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gerontocrat

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Re: The 2020 melting season
« Reply #2100 on: July 03, 2020, 01:08:46 PM »
That is the problem though, it's the old high pressure = sunshine yet its not always that simple. There will be sunny areas for sure, I'm not quite sure how strong the sunshine is at higher latitudes compared to lower latitudes but one would imagine it be less strong?
But 24 hour daylight - attached is the graph from tealight looking at insolation at the surface according to latitude, i.e. taking account of energy absorption by the atmosphere.
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Pagophilus

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Re: The 2020 melting season
« Reply #2101 on: July 03, 2020, 01:14:48 PM »
NSIDC comparison tool, July 1 2020 vs. July 1 2016, and vs July 1 2012.

The same broad differences persist between 2020 and these two other years (more ice on the Atlantic and the Beaufort Sea in 2020, with the extraordinary loss in the Laptev standing out, and with a much smaller relative losses in the ESS and Chukchi).  Most of the Kara is virtually melted out in all three years.  I could not get the tool to produce a 2019 comparison.  Obviously comparing 2020 with eventual record low minimum years here...
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ArcticMelt2

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Re: The 2020 melting season
« Reply #2102 on: July 03, 2020, 01:21:16 PM »
In 2014, there was weak melting (minimum about 5 million km2), although the edge of sea ice receded to 85 degrees.

In general, there was only 5 years when the ice edge receded to 85 parallel: 2007, 2012, 2013, 2014 and 2016.

So the current melting season will in any case be one of the worst.

gandul

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Re: The 2020 melting season
« Reply #2103 on: July 03, 2020, 01:43:18 PM »
In 2014, there was weak melting (minimum about 5 million km2), although the edge of sea ice receded to 85 degrees.

In general, there was only 5 years when the ice edge receded to 85 parallel: 2007, 2012, 2013, 2014 and 2016.

So the current melting season will in any case be one of the worst.
2014 was a pretty cold season in general, with slow melting and a central high in July that was pretty weak, allowing for a constant fog that protected the ice.
With the strong subsidence predicted I don't see the same behavior this year. But who knows, if the high perpetuates and morphs into a weak persistent high we may see the same sort of protection, but I don't think so.

gandul

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Re: The 2020 melting season
« Reply #2104 on: July 03, 2020, 01:54:58 PM »
I can envisage a record of this indicator by 10th of July
I surely have not seen over MODIS the way Arctic ice ooks right now, not certainly in 2014!!

The high extent cover over Beaufort is probably gonna save the ice from a new record this time.
Edit. Just look at that surface wetness strip from Laptev reaching the Pole... Whoa
As the beige pixels are running out, it may be interesting to include information from the other pixel colors as well.  The graph below plots a weighted sum of all the sea ice pixels in the SMOS images, as discussed upthread last year:



https://www.dropbox.com/s/010xfjx6wo90ysy/smos_weighted_2020.png
« Last Edit: July 03, 2020, 02:27:30 PM by gandul »

ArcticMelt2

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Re: The 2020 melting season
« Reply #2105 on: July 03, 2020, 02:24:56 PM »
In 2014, there was weak melting (minimum about 5 million km2), although the edge of sea ice receded to 85 degrees.

In general, there was only 5 years when the ice edge receded to 85 parallel: 2007, 2012, 2013, 2014 and 2016.

So the current melting season will in any case be one of the worst.
2014 was a pretty cold season in general, with slow melting and a central high in July that was pretty weak, allowing for a constant fog that protected the ice.
With the strong subsidence predicted I don't see the same behavior this year. But who knows, if the high perpetuates and morphs into a weak persistent high we may see the same sort of protection, but I don't think so.

Yes, of course, 2014 looks weaker than 2020 in the Laptev Sea. For example, is fast ice in mouth of the Khatanga River and the Strait of Cape Chelyuskin. Then probably the southern wind played a big role. Nevertheless, this is a vivid example that the rapid melting of ice in the Laptev Sea is not a guarantee of a record in September.

Aluminium

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Re: The 2020 melting season
« Reply #2106 on: July 03, 2020, 02:28:49 PM »
AWP anomaly in the Laptev Sea is huge. The CAB seems to be affected.

Pagophilus

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Re: The 2020 melting season
« Reply #2107 on: July 03, 2020, 03:22:16 PM »
Back to to the NSIDC comparison tool just to provide a little more visual information here re recent posts, while wholly respecting the correlation analysis, Arctic Melt.  It is striking to me how similar the ice distributions are in 2014 and 2020 on July 1 (the date the tool made me choose).  But the extent to which the Siberian side, the Laptev and the Kara, have melted out this year still stands out visually vs. even compared with 2014.  BTW: Does early melting of the Kara significantly affect general dynamics of melting in the CAB?


IMO the day-over-day change in Laptev viewable in EOSDIS indicates the impending situation will result in 2020 taking a mile-long lead.

The ice edge is retreating.... extremely quickly. Collapsing may be a better term. The ATL front is collapsing, but the more significant extent and area hammer may soon be all the FYI in the Beaufort and Chukchi which also looks like it is about to give out (or in 30-45 days rather). On satellite this huge area of FYI has now gone very grey and HYCOM indicates it is pretty thin, like a bit over a meter in general.

It must be noted that both Laptev and Kara have almost fully melted as of 7/1. An unprecedented situation. The moat has been crossed, the wall has been breached, the CAB is open for assault from two new directions at peak insolation under most GHG forcing in the modern era combined with a lack of airplane and aerosol-driven clouds relative to normal years.

The year over year comparison is shocking, lol. Laptev just went poof!

I completely agree. Now I’ve looked at the state of the Laptev Sea on July 1, 2012, and it is simply incomparable with the current situation.

This year is most likely to break the 2012 record among any of the last 8 years.

But yesterday, all the same, doubts arose that the 2012 record would be broken. On the second place by the minimum ice extent in the Laptev Sea on July 1, not 2012, 2014 (data NSDIC extent):

2014 is only 50,000 km2 behind 2020. In 2014, there was weak melting (minimum about 5 million km2), although the edge of sea ice receded to 85 degrees.

So fortunately, the 2012 record this year is not in danger. Most likely the forecast according to SMOS for June is the most accurate.

Quote
The June monthly average has a good correlation with the September NSIDC sea ice extent.  The correlation coefficient is 0.86 over 2010-2019  (and even 0.95 if 2010 is excluded).  FWIW, this would give a prediction for the September 2020 NSIDC extent of 4.49 +/- 0.52 million km2 (95% prediction interval).
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ArcticMelt2

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Re: The 2020 melting season
« Reply #2108 on: July 03, 2020, 03:33:00 PM »
Back to to the NSIDC comparison tool just to provide a little more visual information here re recent posts, while wholly respecting the correlation analysis, Arctic Melt.  It is striking to me how similar the ice distributions are in 2014 and 2020 on July 1 (the date the tool made me choose).  But the extent to which the Siberian side, the Laptev and the Kara, have melted out this year still stands out visually vs. even compared with 2014. 

Thanks for the informative diagram.

BTW: Does early melting of the Kara significantly affect general dynamics of melting in the CAB?

I think the Kara Sea has little effect on the amount of summer melting. On the contrary, the Beaufort Sea and the Laptev Sea are key seas, due to the general picture of ice drift Beaufort cycle.

At the moment, the Laptev Sea is leading in all types of regional graphs (extent or area), unlike the Beaufort Sea its ice cover is close to long-term average values.

https://sites.google.com/site/arcticseaicegraphs/regional
« Last Edit: July 03, 2020, 03:41:45 PM by ArcticMelt2 »

JamesW

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Re: The 2020 melting season
« Reply #2109 on: July 03, 2020, 04:08:59 PM »
With the difference between area and extent growing. Is there anyone here that can reproduce the compaction chart that Neven so kindly put up occasionally during the melting season? I think it might be of worth at this point.

Phoenix

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Re: The 2020 melting season
« Reply #2110 on: July 03, 2020, 04:26:32 PM »
AWP anomaly in the Laptev Sea is huge. The CAB seems to be affected.

Yes, Nico is having to revise the upper boundary of this chart on a frequent basis lately.

The AWP anomaly in the Beaufort Sea is also huge in the opposite direction and there we are having a year which is a throwback to 1990's level albedo.

marcel_g

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Re: The 2020 melting season
« Reply #2111 on: July 03, 2020, 05:08:54 PM »

Questions:
Am I correct in thinking that this high pressure system, if it indeed causes mostly clear skies at peak insolation, all while the ice is highly preconditioned compared to other years, will show its effects mostly in August when bottom melt takes over? As in 2012 when the ice losses in the CAB just kept going down and down? while other years levelled off in August?

Am I correct in remembering that this kind of sunshine can cause up to 5cm/day of top melt? So this week long HP could melt 30cm off of wide swaths of the ASI?

If the water under the ice warms up, how much ice starts melting per day? 0.5cm? 1cm? Do we know how fast bottom melt was going in other years, when there were still buoys in the ice measuring such things?

My guess is if 20-30cm melts off the top over the next week, and bottom melt removes 30-60cm off the bottom of the ice over the next 7 or so weeks, there will not be much ice left by volume, and like Friv was saying, the main effect of this HP is going to be on volume. The ice by August will be dispersed slush in a lot of areas.

So if A) this HP does stay relatively clear of clouds, and then B) in August there is some wind bringing waves to the slush and bringing heat up from lower layers of water, there might in fact be much more melting in August than previous years.

gerontocrat

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Re: The 2020 melting season
« Reply #2112 on: July 03, 2020, 05:20:34 PM »
With the difference between area and extent growing. Is there anyone here that can reproduce the compaction chart that Neven so kindly put up occasionally during the melting season? I think it might be of worth at this point.
Forgot I had them on tap....

Total,
High Arctic Seas,
Peripheral Seas.

Mind you, I like my dispersion graphs (= Extent / Area) more
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ArcticMelt2

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Re: The 2020 melting season
« Reply #2113 on: July 03, 2020, 05:36:32 PM »

Questions:
Am I correct in thinking that this high pressure system, if it indeed causes mostly clear skies at peak insolation, all while the ice is highly preconditioned compared to other years, will show its effects mostly in August when bottom melt takes over? As in 2012 when the ice losses in the CAB just kept going down and down? while other years levelled off in August?

Am I correct in remembering that this kind of sunshine can cause up to 5cm/day of top melt? So this week long HP could melt 30cm off of wide swaths of the ASI?

If the water under the ice warms up, how much ice starts melting per day? 0.5cm? 1cm? Do we know how fast bottom melt was going in other years, when there were still buoys in the ice measuring such things?

My guess is if 20-30cm melts off the top over the next week, and bottom melt removes 30-60cm off the bottom of the ice over the next 7 or so weeks, there will not be much ice left by volume, and like Friv was saying, the main effect of this HP is going to be on volume. The ice by August will be dispersed slush in a lot of areas.

So if A) this HP does stay relatively clear of clouds, and then B) in August there is some wind bringing waves to the slush and bringing heat up from lower layers of water, there might in fact be much more melting in August than previous years.


If you have a lot of free time, then look at the situation in the summer of 2008, when there are detailed published data.

http://nsidc.org/arcticseaicenews/2008/08/

Quote
The buoys are deployed as part of the North Pole Environmental Observatory, the Beaufort Gyre Observatory, and the DAMOCLES project. The buoy data have indicated increased amounts of melt on the underside of the ice cover in recent years; bottom melt last year was particularly extreme.

The pattern for 2008 has been more mixed. The ice at some buoy locations has thinned by more than a meter through the melt season because of strong melt both on the surface and the underside of the ice. Other locations show strong thinning caused by surface melt, while only modest thinning is apparent in others. Differences in surface melt from location to location reflect factors such as air temperature, the ice albedo, and cloud conditions. The wide range in bottom melt points to variations in the amount of ocean heat absorbed. In recent days, the buoys have indicated sub-freezing temperatures with surface melt coming to an end; however, bottom melt will continue for at least two to three more weeks and the ice extent decline, while slowing, will also continue.

http://nsidc.org/images/arcticseaicenews/20080825_Figure4.png

Quote
Figure 4. Ice thickness measurements for summer 2008 indicate melt at the ice surface (red) versus the underside (yellow). This image shows changes in ice thickness at buoy locations (white circles), overlaid on the NSIDC sea ice concentration field for August 20. The numbers above each bar plot indicate total ice thickness at the beginning of the melt season compared to August 20.


You can see MODIS images for 2008, weather data for 2008, and compare with the current situation.

grixm

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Re: The 2020 melting season
« Reply #2114 on: July 03, 2020, 05:39:22 PM »
Area anomaly. Useful map that for some reason isn't posted very often.

Freegrass

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Re: The 2020 melting season
« Reply #2115 on: July 03, 2020, 05:50:49 PM »
Last 24 Hours + Five Day Forecast
Wind @ Surface

This Giant AntiCyclone is gorgeous. I've added the last 24 hours as well this time so you could see the destruction that has already happened in the ESS.

Fram export will be brutal if the whole thing starts spinning, but mostly, I just find it a thing of beauty...

Large Gif!
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ArcticMelt2

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Re: The 2020 melting season
« Reply #2116 on: July 03, 2020, 05:56:04 PM »
If you have a lot of free time, then look at the situation in the summer of 2008, when there are detailed published data.

http://nsidc.org/arcticseaicenews/2008/08/


More similar data

http://nsidc.org/arcticseaicenews/2013/09/

Quote
During the summer of 2013 there were six ice mass balance buoys deployed in the Arctic over a wide area (red dots in Figure 5). The buoys were deployed in undeformed, multiyear ice, with a thickness between 2.2 and 3.5 meters (7 and 11 feet) before melt began. Data from the buoys show that the amount of surface ice melting ranged from 0 in the central Arctic, to 75 centimeters (30 inches) in the Beaufort Sea. Bottom melting varied from 8 to 108 centimeters (3 to 43 inches). The largest amount of bottom melting was observed at a buoy near the ice edge in the Beaufort Sea. This buoy had the largest total amount of melt, thinning from 339 centimeters (133 inches) in early June, to 157 centimeters (62 inches) on August 28. Ice thicknesses at the other buoys on August 28 ranged from 121 to 267 centimeters (48 to 105 inches). While bottom melting is continuing in some locations, most of this year’s surface melting has occurred. Data from the ice mass balance buoys are available at http://imb.crrel.usace.army.mil. (Thanks to Jackie Richter-Menge and Don Perovich at the Cold Regions Research and Engineering Laboratory [CRREL] for this part of the discussion.)

http://nsidc.org/arcticseaicenews/files/2000/09/figure5-350x286.png

Quote
Figure 5. This map of the Arctic shows results from six ice mass balance buoys that operated throughout the summer of 2013. A red dot denotes each buoy position on August 28, 2013. The red bars indicate the total amount of summer surface melt and the yellow bars show bottom melt. The white background is the MASIE ice extent on August 28, 2013 mapped on Google Earth.

Credit: NSIDC courtesy Jackie Richter-Menge and Don Perovich/CRREL


It is clearly seen that many such buoys in the Arctic usually unfold, a year after the catastrophic melting. And when nothing interesting happens in the Arctic, there is no funding, no buoys.  :-X


P.S. Data for 2011

http://nsidc.org/arcticseaicenews/2011/08/
« Last Edit: July 03, 2020, 06:02:43 PM by ArcticMelt2 »

ArcticMelt2

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Re: The 2020 melting season
« Reply #2117 on: July 03, 2020, 06:11:47 PM »
https://twitter.com/ZLabe/status/1279081395554357248

Quote
Sea surface temperatures will continue to rise along the Siberian coast due to the unprecedentedly early loss of #Arctic sea ice in this region ---> dark water absorbing sunlight + recent heatwave


Phoenix

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Re: The 2020 melting season
« Reply #2118 on: July 03, 2020, 06:13:07 PM »

Questions:
Am I correct in thinking that this high pressure system, if it indeed causes mostly clear skies at peak insolation, all while the ice is highly preconditioned compared to other years, will show its effects mostly in August when bottom melt takes over? As in 2012 when the ice losses in the CAB just kept going down and down? while other years levelled off in August?

Am I correct in remembering that this kind of sunshine can cause up to 5cm/day of top melt? So this week long HP could melt 30cm off of wide swaths of the ASI?

If the water under the ice warms up, how much ice starts melting per day? 0.5cm? 1cm? Do we know how fast bottom melt was going in other years, when there were still buoys in the ice measuring such things?

My guess is if 20-30cm melts off the top over the next week, and bottom melt removes 30-60cm off the bottom of the ice over the next 7 or so weeks, there will not be much ice left by volume, and like Friv was saying, the main effect of this HP is going to be on volume. The ice by August will be dispersed slush in a lot of areas.

So if A) this HP does stay relatively clear of clouds, and then B) in August there is some wind bringing waves to the slush and bringing heat up from lower layers of water, there might in fact be much more melting in August than previous years.

My take on the current situation....

The current circumstances in the CAB are truly brutal on the ice. It's a combination of high insolation close to the solstice and above average warmth. Doesn't get much worse than that.

In about three days, the heat forecast changes. The high pressure is doing a good job of pushing the lower latitude heat to the south and the CAB will cool somewhat. So the intensity of the melting pressure eases off some.

The intensity of a single week needs to be taken into the context of the ice condition preceding that week. The CAB was in relatively good shape as a whole prior to this past week and is taking a meaningful hit. The NSIDC area numbers are a good indicator of the melting activity which is super high at the moment and should stay that way for several more days.

2020 has had an extremely high top end when it comes to melting power. It's peak powers get an A++. Consistency has been another story in some regions like the all important CAB and the Beaufort Sea.

The September outcome is the result of a starting point and 12 months of activity. I don't think the high intensity of the current moment in the CAB is enough to overwhelm the influence of the entire year. Two more months to go though, we'll see what happens.

PS - If there are some peer reviewed sources which put some algebra to the melting calculations, I'd  love to see them. I question the bottom melt assumptions in your post based upon the ability of EMR to penetrate thicker CAB ice.

JamesW

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Re: The 2020 melting season
« Reply #2119 on: July 03, 2020, 06:18:25 PM »
Thank you gerontocrat for your reply and charts. I wanted a basic overview of these charts as we go through this anomalous high pressure over the basin. Sunlight/Insolation V's Compaction/Dispersion and to understand the impact for future reference.

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Re: The 2020 melting season
« Reply #2120 on: July 03, 2020, 06:20:48 PM »
The latest GFS forecast (July 3rd, 12z) indicates the winds over the next 5 - 7 days are aligned to create a very strong Fram export.   Attached is an example for July 8th.

So this will be in addition to all of the solar insolation that is occurring.

It will be interesting to see what this collectively will do the CAB over the next 7 days.  Certainly bad for the ice, more of a question of how bad.
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GoSouthYoungins

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Re: The 2020 melting season
« Reply #2121 on: July 03, 2020, 06:54:04 PM »
The Siberian Ice area anomaly is just going to increase over the next week. The ice has been getting rapidly obliterated near the lena delta and the winds are taking more ice in that direction. And the winds are opening up "the bite" towards the pole more.   
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Phoenix

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Re: The 2020 melting season
« Reply #2122 on: July 03, 2020, 06:55:10 PM »
The latest GFS forecast (July 3rd, 12z) indicates the winds over the next 5 - 7 days are aligned to create a very strong Fram export.   Attached is an example for July 8th.

So this will be in addition to all of the solar insolation that is occurring.

It will be interesting to see what this collectively will do the CAB over the next 7 days.  Certainly bad for the ice, more of a question of how bad.

Summer export is very minor in comparison to the current melting processes going on. Freely mobile ice is only moving at 2% of the speed of the wind pushing it.

https://nsidc.org/cryosphere/seaice/processes/dynamics.html

My guess is that this export event might take an extra 15-20 km3 off the eventual minimum in a week. Relative to ~ 4,000 - 4,500 km3 minimum, it's not a big deal.

GoSouthYoungins

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Re: The 2020 melting season
« Reply #2123 on: July 03, 2020, 06:59:00 PM »
I respect the similarities between the extents of 2014 and 2020, but I think they are otherwise DRASTICALLY different.

The ice in 2014 was mostly white. The ice in 2020 is mostly blueing/greying. This is paramount.
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gandul

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Re: The 2020 melting season
« Reply #2124 on: July 03, 2020, 07:07:41 PM »
I respect the similarities between the extents of 2014 and 2020, but I think they are otherwise DRASTICALLY different.

The ice in 2014 was mostly white. The ice in 2020 is mostly blueing/greying. This is paramount.
Exactly, and I remember it was not one or two days different... it was the entire season so far, different.

Niall Dollard

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Re: The 2020 melting season
« Reply #2125 on: July 03, 2020, 07:12:09 PM »
For what it's worth, Physical Science Lab (formerly ESRL) forecasts on bottom melt and top melt for 6th July (forecast issued on 1st July).

Suggests bottom melt of 2cm/day at edge and down to 1cm/day further in under the ice. The bulk of it near the Russian side. This melt rate does not change much, whatever the hour of the day.

Top melt is concentrated again on the Russian side, but some also in the southern Beaufort. 1 to 2cm per day. The melt rate waxes and wanes according to the sun's elevation.

I have no idea how these melt rate forecasts compare with actual values.

 
« Last Edit: July 03, 2020, 07:43:33 PM by Niall Dollard »

Phoenix

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Re: The 2020 melting season
« Reply #2126 on: July 03, 2020, 07:27:40 PM »
For what it's worth, Physical Science Lab (formerly ESRL) forecasts on bottom melt and top melt for 6th July (forecast issued on 1st July).

Suggests bottom melt of 2cm/day at edge and down to 1cm/day further in under the ice. The bulk of it near the Russian side. This melt rate does not change much, whatever the hour of the day.

Top melt is concentrated again on the Russian side, but some also in the southern Beaufort. 1 to 2cm per day. The melt rate waxes and wanes according to the suns elevation.

I have no idea how these melt rate forecasts compare with actual values.

Very interesting charts, Niall. The bottom melt being skewed toward the periphery makes perfect sense. EMR is easily penetrating the thin ice at the edge.

I think some people will take issue with a forecast that shows large parts of the CAB with no top melt during sunny weather at peak insolation.

Can you share a link to these forecasts? I'd be interested in checking them out.

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Re: The 2020 melting season
« Reply #2127 on: July 03, 2020, 07:38:22 PM »

I think some people will take issue with a forecast that shows large parts of the CAB with no top melt during sunny weather at peak insolation.

Yes, the camera at the North Pole often showed melting ponds.



Example

http://nsidc.org/arcticseaicenews/2013/08/

http://nsidc.org/arcticseaicenews/files/2013/08/Figure41-350x371.png

Quote
Figure 4. These comparison images show the North Pole Web Cam on July 25, 2013 (top), and July 30, 2013 (bottom).

Quote
First, the webcam is not at the North Pole. Because of the drift of the ice, as of this week it is actually located at about 84 degrees North near the prime meridian. Second, the so-called lake is nothing more than a large summer melt pond atop the ice cover, and is not, as some have said, a hole or a polynya in the ice cover. While quite extensive by July 26, the pond appears to have largely disappeared by July 30, by draining off the sea perhaps through a fracture, followed by a dusting of snow.

Can you share a link to these forecasts? I'd be interested in checking them out.

https://psl.noaa.gov/forecasts/seaice/

Snow Ice -> Ice Melt Terms

Pagophilus

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Re: The 2020 melting season
« Reply #2128 on: July 03, 2020, 07:40:07 PM »
Siberian sea ice extent in June, year on year.  As with the other graph Arctic Melt posted for decline in Siberian ice this year, this trend that has got more than a hint of exponential character to it, at least when viewed from this year's perspective.  https://twitter.com/ZLabe/status/1278691513795375104/photo/1   Graph originates from NSIDC.
« Last Edit: July 03, 2020, 07:51:51 PM by Pagophilus »
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Phoenix

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Re: The 2020 melting season
« Reply #2129 on: July 03, 2020, 07:50:25 PM »

Can you share a link to these forecasts? I'd be interested in checking them out.

https://psl.noaa.gov/forecasts/seaice/

Snow Ice -> Ice Melt Terms

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Re: The 2020 melting season
« Reply #2130 on: July 03, 2020, 07:53:03 PM »
For what it's worth, Physical Science Lab (formerly ESRL) forecasts on bottom melt and top melt for 6th July (forecast issued on 1st July).

Suggests bottom melt of 2cm/day at edge and down to 1cm/day further in under the ice. The bulk of it near the Russian side. This melt rate does not change much, whatever the hour of the day.

Top melt is concentrated again on the Russian side, but some also in the southern Beaufort. 1 to 2cm per day. The melt rate waxes and wanes according to the suns elevation.

I have no idea how these melt rate forecasts compare with actual values.

Very interesting charts, Niall. The bottom melt being skewed toward the periphery makes perfect sense. EMR is easily penetrating the thin ice at the edge.

I think some people will take issue with a forecast that shows large parts of the CAB with no top melt during sunny weather at peak insolation.

Can you share a link to these forecasts? I'd be interested in checking them out.

Yes, there's *clearly* considerable top melt on Worldview (both on band sets 7-2-1 and 3-6-7 on MODIS) and is even obvious through true color visible as widespread darkening and blue coloration. There's enough rapid melt that there's been some *brightening* in parts of the Laptev front as pond drainage occurs over the past 2 days.

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Re: The 2020 melting season
« Reply #2131 on: July 03, 2020, 08:05:17 PM »
I respect the similarities between the extents of 2014 and 2020, but I think they are otherwise DRASTICALLY different.

The ice in 2014 was mostly white. The ice in 2020 is mostly blueing/greying. This is paramount.

You may well be right, GoSouth, but please note your locator map (with the red square) is from a later stage in the melting season, so that threw me a bit.   It is always a bit tricky gauging differences in colors of ice, and particularly for the Arctic as a whole, so I wondered if Tealight's Albedo Warming Potential data (which I have just been introduced to myself) might not provide a better Arctic-wide picture of this issue.  So I went to the site, but there were no graphs comparing 2014 to 2020.  There is no doubt from those graphs, however, that 2020 is up there in terms of low albedo.
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Re: The 2020 melting season
« Reply #2132 on: July 03, 2020, 08:06:43 PM »
Ice colouring blue/grey as far north as 87.5.

Only other year that had almost as far north colour change this early was...2012.

Edit: Image is from July 3
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Re: The 2020 melting season
« Reply #2133 on: July 03, 2020, 08:26:06 PM »
Ice colouring blue/grey as far north as 87.5.

Only other year that had almost as far north colour change this early was...2012.

Edit: Image is from July 3

Perhaps further than that as the cutoff in visible is due to advection fog and low stratus. The widespread advection fog event over the past 2-3 days did a big number on the pack up there.

Roll back to the 29th on that sector and you'll see there's still some snow cover. The warm front (and associated advection fog) rolls in right afterwards and destroys virtually all of it, leaving behind ponded bare ice. Strong subsidence from the building ridge moves in right after that, clearing out even the low clouds and exposing it to full sun.

I've seen deep snowpacks virtually obliterated overnight by strong WAA and advection fog events. It generally takes very warm air aloft and dewpoints above freezing to do it. The combination of direct heat exchange and direct diabatic heat release from condensation of water vapor directly onto the snowpack has a devastating effect.

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Re: The 2020 melting season
« Reply #2134 on: July 03, 2020, 08:30:58 PM »
Quote from: ArcticMelt2
<snippage>
...But yesterday, all the same, doubts arose that the 2012 record would be broken. On the second place by the minimum ice extent in the Laptev Sea on July 1, not 2012, 2014 (data NSDIC extent):
<snippage>
...So fortunately, the 2012 record this year is not in danger. Most likely the forecast according to SMOS for June is the most accurate....
<snippage>

What will determine the outcome is the weather, not the current state of the ice.  That was true in 2012.  It was true in 2013 and 2014, both of which had ice as vulnerable as we see now, but were saved by the weather.  2013's weather in particular was down-right *weird*.

Application of statistics to relatively short term historical information will be about as useful as trying to apply those same methods to stock prices.  The irony is your choice of 2014 is in a way exemplary of that.

The 2012 record is absolutely in play right now, by way of the current weather conditions, and the preconditioning that's taken place over the last 8 weeks.

For the ice to be saved, this weather we see *currently* needs to break, and break hard in favor of the ice.  The forecasts are not optimistic in this regard.
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Re: The 2020 melting season
« Reply #2135 on: July 03, 2020, 08:50:07 PM »
Quote from: ArcticMelt2
<snippage>
...But yesterday, all the same, doubts arose that the 2012 record would be broken. On the second place by the minimum ice extent in the Laptev Sea on July 1, not 2012, 2014 (data NSDIC extent):
<snippage>
...So fortunately, the 2012 record this year is not in danger. Most likely the forecast according to SMOS for June is the most accurate....
<snippage>

What will determine the outcome is the weather, not the current state of the ice.  That was true in 2012.  It was true in 2013 and 2014, both of which had ice as vulnerable as we see now, but were saved by the weather.  2013's weather in particular was down-right *weird*.

Application of statistics to relatively short term historical information will be about as useful as trying to apply those same methods to stock prices.  The irony is your choice of 2014 is in a way exemplary of that.

The 2012 record is absolutely in play right now, by way of the current weather conditions, and the preconditioning that's taken place over the last 8 weeks.

For the ice to be saved, this weather we see *currently* needs to break, and break hard in favor of the ice.  The forecasts are not optimistic in this regard.

Yeah, not really seeing the comparison to 2014. While 2014 had some hostile weather for ice on the Russian side, it can't hold a candle to this year -- which started melting under that big honking dipole in *mid-May*. Widespread ponding was already starting by the end of May on the fast ice and now there isn't all that much left. The Laptev Bite is certainly bigger this year (if oriented differently).

It could legitimately make a run at the pole this year.

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Re: The 2020 melting season
« Reply #2136 on: July 03, 2020, 09:12:50 PM »
It is also interesting that the minimum ice extent a in the Laptev Sea falls in 2014 (data NSDIC extent).

1. 2014    887 km2
2. 2018   9031 km2
3. 2013  11830 km2
4. 2011  14157 km2
5. 2012  21509 km2

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Re: The 2020 melting season
« Reply #2137 on: July 03, 2020, 09:21:08 PM »
Thank you gerontocrat for your reply and charts. I wanted a basic overview of these charts as we go through this anomalous high pressure over the basin. Sunlight/Insolation V's Compaction/Dispersion and to understand the impact for future reference.

One more, showing daily (rather than 5 day running average) values, from Nico Sun (image 1).

Also, looks like we will lose ~400,000 km2 in extent from Hudson Bay over the next ~10 days (image 2). Area has just started its steep decline (image 3).

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Re: The 2020 melting season
« Reply #2138 on: July 03, 2020, 10:22:29 PM »
For what it's worth, Physical Science Lab (formerly ESRL) forecasts on bottom melt and top melt for 6th July (forecast issued on 1st July).

Suggests bottom melt of 2cm/day at edge and down to 1cm/day further in under the ice. The bulk of it near the Russian side. This melt rate does not change much, whatever the hour of the day.

Top melt is concentrated again on the Russian side, but some also in the southern Beaufort. 1 to 2cm per day. The melt rate waxes and wanes according to the sun's elevation.

I have no idea how these melt rate forecasts compare with actual values.

Those are compete junk.

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Re: The 2020 melting season
« Reply #2139 on: July 03, 2020, 10:37:15 PM »
Area anomaly. Useful map that for some reason isn't posted very often.
Thank you.  As a map fiend I really like this.  Maybe it would be used more if the baseline for comparison were not 1979 to 2015 and instead were a more recent set of years??  As it is, I think it shows how different this year is with much clarity.
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Re: The 2020 melting season
« Reply #2140 on: July 03, 2020, 10:41:31 PM »
Area anomaly. Useful map that for some reason isn't posted very often.
Thank you.  As a map fiend I really like this.  Maybe it would be used more if the baseline for comparison were not 1979 to 2015 and instead were a more recent set of years??  As it is, I think it shows how different this year is with much clarity.

It is a more recent set of years. 2000-2019 according to the text on the image itself. Or was that what you meant?

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Re: The 2020 melting season
« Reply #2141 on: July 03, 2020, 10:43:38 PM »
Last 24 Hours + Five Day Forecast
Wind @ Surface

This Giant AntiCyclone is gorgeous. I've added the last 24 hours as well this time so you could see the destruction that has already happened in the ESS.

Fram export will be brutal if the whole thing starts spinning.
Not just Fram, where the effect will certainly be very bad. It seems a strong wind will also blow down Nares Strait, where the Kane Basin arch is already broken and the ice is mostly mobile. This wind should clear the strait of most of its current ice and open the floodgates to Lincoln Sea export.
There will also be a period of strong wind down the southeastern part of the main CAA channel. I don't expect serious effects on the (still) stable fast ice, but that is another area to watch.

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Re: The 2020 melting season
« Reply #2142 on: July 03, 2020, 10:49:54 PM »
'Streamers' of melting ice developing enthusiastically on the edge of the icecap in the western Laptev.   

Worldview, July 3.  Unaltered.
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Re: The 2020 melting season
« Reply #2143 on: July 03, 2020, 10:52:37 PM »
Area anomaly. Useful map that for some reason isn't posted very often.
Thank you.  As a map fiend I really like this.  Maybe it would be used more if the baseline for comparison were not 1979 to 2015 and instead were a more recent set of years??  As it is, I think it shows how different this year is with much clarity.

It is a more recent set of years. 2000-2019 according to the text on the image itself. Or was that what you meant?
I had read the NSIDC introduction pop-up box which gave me the 1979-2015 (mis)information.  Glad to know it is in fact 2000-2019... much more useful IMO.  Thanks.
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Re: The 2020 melting season
« Reply #2144 on: July 03, 2020, 10:53:53 PM »
I respect the similarities between the extents of 2014 and 2020, but I think they are otherwise DRASTICALLY different.

The ice in 2014 was mostly white. The ice in 2020 is mostly blueing/greying. This is paramount.

It is always a bit tricky gauging differences in colors of ice, and particularly for the Arctic as a whole, so I wondered if Tealight's Albedo Warming Potential data (which I have just been introduced to myself) might not provide a better Arctic-wide picture of this issue.  So I went to the site, but there were no graphs comparing 2014 to 2020.  There is no doubt from those graphs, however, that 2020 is up there in terms of low albedo.
Tealight does not assess actual ice albedo. He has a model that multiplies insolation by estimated albedo with values for open water, bare ice, and ice with snow. A great asset to have, but not something that can answer the question of ice color.
And yeah all his site uses the baseline since 2000. This was something he discussed here when setting up the site.

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Re: The 2020 melting season
« Reply #2145 on: July 03, 2020, 11:08:41 PM »
I respect the similarities between the extents of 2014 and 2020, but I think they are otherwise DRASTICALLY different.

The ice in 2014 was mostly white. The ice in 2020 is mostly blueing/greying. This is paramount.

It is always a bit tricky gauging differences in colors of ice, and particularly for the Arctic as a whole, so I wondered if Tealight's Albedo Warming Potential data (which I have just been introduced to myself) might not provide a better Arctic-wide picture of this issue.  So I went to the site, but there were no graphs comparing 2014 to 2020.  There is no doubt from those graphs, however, that 2020 is up there in terms of low albedo.
Tealight does not assess actual ice albedo. He has a model that multiplies insolation by estimated albedo with values for open water, bare ice, and ice with snow. A great asset to have, but not something that can answer the question of ice color.
And yeah all his site uses the baseline since 2000. This was something he discussed here when setting up the site.
Thank you, oren.  And Tealight.  (Note to self -- lots to learn).   Is there a way in which Arctic sea ice albedo is quantitatively measured/assessed over time?  Or are the measurements too difficult to take given constant atmospheric changes (clouds, haze etc)? 
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Re: The 2020 melting season
« Reply #2146 on: July 03, 2020, 11:12:13 PM »
The comparison to 2014 is RIDICULOUS.

JUNE OF 2014 was a o MONTH of cool air ADVECTION, wide spread cloud canopy's, and WIDESPREAD DENSE FOG!

 the two graphics below show 2014 being below normal versus 2020 being one of the warmest June's on record and the warmest MAY on record
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Re: The 2020 melting season
« Reply #2147 on: July 03, 2020, 11:51:36 PM »
Last 24 Hours + Five Day Forecast
Wind @ Surface

This Giant AntiCyclone is gorgeous. I've added the last 24 hours as well this time so you could see the destruction that has already happened in the ESS.

Fram export will be brutal if the whole thing starts spinning.
Not just Fram, where the effect will certainly be very bad. It seems a strong wind will also blow down Nares Strait, where the Kane Basin arch is already broken and the ice is mostly mobile. This wind should clear the strait of most of its current ice and open the floodgates to Lincoln Sea export.
There will also be a period of strong wind down the southeastern part of the main CAA channel. I don't expect serious effects on the (still) stable fast ice, but that is another area to watch.
You're right Oren, Nares Strait will get its pipes cleaned so to say. What I'm curious for is how much the Mega crack will open up as the ice compacts due to this Huge AntiCyclone, and how much of that thick ice will be transported towards the beaufort.

One good outcome is that it'll be tough to melt out the beaufort this season if it's gonna get all that thick ice added to it. The Beaufort might save the season, unless my theory of strong bottom melt turns out to be true of course. But we'll know more about that later in the season.

One thing is for sure, Woody will lose what's left of his legs through Fram. I'm curious to see if he can keep some of his body...


Don't take this graphic all too serious. It still has ice in the Kara, but I keep watching it to follow trend.
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Re: The 2020 melting season
« Reply #2148 on: July 04, 2020, 12:04:19 AM »
Worldview showing a lot of dispersion in the ESS between yesterday (July 2nd) and today. The ice is moving towards the Laptev, which seems like it should speed up melting.

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Re: The 2020 melting season
« Reply #2149 on: July 04, 2020, 12:05:12 AM »
Interesting.