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b_lumenkraft

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Re: The 2019 melting season
« Reply #2750 on: June 28, 2019, 05:03:43 PM »
Cliff Hanger!

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Re: The 2019 melting season
« Reply #2751 on: June 28, 2019, 05:11:53 PM »
1 week after solstice. Where will the black line? 5-day forecast shows an anticyclone in the centre with vacuum cleaner on the Atlantic side.

Frivolousz21

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Re: The 2019 melting season
« Reply #2752 on: June 28, 2019, 05:15:54 PM »
How is that insolation anomaly created.

Are we using something to determine if there was clear skies or not
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Re: The 2019 melting season
« Reply #2753 on: June 28, 2019, 05:28:36 PM »
So Slater's map has probabilities, but it more or less means (I know it does not, but we can think of it as if)the circled area is likely to have ice with pretty mushy ice up to the NP on aug 17 (for comparison we had this in 2016 on the same date:

magnamentis

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Re: The 2019 melting season
« Reply #2754 on: June 28, 2019, 05:32:44 PM »
How is that insolation anomaly created.

Are we using something to determine if there was clear skies or not

good question, i think it's based on the area of open water but am as well curious to learn the facts here.

however it is, those graphs correspond very well with those of ice melt hence can be considered at least very useful, perhaps even accurate.

let's see and thanks for asking, looking forward to someone with the necessary know-how replying.

AmbiValent

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Re: The 2019 melting season
« Reply #2755 on: June 28, 2019, 05:35:08 PM »
Ummm... I have a question about the discussion of when we should pay attention to data or prediction. Shouldn't we pay prime attention to the present when considering new record bad conditions?

It seems to me that predictions are nice to have, but it's not like they're actual data, and it's also not like we could avert anything by knowing the prediction a few days in advance. And predictions that fail to manifest seem to harm credibility.

On the other hand, looking at data afterwards often comes with comments like "it was bad, but it's getting better now". Gee, usually a new record is followed by a reversal to the mean. But that doesn't mean everything is well, because it's a decreasing mean which means just the regular up and down WILL bring new records, we're just not sure exactly when.

So I think one should look at the present, and note the records. And every new record is more evidence that there can be no true recovery unless the causes for the crisis change.
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Lord M Vader

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Re: The 2019 melting season
« Reply #2756 on: June 28, 2019, 05:44:38 PM »
Jim Hunt: see post my #2369 from June 23 where I posted the link from Zack Labe wrt SIPN prediction. Of course, I should have mentioned that one of the posts was wrt to SIPN.

With warm southerlies entering from Pacific the question is hiw much damage the ice will take? Especially the weak "arm" in western CAB will be of particular interest.

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Re: The 2019 melting season
« Reply #2757 on: June 28, 2019, 05:46:11 PM »
Here is an update of 2012 vs 2019 temps for June.

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Pagophilus

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Re: The 2019 melting season
« Reply #2758 on: June 28, 2019, 06:00:05 PM »
...
With a 1,000 miles of continuous 20knot winds blow through the strait, some of that warmth is moving east and then toward the ESS after it hits the Arctic.

How does it impact the ice in the near term? I'm not sure. The Bering Strait is pretty shallow so the heat may dissipate quickly when mixing with deeper water. There's also the possibility that the remainder of the coastal ice in the ESS will blink out pretty quickly.

Something to keep an eye on.
Actually there's another branch of surface  flow from the Bering Sea that feeds the Alaskan Coastal Current and mixes with Beaufort waters...

Woods Hole Oceanus article https://www.whoi.edu/oceanus/feature/a-ticking-time-bomb-in-the-arctic/  addresses a directly related issue: the warming of the Chuckchi sea via insolation, which must have been even more extreme this year given how early ice was lost there.  This issue is described as a 'ticking time bomb' by John Toole, a scientist at Woods Hole.   

The forecast weather event you describe will be layered on top of this.   

petm

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Re: The 2019 melting season
« Reply #2759 on: June 28, 2019, 06:00:36 PM »
So who is the next?

I think we may need to rename the Laptev "bite" to something more substantial: Feast? Devour? CAA also crashing fast. And the overall forecast curve continues to accelerate downward (positive 2nd derivative) when it ought to be leveling out.

Would be cool to make an animation of Slater's forecast map. Don't suppose anyone has an archive that they could share?
« Last Edit: June 28, 2019, 06:08:47 PM by petm »

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Re: The 2019 melting season
« Reply #2760 on: June 28, 2019, 06:19:56 PM »
The 12z gfs drops a sizeable but weak low pressure system into the CAB around day 7.

This would finally bring some relief to the basin.


Edit.  It quickly dies in the far Southern CAB.

The earlier gfs runs did this.

But the ensembles kept the dipole going.

We'll see.  The models have been doing this for almost 2 weeks before dropping/curtailing it as we get closer.
« Last Edit: June 28, 2019, 06:26:24 PM by Frivolousz21 »
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anaphylaxia

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Re: The 2019 melting season
« Reply #2761 on: June 28, 2019, 06:23:58 PM »
Whats up with the weird dark structures in the laptev fast ice? If I didn't know better, it would look like land masses showing through. What actually causes this?

Thats precisely that, landfast ice. ESS is very shallow on the shelf, less than 10 m at parts. You can see smaller landfast ice fragments, blocking the way of floating ice further down New Siberian Island, like at this point https://worldview.earthdata.nasa.gov/?p=arctic&l=VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Terra_CorrectedReflectance_TrueColor,Reference_Labels(hidden),Reference_Features(hidden),Coastlines&t=2019-06-25-T00%3A00%3A00Z&z=3&v=-671680.3170317126,1506201.7460831201,-425920.3170317126,1627545.7460831201

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Re: The 2019 melting season
« Reply #2762 on: June 28, 2019, 06:30:51 PM »
^^ I've been wondering why that island wasn't on the maps .. :) b.c.
2007 + 5 = 2012 + 4 = 2016 + 3 = 2019 ...

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Re: The 2019 melting season
« Reply #2763 on: June 28, 2019, 06:34:32 PM »
How is that insolation anomaly created.

Are we using something to determine if there was clear skies or not

No. As far as I understand it, it is potential albedo according to the ice and time of the year assuming  no cloud cover.
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gerontocrat

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Re: The 2019 melting season
« Reply #2764 on: June 28, 2019, 06:43:54 PM »
How is that insolation anomaly created.

Are we using something to determine if there was clear skies or not
Tealight did it. Over simplified explanation below.
Uses the area data and applies the standard insolation parameters to each bit of data with albedo dependent on open water or ice.

It is Albedo Warming POTENTIAL. -  does not take into account cloudiness. So actuality by definition must be less. There must be clouds somewhere. If you have a few billion bucks lying around doing nothing I guess somwhere somone might sort the cloudiness thing out. But looks damn complicated given the varying natire of clouds.

But it is telling us that the direction of travel this year is DOWN even given average weather.
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Re: The 2019 melting season
« Reply #2765 on: June 28, 2019, 06:48:00 PM »
Ummm... I have a question about the discussion of when we should pay attention to data or prediction. Shouldn't we pay prime attention to the present when considering new record bad conditions?

It seems to me that predictions are nice to have, but it's not like they're actual data, and it's also not like we could avert anything by knowing the prediction a few days in advance. And predictions that fail to manifest seem to harm credibility.

AmbiValent, you have a strong point about in your urging us to pay attention to actual data, in my view, and that is what the area and extent thread is all about, and the PIOMAS update thread to a lesser degree.  I have argued the point myself.  I think that most posters on this thread also pay close attention to data, but ... it is also interesting and instructive and just plain fun to look ahead.  Scientists don't just analyze data retroactively, they test their understanding by making predictions and seeing how they work out.  You are right, however, in saying that sometimes people get carried away and I agree this can trivialize this thread. 

Weather forecasts up to three or five days into the future are often reliable, and as we see those unfurl in real time I find I learn a lot.  As magna recently reminded us, and as Sterks does on a regular (and needed) basis, forecasts more than 5 days into the future are not so reliable, and if they are seized upon as near certainties then posters are often proven incorrect and this leads to the 'well it wasn't as bad as we thought' revisionism, or just plain unembarrassed radio silence.  The same can apply when a sudden event, like the recent ice fragmentation in the ESS, lead some of us to think 'Oh boy, this is it!' and then more experienced hands remind us that in fact the ice is often more resilient than we think.  I have been guilty of this myself, and am gradually learning and gaining experience.

So, agreed on the centrality of data.  But I think it is not just fine, but scientifically healthy to make well-reasoned, thoughtfully calibrated predictions.  And if some of those don't turn out to be 'true', that is the way it is with predictions and we are still actively learning ...


Pagophilus

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Re: The 2019 melting season
« Reply #2766 on: June 28, 2019, 06:59:23 PM »
How is that insolation anomaly created.

Are we using something to determine if there was clear skies or not
Tealight did it. Over simplified explanation below.
Uses the area data and applies the standard insolation parameters to each bit of data with albedo dependent on open water or ice.

It is Albedo Warming POTENTIAL. -  does not take into account cloudiness. So actuality by definition must be less. There must be clouds somewhere. If you have a few billion bucks lying around doing nothing I guess somwhere somone might sort the cloudiness thing out. But looks damn complicated given the varying natire of clouds.

But it is telling us that the direction of travel this year is DOWN even given average weather.

Eyeballing the overall Arctic basin, and using the patented Pagophilus Cloud Meter (me) I would say that cloud cover has been very low over the past week.  So, lots of lovely summer solstice sunshine for the ice, 24 hours a day.

BTW, although I agree that cloud detection on an icy background is not an easy thing to do, I think some sort of instrument might be readily adapted or built.  It might even use already-existing Worldview imagery.  At this point in the year, many clouds are brighter than the rapidly bluing/graying ice.  Even if the results were not fully definitive with respect to cloud cover, the data might provide a useful year on year basis of comparison.

(Pagophilus now leaps nimbly to the back of the group of posters lest he be volunteered for this task).   
« Last Edit: June 28, 2019, 07:07:18 PM by Pagophilus »

Steven

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Re: The 2019 melting season
« Reply #2767 on: June 28, 2019, 07:14:54 PM »
SIPN Sea Ice Outlook June 2019 report is out.

https://www.arcus.org/sipn/sea-ice-outlook/2019/june

Do we have a thread for discussing these reports? Sorry I couldn't find any, at least not more recent than 2014.

See this thread:
https://forum.arctic-sea-ice.net/index.php/topic,2719.msg207635.html#msg207635

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Re: The 2019 melting season
« Reply #2768 on: June 28, 2019, 07:31:33 PM »
Quote
Eyeballing the overall Arctic basin, and using the patented Pagophilus Cloud Meter (me) I would say that cloud cover has been very low over the past week.  So, lots of lovely summer solstice sunshine for the ice, 24 hours a day.

BTW, although I agree that cloud detection on an icy background is not an easy thing to do
Albedo over ice is small (low?) and putting clouds over it will reduce it some.  Clouds over open water, however, would be 'significant'.
Arctic ice is healthy for children and other living things.

petm

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Re: The 2019 melting season
« Reply #2769 on: June 28, 2019, 07:46:46 PM »
Rain for the next few days on immediately vulnerable areas of the Pacific, Atlantic (S. of Svalbard), Laptev, and CAA. Will this accelerate near-term melting?

Frivolousz21

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Re: The 2019 melting season
« Reply #2770 on: June 28, 2019, 07:49:28 PM »
The 12Z gfs ensemble mean says the OP breaking down the dipole is bullshit.



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AmbiValent

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Re: The 2019 melting season
« Reply #2771 on: June 28, 2019, 07:52:43 PM »
<snip>
So, agreed on the centrality of data.  But I think it is not just fine, but scientifically healthy to make well-reasoned, thoughtfully calibrated predictions.  And if some of those don't turn out to be 'true', that is the way it is with predictions and we are still actively learning ...
I agree, it's scientifically important to continuously test models and prediction to see which ones work best, and possibly which factors played a role in it. This doesn't mean the ones we have right now are bad, but that they can still be improved.
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Re: The 2019 melting season
« Reply #2772 on: June 28, 2019, 07:53:27 PM »

AmbiValent, you have a strong point about in your urging us to pay attention to actual data, in my view, and that is what the area and extent thread is all about, and the PIOMAS update thread to a lesser degree. ...
.

The extent and data thread is an extremely limited perspective on data

Air temperature, ocean temperature, wind direction and speed, insolation, air pressure, ice thickness, concentration, currents, etc. all come into play to form a holistic understanding of what's going on.

I admit I'm not a huge fan of 10 day forecasts, but there are worse things to deal with.

gerontocrat

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Re: The 2019 melting season
« Reply #2773 on: June 28, 2019, 07:54:34 PM »

BTW, although I agree that cloud detection on an icy background is not an easy thing to do, I think some sort of instrument might be readily adapted or built.  It might even use already-existing Worldview imagery.  At this point in the year, many clouds are brighter than the rapidly bluing/graying ice.  Even if the results were not fully definitive with respect to cloud cover, the data might provide a useful year on year basis of comparison.

(Pagophilus now leaps nimbly to the back of the group of posters lest he be volunteered for this task). 
Somewhere on this forum I am sure there is a discussion on just how difficult it is to measure the amount and type of radiation getting through clouds. I believe there are products out there producing estimates, but their usefulness is questioned.

But I haven't got a billion or two bucks to spare, so you are on your own, pal. Well volunteered.
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Re: The 2019 melting season
« Reply #2774 on: June 28, 2019, 07:56:24 PM »
Rain for the next few days on immediately vulnerable areas of the Pacific, Atlantic (S. of Svalbard), Laptev, and CAA. Will this accelerate near-term melting?

Yeah anywhere ot rains And the liquid isn't "super cooled" will be bad
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petm

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Re: The 2019 melting season
« Reply #2775 on: June 28, 2019, 08:07:55 PM »
Yeah anywhere ot rains And the liquid isn't "super cooled" will be bad

How can we tell if the rain might be super cooled? Temps (e.g.) in the Pacific sector for the next few days are forecast above freezing up to 850 hPa.

Pagophilus

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Re: The 2019 melting season
« Reply #2776 on: June 28, 2019, 08:19:03 PM »
Quote
Eyeballing the overall Arctic basin, and using the patented Pagophilus Cloud Meter (me) I would say that cloud cover has been very low over the past week.  So, lots of lovely summer solstice sunshine for the ice, 24 hours a day.

BTW, although I agree that cloud detection on an icy background is not an easy thing to do
Albedo over ice is small (low?) and putting clouds over it will reduce it some.  Clouds over open water, however, would be 'significant'.
Agreed!   Ocean albedo is very low, about 0.06 (maybe effectively higher in the Arctic because of the low angle of insolation, but not much.  Sea ice albedo varies from 0.5 to 0.7 so MUCH higher reflectance (50-70% incoming radiation).   However, it does therefore absorb 30-50%, and when we consider the vast area of Arctic ice that is a huge amount of energy on a daily basis.  I would argue that that is significant on a seasonal basis, if the ice pack remains under clear skies for a long period of time.  However, I don't have the experience to know how much this factors in compared to the other melting stressors the ice comes under at this time.   :)

Frivolousz21

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Re: The 2019 melting season
« Reply #2777 on: June 28, 2019, 08:35:31 PM »
Yeah anywhere ot rains And the liquid isn't "super cooled" will be bad

How can we tell if the rain might be super cooled? Temps (e.g.) in the Pacific sector for the next few days are forecast above freezing up to 850 hPa.

Basically when the rain drops reach the surface they are ready to freeze on contact.

As if they are about to freeze while falling.  This rain would be cold enough that it would later have to be warmed up by the atmosphere

Or warmed by melt pond water on the ice surface.

If 850s are above freezing then they wont be supercooled.

Even if it's 33-34F that would be very bad for the ice.

Since it's freezing point is roughly 29F.


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Re: The 2019 melting season
« Reply #2778 on: June 28, 2019, 08:56:16 PM »
Friv, is "supercooled" different than freezing rain?

https://climatereanalyzer.org/wx/fcst/#gfs.arc-lea.prcp-mslp-gph500

According to GFS forecast above there is only a small area of freezing rain(pink) in the system that also briefly flashes to snow, over Beaufort sea open water... the rest looks like it will be coming down as regular bad-for-the-ice rain.
« Last Edit: June 28, 2019, 09:22:42 PM by Sarat »

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Re: The 2019 melting season
« Reply #2779 on: June 28, 2019, 08:59:17 PM »
RE Pagphilus post #2776 on Albedo

   - At Reply #55  in "Atmospheric connections, structure, and long range weather forecasting" you can see abstracts of two recent studies on the effect of current (as 2011) and future (ice free summer Arctic Ocean in ?) albedo change from Arctic sea ice decline on global energy balance. 
« Last Edit: June 28, 2019, 09:20:58 PM by Glen Koehler »

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Re: The 2019 melting season
« Reply #2780 on: June 28, 2019, 09:05:28 PM »
Tealight's "Albedo warming potential" takes into account open water, ice and I believe also snow. But not cloud cover.
Edit: Of course Tealight also takes into account latitude and insolation.
You don't need a billion or two to assimilate cloud cover into the model - this is what PIOMAS does. Of course, the devil is in the details - is the cloud cover data accurate? Is radiation through clouds mdoeled correctly? But PIOMAS already attempts to be a full model of energy transfer and ice movements.
Quote
Sea Ice Volume is calculated using the Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS, Zhang and Rothrock, 2003) developed at APL/PSC.


Model and Assimilation Procedure

PIOMAS is a numerical model with components for sea ice and ocean and the capacity for assimilating some kinds of observations. For the ice volume simulations shown here, sea ice concentration information from the NSIDC near-real time product are assimilated into the model to improve ice thickness estimates and SST data from the NCEP/NCAR Reanalysis are assimilated in the ice-free areas.  NCEP/NCAR reanalysis SST data are based on the global daily high-resolution Reynolds SST analyses using satellite and in situ observations (Reynolds and Marsico, 1993; Reynolds et al., 2007). Atmospheric information to drive the model, specifically wind, surface air temperature, and cloud cover to compute solar and long wave radiation are specified from the NCEP/NCAR reanalysis. The pan-Arctic ocean model is forced with input from a global ocean model at its open boundaries located at 45 degrees North.
« Last Edit: June 28, 2019, 09:58:45 PM by oren »

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Re: The 2019 melting season
« Reply #2781 on: June 28, 2019, 09:26:21 PM »
Yeah anywhere ot rains And the liquid isn't "super cooled" will be bad

How can we tell if the rain might be super cooled? Temps (e.g.) in the Pacific sector for the next few days are forecast above freezing up to 850 hPa.

If 850s are above freezing then they wont be supercooled.

Even if it's 33-34F that would be very bad for the ice.

Right -- I just wasn't sure which pressure levels to look at. In the Chukchi area were it will be raining, for the duration of the event (now to 4+ days), temps are forecast (GFS via nullschool) to be well above freezing: 2-4+ degrees Celsius (35-40+ F), right from surface to above 850 hPa.

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Re: The 2019 melting season
« Reply #2782 on: June 28, 2019, 09:28:28 PM »
Sea ice concentration, June 13 – June 27

Laptev melt is particularly striking
« Last Edit: June 29, 2019, 03:58:30 AM by cavitycreep »

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Re: The 2019 melting season
« Reply #2783 on: June 28, 2019, 09:45:23 PM »
WRT cloud cover / albedo found these a while ago, i haven't had time to really go through them but it looks interesting...

http://www.cloudsat.cira.colostate.edu/

http://www.cloudsat.cira.colostate.edu/community-products/arctic-observation-and-reanalysis-integrated-system


Quote
(Pagophilus now leaps nimbly to the back of the group of posters lest he be volunteered for this task). 

Now I'm joining Pagophilus and ducking :)

petm

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Re: The 2019 melting season
« Reply #2784 on: June 28, 2019, 09:55:07 PM »
Friv, is "supercooled" different than freezing rain?

Yes, I'm pretty sure he means freezing rain (liquid with below-freezing temp).

By the way, is freezing rain good for ice preservation, neutral, or depends?

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Re: The 2019 melting season
« Reply #2785 on: June 28, 2019, 10:16:49 PM »
EC 12z ensemble is just brutal for the next 5 days. The heat is just walking around the Arctic. CAA and Chukchi sea should take a major hit.

EC 12z op has some more cyclonic activity in the later range which might be the only hope for the Arctic to put some brake at this melting season and prevent a new record low in September. At least, we have to look for some good signs even if it is far out.

be cause

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Re: The 2019 melting season
« Reply #2786 on: June 28, 2019, 10:24:38 PM »
supercooled rain would be good for the ice as it would freeze on contact and create a glassy surface . My one experience of it in 1979 left my hair breakable and my return journey on foot impossible .
 I understand freezing rain to have frozen while falling and act more like hail on impact . That I have experienced more often . b.c.

btw .. the pole-centric dmi80 today was a full 1'C above freezing for the 1st time this year .
« Last Edit: June 28, 2019, 10:55:09 PM by be cause »
2007 + 5 = 2012 + 4 = 2016 + 3 = 2019 ...

Frivolousz21

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Re: The 2019 melting season
« Reply #2787 on: June 28, 2019, 11:00:22 PM »
EC 12z ensemble is just brutal for the next 5 days. The heat is just walking around the Arctic. CAA and Chukchi sea should take a major hit.

EC 12z op has some more cyclonic activity in the later range which might be the only hope for the Arctic to put some brake at this melting season and prevent a new record low in September. At least, we have to look for some good signs even if it is far out.

It is brutal.

Even with a bit of cyclonic activity its still boiling all over every the Russian shelf where it's to late anyways.

The CAA and CAB are going to get hammered.

The CAA and Beaufort really get crushed and the Beaufort is already boiling
I got a nickname for all my guns
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Pavel

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Re: The 2019 melting season
« Reply #2788 on: June 28, 2019, 11:26:24 PM »
The strong High Pressure Will cause damage to the FYI at the North Pole. Combined with the hight Fram export we'll have many holes at the Pole by the end of July. I also think all peripheral seas Will melt out completely (some MYI could be exported to the Beaufort). Looks like 2019 Will take the title in September

uniquorn

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Re: The 2019 melting season
« Reply #2789 on: June 28, 2019, 11:47:25 PM »
worldview aqua modis, caa-cab crack, jun28, light contrast. https://go.nasa.gov/2Xbnxzu

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Re: The 2019 melting season
« Reply #2790 on: June 28, 2019, 11:47:58 PM »
I posted this in the Nares thread.
This place (right where the Strait meets the Baffin polynya) is so singular that to my belief it is the only NH place where extent has increased during June. By an accretion mechanism, ice floes stick to the fast ice at a low velocity point surrounded by very chaotic currents.

It is melting, so probably won’t clog the Strait
« Last Edit: June 28, 2019, 11:56:05 PM by Sterks »

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Re: The 2019 melting season
« Reply #2791 on: June 28, 2019, 11:53:44 PM »
I've been following this forum quietly since about 2012. This year is starting to get pretty scary. The activity on this thread is massive compared to the slow years. We're in for a ride here, there is no way around it, the ice just looks terrible.

Kate

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Re: The 2019 melting season
« Reply #2792 on: June 29, 2019, 02:26:42 AM »
How is that insolation anomaly created.

Are we using something to determine if there was clear skies or not

Eyeballing the overall Arctic basin, and using the patented Pagophilus Cloud Meter (me) I would say that cloud cover has been very low over the past week.  So, lots of lovely summer solstice sunshine for the ice, 24 hours a day.

BTW, although I agree that cloud detection on an icy background is not an easy thing to do, I think some sort of instrument might be readily adapted or built.  It might even use already-existing Worldview imagery.  At this point in the year, many clouds are brighter than the rapidly bluing/graying ice.  Even if the results were not fully definitive with respect to cloud cover, the data might provide a useful year on year basis of comparison.

(Pagophilus now leaps nimbly to the back of the group of posters lest he be volunteered for this task). 

I have always wondered if the forum contains a cloud expert who could advise on the expected conditions of certain clouds over ice and what the expected results locally would be. Although it's another 'model' it could be a handy addition.

subgeometer

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Re: The 2019 melting season
« Reply #2793 on: June 29, 2019, 02:53:56 AM »
All of a sudden, everybody rushes for the exit door

Today's ECMWF forecast on WindyTV is worse than the last re export, with constant brisk northerlies blowing through Fram Straitevery day except(haha) D10

subgeometer

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Re: The 2019 melting season
« Reply #2794 on: June 29, 2019, 03:10:33 AM »
How is that insolation anomaly created.

Are we using something to determine if there was clear skies or not

It didn't in 2016 when this thread was created by Tealight https://forum.arctic-sea-ice.net/index.php/topic,1749.0.html

Edit: It seems it basically calculates the open water areas for each day(or at least did then, I haven't time to read through the thread right now) and multiplies that by the incoming insolation for the date. Leaving out cloud cover makes it an imperfect tool. if the Laptev Sea had been cloudy over the past week, it wouldn't be close to the temperature it is now. Maybe there's a band on worldview where pixel counting could give a value for cloud cover, I'm not sure
« Last Edit: June 29, 2019, 03:26:22 AM by subgeometer »

Pragma

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Re: The 2019 melting season
« Reply #2795 on: June 29, 2019, 03:14:16 AM »
All of a sudden, everybody rushes for the exit door

Today's ECMWF forecast on WindyTV is worse than the last re export, with constant brisk northerlies blowing through Fram Straitevery day except(haha) D10

I noticed that too. At various times, it will be pulling ice from the CAB area in almost a full semi-circle, 90 degrees each way from middle at Fram with the centre of the circle at the pole. The first few days concentrate on the west side and then it will be clearing out the ice south of the Svalbard to FJL line and beyond. The winds are most intense in the first 3 days but it is a steady 16 kt (30 km/h) for about a week.

This combined with warm winds coming in from the Bering Sea means that the ice will look very different a week from now.

subgeometer

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Re: The 2019 melting season
« Reply #2796 on: June 29, 2019, 03:32:42 AM »
All of a sudden, everybody rushes for the exit door

Today's ECMWF forecast on WindyTV is worse than the last re export, with constant brisk northerlies blowing through Fram Straitevery day except(haha) D10

I noticed that too. At various times, it will be pulling ice from the CAB area in almost a full semi-circle, 90 degrees each way from middle at Fram with the centre of the circle at the pole. The first few days concentrate on the west side and then it will be clearing out the ice south of the Svalbard to FJL line and beyond. The winds are most intense in the first 3 days but it is a steady 16 kt (30 km/h) for about a week.

This combined with warm winds coming in from the Bering Sea means that the ice will look very different a week from now.

To me that sounds more like yesterday's forecast. There are more period of 20+ kt wind on today's with 2-stepping lows between Svalbard and Scandinavia revving it up a bit more. Otherwise its as you descibe

subgeometer

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Re: The 2019 melting season
« Reply #2797 on: June 29, 2019, 03:41:50 AM »
Jim Hunt: see post my #2369 from June 23 where I posted the link from Zack Labe wrt SIPN prediction. Of course, I should have mentioned that one of the posts was wrt to SIPN.

With warm southerlies entering from Pacific the question is hiw much damage the ice will take? Especially the weak "arm" in western CAB will be of particular interest.

That wind from the Pacific brings a LOT of precipitable moisture, the air column over open water area of the Chukchi will be dripping with20-30kg/m2 of water, that's the average over the next 5days according to GFS. And a lot of it will be dumped as rain on the ice front, including that weak arm.

I've attached 5 day precipitation and precipitable water forecasts from GFS/Climate Reanalyser

subgeometer

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Re: The 2019 melting season
« Reply #2798 on: June 29, 2019, 04:08:11 AM »
A quick and dirty insolation calculation could made by making a grayscale version of Worldview's truecolor image for the date, then iterating over the pixels inside a mask(that excludes areas outside the sea ice area, or area of interest), and multiplying their albedo/darkness by insolation at that date and latitude.

Edit:  Then you don't have to handle clouds explicitly. Fixed a few typos

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Re: The 2019 melting season
« Reply #2799 on: June 29, 2019, 04:44:43 AM »
For what it's worth, I created a separate thread with a straw man suggestion for evaluating melting seasons. I'd be interested in feedback if anyone is interested.

The idea is that this would ground analysis of what's going in the fundamental drivers of the melting outcome and make it easier for newbies to follow along. As a relatively new participant here, there's a sense that the discussion is sometimes over complicated or oblique in ways that are unnecessary.

Ultimately, melting can be reduced to a finite number of root causes that should be relatively straight forward for a newbie to grasp.