I am on the hype train too ::)
[/quote]

Beside what you already said, i strongly expect one or two drops in the vicinity of a triple-century-drop. Looking at the ice right now there will/must be some kind of sudden death in one or another corner of the arctic.

Should what i see coming happen, perhaps even simultaneously in more than one area, we could even see new record daily drops.

Greenbelt

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Re: The 2019 melting season
« Reply #4326 on: July 22, 2019, 07:26:04 PM »
To my untrained eyes, the forecast of a big dipole event this coming weekend now seems highly likely, with GFS now very similar to other models and solid ensemble support, with 1030mb high ranging from Fram to Beaufort and 1000mb low along the Siberian coast.  This is 12z today GFS operational for 0z Saturday. I just hope this weather pattern doesn't last too long -- at longer, more uncertain time ranges, the models are still showing a lot of 1020mb high pressure ideas in various locations within the central basin.


Sterks

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Re: The 2019 melting season
« Reply #4327 on: July 22, 2019, 08:01:21 PM »
Now GFS dipole on par with ECMWF.
I wonder if the strength of the ridge in some forecasts has anything to do with being better or worse aligned with that Scandinavian heat bomb

Rich

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Re: The 2019 melting season
« Reply #4328 on: July 22, 2019, 08:28:18 PM »
I'm not yet sold on the hype of the upcoming weather forecast.

GFS max 2m temps for the next 10 days are 2-3C where most of the ice is located. Average temps are obviously lower. Enough to keep melt going steadily, but nothing epic as far as I can tell.

grixm

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Re: The 2019 melting season
« Reply #4329 on: July 22, 2019, 09:00:57 PM »
GFS max 2m temps for the next 10 days are 2-3C where most of the ice is located. Average temps are obviously lower. Enough to keep melt going steadily, but nothing epic as far as I can tell.

Wouldn't the ice peg the surface temperature to around that level regardless of how much melt is going on? Since melting ice absorbs heat energy from the surroundings. I think something like 850hpa temps are more indicative of the actual stress the ice experiences.

oren

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Re: The 2019 melting season
« Reply #4330 on: July 22, 2019, 09:15:54 PM »
In the Arctic Basin, while NSIDC area slowed down enough to match 2012, JAXA and especially UH area continue sliding, taking 2019 to very uncharted territory. 2012's GAC looms large on the horizon, and 2016's GAC appears later. These are the only real contenders against 2019, with a 2nd place finish the more probable outcome.
I remind the forum of my prediction for an August GAC based on the accumulated High Arctic Albedo Warming Potential. If it comes, a new record will be quite easy. If it doesn't, a new record low for my (dubious) reputation...

Sterks

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Re: The 2019 melting season
« Reply #4331 on: July 22, 2019, 09:20:55 PM »
I'm not yet sold on the hype of the upcoming weather forecast.

GFS max 2m temps for the next 10 days are 2-3C where most of the ice is located. Average temps are obviously lower. Enough to keep melt going steadily, but nothing epic as far as I can tell.
2-3 C, 2m over the ice is really warm. Means there's a significant temperature gradient above the ice and thus heat transfer from the air to the ice
Anyway this event may be pretty short-lived, according to the latest EC, one week from now it is over.
« Last Edit: July 22, 2019, 09:25:56 PM by Sterks »

DrTskoul

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Re: The 2019 melting season
« Reply #4332 on: July 22, 2019, 09:36:29 PM »
One week here, one week there , and the damage accumulates..

RoxTheGeologist

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Re: The 2019 melting season
« Reply #4333 on: July 22, 2019, 09:43:09 PM »
The thing I find remarkable about the upcoming weather (climate reanalyzer) is that there is some snow forecast, but it is going to be over the largely open water on the Siberian side of the Arctic. Precipitation over the central basin is low or predicted to be rain. I think that is the other reason why cyclones slow down melt, other than clouds; fresh, high albedo snow. !0 day cumulative precipitation below:

UCMiami

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Re: The 2019 melting season
« Reply #4334 on: July 22, 2019, 09:44:29 PM »
Sterks - good point. We tend to think of air temp as an absolute in and of itself not recognizing how much it is effected by the surface over which it passes be it land, water, or ice. In the same way that we see SST as an absolute value, not recognizing the effect the ice floating on it changes the recorded values. The anomaly charts for SST early in the season showed a very strong Beaufort plus anomaly that has since changed to a very strong negative when the early loss of surface ice was replaced with large broken flows exported from the CAB.

That same dynamic leads to much colder 2M air temperature readings over the ice pack and keeps the 80N temperature chart midsummer barely above 0C year after year regardless of the larger weather patterns or the condition of the ice pack.

Ravenken

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Re: The 2019 melting season
« Reply #4335 on: July 22, 2019, 10:05:04 PM »
Perhaps more of a worry is that the low concentration area is at the tip of the atlantic current, here shown using mercator salinity at 34m. Note also the lower concentration area above the current further west.
edit: forgot scale

Question - any idea what might happen if these currents meet up? Anything special/unusual?
I am more ears than mouth.

werther

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Re: The 2019 melting season
« Reply #4336 on: July 22, 2019, 10:46:10 PM »
For the first time in years I checked 500 MB Geopotential height on NCEP-NCAR Daily Composites.

Because I guess I see unfolding what I was prepared to see for some years. This might become the season predicted, a very low extent/area minimum and a long, lingering slow refreeze. then some years of on/off seemingly stabilization. Followed by the feared state change in the Arctic.

The GH anomaly is, in a way, stronger than during may-july '12. Then, it was concentrated over southern Greenland, creating a strong flush-out dipole directed to Fram Strait. Now, the bulge on the mid-troposphere is strong over the Pole.

Coincides with the diagrams FishOutOfWater presented.
Strong influx of heat. Loss of Polar Cell characteristics.

And golfball-like hail in the Netherlands. And a probable all time heat record over here next Thursday.

I don't like to be a pessimist. I'll try to face what's coming with compassion.

Pretty Old Testament, isn't it?
« Last Edit: July 22, 2019, 11:02:32 PM by werther »

pauldry600

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Re: The 2019 melting season
« Reply #4337 on: July 22, 2019, 10:49:26 PM »
Even if min finishes below 4m on JAXA thats a major worry for me. I hvnt seen a global year with so little prolonged cold weather ever. There are certain cold spots but Baked Alaska and Roast Greenland are not two of them.

Greenland and the Antarctic were the two reasons I thought the weather models that showed a redder world in the future might be exagerrating it. But go back to those global predictions of the future and they are spot on.

Zero sea ice is no longer a case of if but when

Rich

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Re: The 2019 melting season
« Reply #4338 on: July 22, 2019, 10:53:21 PM »
I'm not yet sold on the hype of the upcoming weather forecast.

GFS max 2m temps for the next 10 days are 2-3C where most of the ice is located. Average temps are obviously lower. Enough to keep melt going steadily, but nothing epic as far as I can tell.
2-3 C, 2m over the ice is really warm. Means there's a significant temperature gradient above the ice and thus heat transfer from the air to the ice
Anyway this event may be pretty short-lived, according to the latest EC, one week from now it is over.

Let's keep in mind that 2-3C is the max, not the average for the 10 day forecast period.

I'm not the seasoned veteran here so I'll defer to the more experienced here. My limited experience of this year is that all of the periods of rapid in situ melt (as opposed to export) have been accompanied by higher 2m temps than those currently forecast.

It will certainly be an interesting learning experience to observe rapid in situ melt with mild air temps.

The cool thing about being new to this is learning a lot.

werther

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Re: The 2019 melting season
« Reply #4339 on: July 22, 2019, 11:00:24 PM »
Yes, Rich...
 
But very likely the damage has been done well before this week. What happens in the next few weeks will probably not change much in the final outcome at Minimum. nor during "refreeze".

I have watched enough MODIS tiles during 2010-2015 to see on Worldview the state of the ice is deplorable everywhere. Even in the former "safe-haven" 1,5 Mkm2 North of the CAA/Greenland.

jdallen

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Re: The 2019 melting season
« Reply #4340 on: July 22, 2019, 11:03:16 PM »
I'm not yet sold on the hype of the upcoming weather forecast.
2-3 C, 2m over the ice is really warm. Means there's a significant temperature gradient above the ice and thus heat transfer from the air to the ice<snip>
Let's keep in mind that 2-3C is the max, not the average for the 10 day forecast period.
There's a lot more than just air temperature in play here.  Wind will prompt movement and retrieval of heat from depth to the surface.  Wave action will have a mechanical effect on the ice.  Ice could be exported to peripheral regions with much higher SST's than where it sits currently.

The weather is striking the pack with a heated hammer; what remains is where, how hard, and where do the chips fly.


Quote
The cool thing about being new to this is learning a lot.

Good!

(Edit:  And echoing werther, much of the damage has already been done.)
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Pragma

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Re: The 2019 melting season
« Reply #4341 on: July 22, 2019, 11:10:51 PM »
It will certainly be an interesting learning experience to observe rapid in situ melt with mild air temps.

The cool thing about being new to this is learning a lot.

It's not just the air temperature, but the heat capacity of the air and the movement.

In still air, a boundary layer forms which is the same temperature as the ice, and no heat transfer happens.

If there is air movement, the boundary layer is stripped off and the new, warmer air will transfer it's heat to the ice.

The humidity will also greatly affect the heat capacity of the air.

So, an 8 deg dry atmosphere with no wind will melt far less ice than a 3 deg 30% RH air mass moving at 20 km/hr.

Thirdly, the higher the dew point, the more energy there is to be released in the form of condensation.

Temperature is just a part of the equation.

bluice

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Re: The 2019 melting season
« Reply #4342 on: July 22, 2019, 11:15:28 PM »
I would humbly suggest to have the learning part done in the Stupid Questions thread. Let’s not flood this discussion.
In PIOMAS we trust

werther

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Re: The 2019 melting season
« Reply #4343 on: July 22, 2019, 11:15:37 PM »




These are the GH anomalies I compared...

Viggy

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Re: The 2019 melting season
« Reply #4344 on: July 22, 2019, 11:21:56 PM »
Looking at the AMSR2 data coming in for today on NASA Worldview, sea ice in Chukchi and Laptev got absolutely decimated today. Kara and what's remaining of Hudson taking some good losses too.

Eye test tells me we are looking at a high 100k (maybe 200k) drop in extent today.

werther

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Re: The 2019 melting season
« Reply #4345 on: July 22, 2019, 11:26:00 PM »
Speaking of the Daily Composites...
Check the Arctic temp anomalies on 925Mb. Not on 2 meter, like DMI projects. That is much influenced by the melting drain of heat. Some couple of hundred meters higher the influx really shows.

Four degrees anomaly mean over three months is a lot.

Over almost the complete Central Arctic...

aslan

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Re: The 2019 melting season
« Reply #4346 on: July 22, 2019, 11:42:33 PM »
I will update the analysis when June 2019 data from MERRA will be available in late July -when nobody will no longer care as sea ice extent will be many thousands squared kilometers below 2012 and the crash will be beyond obvious XD -. Perhaps MERRA datas are going to show a little miracle, against the reanalysis, but is not really likely.

So without any surprise, MERRA2 data backup NCEP/NCAR reanalysis and confirm that the Arctic suck up energy at an impressive pace in June. The first graph updates the scatter plot of September sea ice extent by the NSIDC, versus the June surface net downward solar flux (with a reverse scale on the left, in blue). As forecasted, Arctic (northward of 70°N) surface solar flux reached 120 W/m², a new record. The second and third graph are a quick comparison of accumulated heat in 2019, 2016, and 2012. And last, the map for June 2019, showing the strong signal in Beaufort, Chukchi and Laptev.

This heat will probably have long lasting consequences. It can be noted that the halocline is showing signs of disruption, even in the Beaufort sea :

https://www.whoi.edu/page.do?pid=163197

And in the Chukchi sea, the warmth is even more impressive and is mixing to great depth (up to 100 meters), with major disruption of the halocline probably going on.

In the immediate future, the strong dipole (with a forecasted 50kt jet at 850 hPa ! https://www.tropicaltidbits.com/analysis/models/gfs/2019072212/gfs_mslp_uv850_namer_17.png )  is probably going to help mixing, and hence melting in connection with the warm sea.

P.S. : From a more aesthetic view of the weather, it can be noted that a shallow low is going to "deepen" (around 1000 hPa) over the northern slopes of Alaska due to interaction of the southerly flow with mountains. This low is going to accelerate the flow, with a funneling effect along the coast. Independently from the mentioned jet over Arctic, a strong gale is going to develop over Beaufort and Chukchi sea. Given the situation, mean wind of up to 40 kt at surface seems almost reasonable, but given that the wind is going to blow over open sea this can become quite an event. https://www.tropicaltidbits.com/analysis/models/gfs/2019072212/gfs_mslp_wind_ak_19.png It does not always need a deep low for winds reaching high values.
« Last Edit: July 23, 2019, 12:08:40 AM by aslan »

bbr2314

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Re: The 2019 melting season
« Reply #4347 on: July 23, 2019, 12:02:13 AM »
HYCOM has actually been quite useful this year IMO and it portended the complete implosion of the PAC front very accurately. Now it is showing the same happening on the ATL front NE of Greenland, with concentrations dropping to 50% or so across a very wide area over the next week. We have had enough thickness on the ATL front til now to avoid this, but it appears as though we may finally see a collapse in the next week or so. The forecast from GFS / EC/ CMC support this as well. The Laptev front also appears ready to collapse, and all the PAC front that is still above 15% is rapidly going to drop below that number. I would anticipate multiple double / triple-century drops in extent over the next ten days and sustained 100K+ area drops accompanying.


Michael Hauber

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Re: The 2019 melting season
« Reply #4348 on: July 23, 2019, 12:07:34 AM »
Going Sea by Sea:

Beaufort - large amounts of dispersion, but also mostly larger floes, and weather has mostly been cooler in this region.  I suspect the ice is thicker and more durable than might be assumed at first glance looking at the broken appearance.  However the forecast high will hit this hard with heat and sun going into all that open water between the floes.  In 2012

Chukchi - the big story of the season with an ice boundary much further advanced than anything seen before.  Ice floes are much smaller than Beaufort, there is a lot of dispersion on the edge.  The forecast high will hit this area with heat, sun and wind, and the ice slaughter will continue.

ESS - Very weak ice, and an ice edge that has advanced further than 2012, but not as far as 2007.  Bore the brunt of early heatwaves, has been under low pressur and clouds since and the forecast continues this.  Ice would appear to be too weak to survive even under mostly favourable conditions.

Laptev - had a massive start early in June, but has been partly protected in the last few weeks.  A burst of warm air is pushed into this region with a sharp low early in the forecast which will do some more damage, but overall I see this region has fallen behind 2012 which had significant dispersion deep in the pack.  This year is a little like 2007 which had weaker melt in this region due to weather patterns pushing ice towards the Atlantic side, however NE passage remained blocked in this region in 2007 even at minimum and is now open (or at least very close to it).

CAB - the mystery.  Previous heat hasn't impacted this region as much, although there have been at least a couple significant warm incursions.  The forecast hits this region quite hard and it will be under serious assault from at least the Chukchi direction.  Perhaps the ice in this region is healthy enough to slow the melt down and prevent a record.  Or perhaps I'm clutching at straws.    Have a look at this region and compare to some other years.  Dispersion starting on top and left edge, 2012 maybe a little ahead, especially towards top right.  2016, 2008 and 2010 also have some significant dispersion much deeper into this region.  And 2010 wasn't a big melt year so no guarantees that this means anything.
Climate change:  Prepare for the worst, hope for the best, expect the middle.

Paddy

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Re: The 2019 melting season
« Reply #4349 on: July 23, 2019, 12:48:35 AM »
I would anticipate multiple double / triple-century drops in extent over the next ten days and sustained 100K+ area drops accompanying.



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