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binntho

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Re: The 2020 melting season
« Reply #1000 on: May 22, 2020, 12:51:45 PM »
there is a torrid downslope coming to the Beaufort.
<snip>
Assuming heights and winds come as forecasted the factor deciding how things will play out is how much sun will be accompanying the WAA downslope.

Friv, I am very grateful for how much more work you are putting into explaining things to us footlings trying to follow your soaring flight.

But I'm still at loss sometimes. What is a downslope, and what do you mean by "WAA"?
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SimonF92

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Re: The 2020 melting season
« Reply #1001 on: May 22, 2020, 12:53:22 PM »

We don't know what is going to happen in June but so far we are likely going into June in best modern set up to ravage the inner Arctic basin.

I guess that's a matter of opinion. 2012 and 2016 had very weak freezing seasons which preceded them and set the stage with thinner ice. By comparison, 2020 was a much better freezing season. Hoping for a mid-May PIOMAS volume update which gives us a better idea of thickness.

2012 and 2016 were middle of the pack in terms of their freezing seasons. 2014, 2017, 2018 were just as bad
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Frivolousz21

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Re: The 2020 melting season
« Reply #1002 on: May 22, 2020, 01:00:42 PM »

We don't know what is going to happen in June but so far we are likely going into June in best modern set up to ravage the inner Arctic basin.

I guess that's a matter of opinion. 2012 and 2016 had very weak freezing seasons which preceded them and set the stage with thinner ice. By comparison, 2020 was a much better freezing season. Hoping for a mid-May PIOMAS volume update which gives us a better idea of thickness.

That isn't what we use to define a melting season.

Everyone agrees that 2007 was the melt season on record.

Because the conditions for melt June-Aug were amazing.

If we had an exact repeat of 2007 weather wise we would crush 2012 lows.

The preconditioning that has taken place and is still to come taking place is putting 2020 in one of the best spots  going into June in modern times.

2020 having slightly more ice thickness means nothing if we have melt weather going into June.




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Frivolousz21

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Re: The 2020 melting season
« Reply #1003 on: May 22, 2020, 01:08:01 PM »
there is a torrid downslope coming to the Beaufort.
<snip>
Assuming heights and winds come as forecasted the factor deciding how things will play out is how much sun will be accompanying the WAA downslope.

Friv, I am very grateful for how much more work you are putting into explaining things to us footlings trying to follow your soaring flight.

But I'm still at loss sometimes. What is a downslope, and what do you mean by "WAA"?

Thank You!

Downslope is the winds coming down from a higher elevation to a lower.

This is what Google says.

Downsloping is the process that occurs when a stream of air is forced to descend a mountain. As the air descends, it undergoes a series of changes that result in a warming/drying effect. This series of changes is known as adiabatic warming. So what does that mean?Dec 29, 2018



WAA stands for WARM AIR ADVECTION.
simple meaning for warm air advection is warm air moving into an area replacing the previous cooler air mass.

As the forecast gets going the winds blow down off the mountains and warn and dry out.

Bringing WAA to the Arctic basin
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Niall Dollard

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Re: The 2020 melting season
« Reply #1004 on: May 22, 2020, 01:26:55 PM »
Here's one for you Friv.

Khatanga, Russia at 72 North was an incredible 25.4 C at 9Z today.

Going by our usual Russian source it looks like it shattered the date record and the May record there.

and the max maybe even higher than I've shown here.
« Last Edit: May 22, 2020, 01:33:03 PM by Niall Dollard »

binntho

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Re: The 2020 melting season
« Reply #1005 on: May 22, 2020, 01:32:59 PM »
Ok, thanks, I thought that "downslope" was some mystical meteorological moniker, not simply "down the mountain slope".

Acronyms can be tricky - the following is a list of the most common definitions of WAA:
Weird and Awkward
Wales, Alaska
World A Capella Association

with "Warm Air Advection" being the only meteorological one, so I should have been able to figure that out myself.  :-[
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Phoenix

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Re: The 2020 melting season
« Reply #1006 on: May 22, 2020, 01:41:25 PM »

We don't know what is going to happen in June but so far we are likely going into June in best modern set up to ravage the inner Arctic basin.

I guess that's a matter of opinion. 2012 and 2016 had very weak freezing seasons which preceded them and set the stage with thinner ice. By comparison, 2020 was a much better freezing season. Hoping for a mid-May PIOMAS volume update which gives us a better idea of thickness.

That isn't what we use to define a melting season.

Everyone agrees that 2007 was the melt season on record.

Because the conditions for melt June-Aug were amazing.

If we had an exact repeat of 2007 weather wise we would crush 2012 lows.

The preconditioning that has taken place and is still to come taking place is putting 2020 in one of the best spots  going into June in modern times.

2020 having slightly more ice thickness means nothing if we have melt weather going into June.

IMO, thickness is an important reflection of a preconditioning process which begins long before the melt season begins.

The CAB is the reservoir of most of the season ending ice. At 4/30/2020, PIOMAS was indicating ~ 500 km3 more ice in the CAB vs. 2019 and ~1,300 km3 more vs. 2017.  The Beaufort also was running a few hundred km3 above those years. You might characterize these as "slight" differences. I don't.

When faced with the prospect of cutting down a tree and a limited time frame to do, the thickness of the tree and the amount of time remaining to cut it down matter. 

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Re: The 2020 melting season
« Reply #1007 on: May 22, 2020, 02:54:38 PM »
Re: WAA. I had to look it up recently and found it on this site at the "Glossary.. for Newbies and Others" which has a very helpful list of acronyms. Thanks to everyone for the very interesting discussion, and Friv for the "downsloping" tutorial. I wish I knew more meteorology. Many of the graphs leave me completely bewildered.

ArcticMelt2

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Re: The 2020 melting season
« Reply #1008 on: May 22, 2020, 02:59:08 PM »
Here's one for you Friv.

Khatanga, Russia at 72 North was an incredible 25.4 C at 9Z today.

Going by our usual Russian source it looks like it shattered the date record and the May record there.

and the max maybe even higher than I've shown here.


Exceeding century records at once by 5 degrees is similar to the effect of a sharp drop in the content of aerosols in the atmosphere.

oren

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Re: The 2020 melting season
« Reply #1009 on: May 22, 2020, 04:00:07 PM »
The CAB is the reservoir of most of the season ending ice. At 4/30/2020, PIOMAS was indicating ~ 500 km3 more ice in the CAB vs. 2019 and ~1,300 km3 more vs. 2017.  The Beaufort also was running a few hundred km3 above those years. You might characterize these as "slight" differences. I don't.
The well-placed extra volume in the Beaufort could well have a significant impact on the melting season. 2016 was quite delayed by very thick ice in the Beaufort ("Big Block"). However, looking at the placement of the extra volume in the CAB during April does not inspire much confidence, especially as May saw a very strong export event right from the anomalous region and into the Fram. Certainly the upcoming PIOMAS update will be very interesting.

Phoenix

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Re: The 2020 melting season
« Reply #1010 on: May 22, 2020, 05:44:59 PM »
The CAB is the reservoir of most of the season ending ice. At 4/30/2020, PIOMAS was indicating ~ 500 km3 more ice in the CAB vs. 2019 and ~1,300 km3 more vs. 2017.  The Beaufort also was running a few hundred km3 above those years. You might characterize these as "slight" differences. I don't.
The well-placed extra volume in the Beaufort could well have a significant impact on the melting season. 2016 was quite delayed by very thick ice in the Beaufort ("Big Block"). However, looking at the placement of the extra volume in the CAB during April does not inspire much confidence, especially as May saw a very strong export event right from the anomalous region and into the Fram. Certainly the upcoming PIOMAS update will be very interesting.

That's a very interesting image Oren, in that is quite detailed in locating anomalies from the 2010-2018 average. It has some new information for me.

My interpretation of the image is a little different than yours, in part because I begin with a different frame of reference. For one, I begin with a more simplistic reference point of a single year (2019) to try and envision the comparative outlook for 2020.

At the 2019 minimum, over 90% of the ice is in the deep CAB, N. Beaufort and N. CAA. I try to imagine this combined area as a fortress and evaluate 2020 in it's current position to penetrate the regions that 2019 could not.

1) Wipneus' April 2020 thickness charts show the presence of an "arm" in the Beaufort of thick ice in the 2.5m - 3.0m range which your image here seems to corroborate. His April 2019 charts show considerably less ice in the arm region. I suspect if you were to prepare an anomaly chart of 2019 vs. 2020, you would see a much different image than your comparison of 2020 vs 2010-18.

My understanding remains that the 2020 Beaufort is light years ahead of 2019 in terms of it's serving as a buffer to the fortress.

2) The highlighted areas from your image on the Atlantic side are the new information for me. It's also true that there was a substantial export interval which corresponded with an area (north of Svalbard) of high volume anomaly in the image. My interpretation of the export event is that it was significant but not a game changer for a couple of reasons.

a) The region between 80-82N on the Atlantic side is the shallow CAB. It melted out in 2019 and for comparative purposes, the baseline expectation is that it will melt out again in 2020.

b) The recent export event had a very intense peak, but was of limited duration at less than a week. Allowing for expected losses, my expectation is that there will still be above average thickness along  the Atlantic side of the CAB.

3) That leaves the Siberian side with a head start vs. 2019. I'll concede that.

I'm placing a lot of value of the cold-ish winter (vs. recent standards) and the most recently available PIOMAS data. At this point, I'm guessing we won't see a Mid-May PIOMAS update. We didn't get one last year.






igs

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Re: The 2020 melting season
« Reply #1011 on: May 22, 2020, 07:09:06 PM »

We don't know what is going to happen in June but so far we are likely going into June in best modern set up to ravage the inner Arctic basin.

I guess that's a matter of opinion. 2012 and 2016 had very weak freezing seasons which preceded them and set the stage with thinner ice. By comparison, 2020 was a much better freezing season. Hoping for a mid-May PIOMAS volume update which gives us a better idea of thickness.


You have to take his entire post to understand his point. By cherry picking the winter part and leaving out the last week's and next few day's condition is not a valid argument to make something obvious looking opinionated.


His post goes till end of may, stating that we dunno what's happening in June, means he is taking into account the winter freeze + current state + next 10 days and then it perfectly fits IMO.


BTW happens too often that someone is doing a great post and then some minor things that are not 100% on the safe side are used to discredit the entire point that has been made so well and is very much valid.

pearscot

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Re: The 2020 melting season
« Reply #1012 on: May 22, 2020, 07:14:43 PM »
I probably sound like a broken record, but I don't care. I'm just in complete awe at this season and how it has been unfolding thus far. I know it's too early to tell, but I just *feel* this year's different. Maybe it has been the subsequent years following 2012, but the number of systematic changes, feedback loops, and Atlantification has entirely changed the dynamics of the ice.

I certainly think it's possible Utqiagvik witness the earliest shoreline breakup on record and also the rapid expansion of this crack is just astonishing to me (screen cap from today). It's clear and 35f there today with the forecast outlook discussing wind/warmth in central Alaska and a large high pressure building over the arctic. It's been a rough week, and hope you all have a decent Friday as well.






pls!

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Re: The 2020 melting season
« Reply #1013 on: May 22, 2020, 07:58:00 PM »
Even if the Beaufort proves more difficult to melt out, it looks like we will get more melting from the Atlantic side this year than last year. Plus, area is already lower than 2019 and dispersion higher.

In any case, as already pointed out, Beaufort gets some sustained warmth this week, so we'll soon get some more data on how resilient the ice is there.

Paul

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Re: The 2020 melting season
« Reply #1014 on: May 22, 2020, 08:05:47 PM »
One of the reasons why 2012 went so low was down to the dispersion of the ice pack and the perfect placement of the GAC during August and in turn any warm SSTS attacked the ice on the Atlantic side of the basin as the melt season came to a close(the ice edge was getting closer to the pole).

2019 was not a disperse ice pack for the most part hence I was doubtful the record would of been broken however warm SSTs was still doing the damage to the ice hence it dropped to the 2nd lowest.

So if the ice pack during June starts to develop loads of small holes in it and SSTs are above average then a record melt could well happen. If its more compact and SSTs are not high then I will have more doubts however early open water can of course give a head start to SSTs.

Going to be an interesting few months coming up.

pauldry600

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Re: The 2020 melting season
« Reply #1015 on: May 22, 2020, 08:16:31 PM »
2012 looks an outlier still but this year looks like it will definitely be a top 3 year. Coastal ice is toasting everywhere and it's still not June.

Very interesting that ice looks so delicate everywhere so unless theres a freeze which seems unlikely we are looking at an extremely precarious looking Arctic come September.

pearscot

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Re: The 2020 melting season
« Reply #1016 on: May 22, 2020, 08:19:58 PM »
One of the reasons why 2012 went so low was down to the dispersion of the ice pack and the perfect placement of the GAC during August and in turn any warm SSTS attacked the ice on the Atlantic side of the basin as the melt season came to a close(the ice edge was getting closer to the pole).

2019 was not a disperse ice pack for the most part hence I was doubtful the record would of been broken however warm SSTs was still doing the damage to the ice hence it dropped to the 2nd lowest.

So if the ice pack during June starts to develop loads of small holes in it and SSTs are above average then a record melt could well happen. If its more compact and SSTs are not high then I will have more doubts however early open water can of course give a head start to SSTs.

Going to be an interesting few months coming up.

Yeah, I think that's a good point. For the time being, I'm not really focused on extent drops as much as I am overall thinning and more open areas appearing. While the sun's angle is not ideal for direct melting, any unimpeded sunlight directly into the ocean/seas will slowly chip away at everything that surrounds it and add more energy to the system at large. Beyond that, it looks like much of the Kara, Eastern Siberian, and Laptev Seas consist of rubble/fractured ice.

Plus, when you measure the actual gaps between the ice, some of them are 1-5 miles which is fairly significant. I know the Puget Sound (where I live) is far different, but during the summer it's surprising to see how much clear days can warm the surface water and also the wave action that can occur from 30+mph winds.
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Niall Dollard

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Re: The 2020 melting season
« Reply #1017 on: May 22, 2020, 09:17:50 PM »
Khatanga's anomalies the past 6 days have all been +10 C or more. Today 22nd May the mean was +17.8 C above normal.

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Re: The 2020 melting season
« Reply #1018 on: May 22, 2020, 10:04:03 PM »
This CAB-sized fiery anomaly will roast Khatanga 2 more days.
« Last Edit: May 22, 2020, 10:12:13 PM by Aluminium »

Paul

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Re: The 2020 melting season
« Reply #1019 on: May 22, 2020, 10:30:48 PM »
The models are forecasting more troughing and cooler temperatures eventually for parts of Siberia where it has been record breaking heat lately, just a bit too late for the snow cover there.

Next thing to watch is this dipole, as some members are saying some warmth coming into the Beaufort, nothing extraordinary mind in all fairness(compared to 2011 for example) and the winds don't look the strongest however we should see the Beaufort ice changing direction and head towards the basin and open water forming behind, maybe to some extent some compaction might not be a bad thing for the ice longer term? I do think the ice in the ESS could start to look a bit sorry for itself again though as the winds switch direction again.

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Re: The 2020 melting season
« Reply #1020 on: May 22, 2020, 10:45:33 PM »
Wasn't 2012 also the year of the weird Mackenzie Delta warm water pulse that decimated the Beuafort? Maybe my years are off but I thought that was the year that the fast ice lasted a really long time and fresh water spent a long time backed up behind the ice soaking up a lot of heat before it broke through the ice and melted out a huge amount of stuff in the Beaufort as the warm water pulsed out.

Stopped being lazy and checked and the low was heavily influenced that year because of the Mackenzie.  https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2013GL058956

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Re: The 2020 melting season
« Reply #1021 on: May 23, 2020, 12:33:55 AM »
     
Stopped being lazy and checked and the low was heavily influenced that year because of the Mackenzie.  https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2013GL058956

     I haven't given much attention to the effect of river discharge on the Arctic sea ice.  While the warm outflow of a big river seemed important for impact on the ice near the river delta, it seemed too small to matter much to the big picture, e.g. heat content of the entire Arctic Ocean, or even to the entire Beaufort Sea.  But these statements from the paper linked by Error refute that:
     "The Mackenzie and other large rivers can transport an enormous amount of heat across immense continental watersheds into the Arctic Ocean"

     "...the volume of the total discharge over the 3 week period is equivalent to a layer thickness of 0.19 m of warm waters across the entire open water area of 316,000 km2"
     (ed.  The area of the Beaufort Sea is 178,000 km2)

      "The warmest waters were observed near the coast of the Mackenzie Delta, e.g., 13°C at 147 km, 10°C at 287 km, 8°C at 350 km, and 2°C as far as 456 km from the Mackenzie River mouth"

     "The Mackenzie River has an enormous watershed of 1.8 million km2 with the southern extent reaching to 52.2oN. This watershed is primarily within the continental climate regime, and the heat can be intense in summer when the maximum temperature may reach 32°C around latitude 53°N (e.g., Edmonton, Alberta, Canada). Fresh and warm Mackenzie waters reside in the surface layer with the attendant high thermal capacity thus contributing excessive heat to melt sea ice, most effectively when the sea ice cover has been fragmented "

     "In addition to the Mackenzie, there are a number of other large rivers that discharge into the Arctic Ocean. Notable are the Yukon, Ob, Yenisei, Lena, and Kolyma Rivers, each with its immense watershed under a continental climate regime providing massive discharge of warm waters into the Arctic Ocean or a peripheral sea to melt sea ice in spring and summer. "

     "This massive discharge carries an enormous heating power of 1.0 × 1019 J/yr for each 1°C of the warm river waters above freezing, equivalent to 2.5 gigaton of trinitrotoluene (TNT) per °C per year. "

     "In the summer melt season, warm river waters, for which the temperatures can be higher than 10°C, contribute directly to melting sea ice. In the fall season around the time of sea ice freezeup, surface waters cool while the halocline stratification insulates the surface from the deeper seawater, allowing more sea ice to grow. At the same time in the fall, rivers also start to freezeup, drastically reducing the river discharge. Thus, to be an effective insulator, the stratification needs to be persistent to maintain the surface layer consisting of a large mass of fresh river waters that already discharged into the Arctic Ocean earlier in the summer. Such maintenance of the stratification requires calm‐ocean conditions without significant mixing throughout the summer to fall freezeup. In summer 2012, the violent storm significantly enhanced ocean mixing that transported ocean heat upward and further contributed to sea ice melt "
« Last Edit: May 23, 2020, 01:10:31 AM by Glen Koehler »

Phoenix

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Re: The 2020 melting season
« Reply #1022 on: May 23, 2020, 12:35:26 AM »

You have to take his entire post to understand his point. By cherry picking the winter part and leaving out the last week's and next few day's condition is not a valid argument to make something obvious looking opinionated.

His post goes till end of may, stating that we dunno what's happening in June, means he is taking into account the winter freeze + current state + next 10 days and then it perfectly fits IMO.

BTW happens too often that someone is doing a great post and then some minor things that are not 100% on the safe side are used to discredit the entire point that has been made so well and is very much valid.

Cherry picking ? The freezing season represents >= half a year of activity and the most recently concluded winter was probably the coldest in the last half decade. Assessing the condition of ice on 6/1 based only on what happens in May and disregarding what happened from Dec through April seems closer to cherry picking to me.

If someone wanted to go into the lab and design a perfect storm to result in a record low minimum, I'm pretty sure they wouldn't start the melt season beginning with thicker ice in the areas most likely to retain ice at the minimum.

Frivolousz21

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Re: The 2020 melting season
« Reply #1023 on: May 23, 2020, 12:57:06 AM »
It being extra cold means almost nothing.

The ice can only grow so much regardless of the temperature variance we see in the Arctic.

Looking at these two cryosat thickness images from 2019 and 2020.

I'd say the 2020 shows a thinner area of first year ice.

I suppose the 2019 image is for April while the 2020 image is part of March and April.

Either way the is no discernable difference .  That's why the winter period is being dismissed.

The only factor that would have a major impact is snow depth on the ice.

Which there hasn't been any evidence to show that as an something above normal.

The top image is 2019 the bottom 2020.

Outside of the MYI.  The FYI and 2YI in 2019 is actually thicker in a lot of places.

The 2020 image ends on April 6th.

I believe the 2019 image ends on the 20th so the 2020 image would gain some thickness beyond that I'm a direct comparison.

But this is the reason most people here don't put much stock in the winter temperatures.

« Last Edit: May 23, 2020, 01:06:00 AM by Frivolousz21 »
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Re: The 2020 melting season
« Reply #1024 on: May 23, 2020, 01:27:03 AM »
Snow cover in the asian side is so low... and ice along the ESS Laptev and Kara coasts shows a pretty bad state already.

The American side however is a bit later in snow melt than last year.
Weather forecast shows warming of Beaufort sea area and winds that will pull the ice away from the coast in the next few days. Kara will continue towards a possible record early ice loss this year.

Are we gonna have the persistently warm June-July of last year or the cloudy mixed weather of prior years since 2012? Although 2016 was a warm season in disguise...

Phoenix

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Re: The 2020 melting season
« Reply #1025 on: May 23, 2020, 01:48:00 AM »
It being extra cold means almost nothing. The ice can only grow so much regardless of the temperature variance we see in the Arctic.

(snip)

But this is the reason most people here don't put much stock in the winter temperatures.
I think you should speak for yourself Friv and not try to bully by asserting what other people think.

It might be interesting to take a poll of ASIF users and see which percentage of them don't see a relationship between winter temperatures and ice thickness. Also interesting to wonder why someone like Nico Sun places so much emphasis on the metric of Freezing Degree Days. Seems like you're indicating that's all nonsense.

I value the 3D measures of the Arctic and I appreciate the efforts of the people at UW and respect users like Wipneus, Gerontocrat, Oren and Neven who have brought info and analysis to the PIOMAS volume thread. You may not consider that PIOMAS data relevant to interpreting the current state of the Arctic, but I do.

I would be fascinated to read your interpretation of the factors which determine winter sea ice thickness in which temperature is not an important attribute.


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Re: The 2020 melting season
« Reply #1026 on: May 23, 2020, 05:47:02 AM »
Ice thickness is virtually tied with last year at this time and a bunch of other years in the last decade or so.

There is nothing else to say about this.   There is absolutely nothing showing that last winter had some special impact more than any other recent winter.

I don't even understand what the argument is at this point.

And there is certainly no bullying going on here.
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binntho

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Re: The 2020 melting season
« Reply #1027 on: May 23, 2020, 05:59:50 AM »
I would be fascinated to read your interpretation of the factors which determine winter sea ice thickness in which temperature is not an important attribute.

I wont presume to answer for Friv, but speaking for my self, I think that I can easily see a situtation where winter A has lower air temperatures than winter B, but winter B ends up with thicker ice than winter A.

Difference in Fram export is perhaps the most obvious method of ending up with thinner ice in spite of lower temperatures, and ice motion in general is an important factor in determining thickness, and the temperature of the surface waters at the start of the freezing season should also be considered.

The rate of thickening slows down significantly with increased thickness. If there were no winds, waves or currents in the Arctic, and sea surface temperatures were the same going into the freezing season, thickness would be strongly correlated to air temperatues, but even a significant difference in temperatures would only result in a small difference in thickness.

If one year had higher SSTs going into the freezing season, some of the excess heat can presumably be trapped under the newly formed ice, thus hampering the rate of thickening, resulting in thinner first-year ice in spite of lower air temperatures.

And since compaction is the main source of thick multiyear ice, and compaction results not only from movement but also resistance to movement, changes in mobility in general, and direction of movement over time, could make a big difference to how thick the ice ends up being.

And I must agree with Friv, I don't see any bullying.
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Phoenix

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Re: The 2020 melting season
« Reply #1028 on: May 23, 2020, 06:42:29 AM »
Ice thickness is virtually tied with last year at this time and a bunch of other years in the last decade or so.

There is nothing else to say about this.   There is absolutely nothing showing that last winter had some special impact more than any other recent winter.

I don't even understand what the argument is at this point.

And there is certainly no bullying going on here.


Aggregate (pan-Arctic) thickness may be similar between 2019 and 2020. I'm making the argument for thicker ice specifically in the regions where ice is most likely to remain at year end as part of a larger argument that the degree of difficulty in establishing a low minimum in 2020.

Is there more ice in the Beaufort and CAB in 2020 than 2019 at this point in time? Yes.

Are the Beaufort and CAB buffers to melting CAA ice? Yes.

Will the Beaufort, CAB and CAA have >= 90% of the ice at the minimum? Almost certainly.

Your assertion that there is nothing to substantiate the thicker ice in the CAB is wrong. A quick look at the DMI 80 temperature charts from 2016 through 2020 will show that this was the coldest winter in the last five. The 2020 PIOMAS thread volume and thickness charts support this.

Your assertion that winter temperature is not relevant to spring ice thickness is just flat out comical. As Binntho points out, temperature isn't the only variable, but it is the dominant variable.

peterlvmeng

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Re: The 2020 melting season
« Reply #1029 on: May 23, 2020, 06:52:23 AM »
The arctic temperature this year is very interesting. It shows that the air temperature is almost above normal since April. The AO shows a gradually decrease downturn. That indicates the cold air tend to stay in the polar region while mid-latitude temperature increases a lot. Every step of polar air temperature increasing is just the result of mid-latitude expanding their warm region. Unlike previous year, the high pressure ridge could aggressively intrude into the polar region for a long time in winter and spring. I am afraid this may be attributed to the upcoming La Nina. The warm water moving north. The relatively large sea ice extent helps to enhance the ocean surface current exchange with deep water in winter and spring. The effect of ocean current both in Atlantic and Pacific side will pump more water into the polar region.
« Last Edit: May 23, 2020, 06:57:30 AM by peterlvmeng »

peterlvmeng

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Re: The 2020 melting season
« Reply #1030 on: May 23, 2020, 06:58:37 AM »
La Nina is ongoing.

wdmn

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Re: The 2020 melting season
« Reply #1031 on: May 23, 2020, 07:02:16 AM »
No one is denying the importance of volume. What is being questioned are the conclusions. When it comes to arctic temps, really cold temperatures make more of a difference for extent growth, as we saw this winter. The CAA has not been a heavy melt area for some time, and is unlikely to be a determining factor. The CAB will be exposed from the Russian side this year and from the Atlantic (where it was not last year).

As for the Beaufort, it remains to be seen how much of a buffer it will provide, but I expect to see some significant melting over the next week, as many have stated already.

Along with volume are other important factors like movement of the pack, since thickening can be balanced by movement into more vulnerable areas (this is part of Pearscot's point as I understand it).

edit: extent is now second lowest, and I see no reason it cannot overtake 2016 by the end of the month.

wdmn

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Re: The 2020 melting season
« Reply #1032 on: May 23, 2020, 07:07:30 AM »
Limitations of this measure acknowledged, Beaufort is not looking great.

binntho

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Re: The 2020 melting season
« Reply #1033 on: May 23, 2020, 07:09:44 AM »
La Nina is ongoing.
Being somewhat taken back by this statement (beliveng that we were currently in a neutral, even slightly positive, state), I had a quick look at the NOAA weekly analysis and was actually more surprised to see that according to them there is an ongoing El Nino! Not a very vigorous one, it must be admitted, but still, the index for the last 5 months has been at 0.5, rising to 0.6 one month, and one actually has to go back to spring 2018 to find a negative index.

Further, NOAA predicts an ever so slight change of a La Nina by fall 2020, although some predictions are much more definite, and your image does tend to support those who see a La Nina looming on the near horizon.

But an ongoing La Nina at this time? NOAA doesn't think so.
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Re: The 2020 melting season
« Reply #1034 on: May 23, 2020, 07:36:46 AM »
Regarding volume, this year has actually been following 2012 extremely colosely. January had 2012 with slightly more volume than 2020, but February and March had them neck and neck, with April again being slightly in favour of 2012. It's going to be interesting to see what May looks like!

Check out Wipneus' graph.
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SteveMDFP

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Re: The 2020 melting season
« Reply #1035 on: May 23, 2020, 07:57:55 AM »
..
     I haven't given much attention to the effect of river discharge on the Arctic sea ice.  While the warm outflow of a big river seemed important for impact on the ice near the river delta, it seemed too small to matter much to the big picture, e.g. heat content of the entire Arctic Ocean, or even to the entire Beaufort Sea.  But these statements from the paper linked by Error refute that:
     "The Mackenzie and other large rivers can transport an enormous amount of heat across immense continental watersheds into the Arctic Ocean"

     "...the volume of the total discharge over the 3 week period is equivalent to a layer thickness of 0.19 m of warm waters across the entire open water area of 316,000 km2"
     (ed.  The area of the Beaufort Sea is 178,000 km2)

      "The warmest waters were observed near the coast of the Mackenzie Delta, e.g., 13°C at 147 km, 10°C at 287 km, 8°C at 350 km, and 2°C as far as 456 km from the Mackenzie River mouth"

     "The Mackenzie River has an enormous watershed of 1.8 million km2 with the southern extent reaching to 52.2oN. This watershed is primarily within the continental climate regime, and the heat can be intense in summer when the maximum temperature may reach 32°C around latitude 53°N (e.g., Edmonton, Alberta, Canada). Fresh and warm Mackenzie waters reside in the surface layer with the attendant high thermal capacity thus contributing excessive heat to melt sea ice, most effectively when the sea ice cover has been fragmented "

     "In addition to the Mackenzie, there are a number of other large rivers that discharge into the Arctic Ocean. Notable are the Yukon, Ob, Yenisei, Lena, and Kolyma Rivers, each with its immense watershed under a continental climate regime providing massive discharge of warm waters into the Arctic Ocean or a peripheral sea to melt sea ice in spring and summer. "

     "This massive discharge carries an enormous heating power of 1.0 × 1019 J/yr for each 1°C of the warm river waters above freezing, equivalent to 2.5 gigaton of trinitrotoluene (TNT) per °C per year...

Thanks for this.  I remember that remarkable anomaly near the mouth of the Mackenzie in 2012.  This year may shape up to show similar anomalies at that or the Siberian rivers.

El Cid

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Re: The 2020 melting season
« Reply #1036 on: May 23, 2020, 11:00:41 AM »
If river heatflow input is such a significant factort, then this year's lack of snow and warmth in Siberia is all the more important as it should mean that those huge Russian (Yenisey, Ob, Irtis, Lena) rivers will bring warmer than usual water on the Siberian side...just thinking loudly.

oren

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Re: The 2020 melting season
« Reply #1037 on: May 23, 2020, 11:47:29 AM »
Very interesting discussions going on here, and very relevant to the upcoming season.
Just please do not slip into a flame war, no one is cherry picking or bullying. There is also no need to be defensive of one's theories and expectations, as I said already the Arctic can fend for itself.
I remind that more detailed discussions can be had in other threads. Do we have a La Nina or El Nino? There's an 2020 ENSO thread. Status of Arctic rivers can be discussed in detail in the "River ice and discharge" thread.
Effects on the melting season are of course welcome here. I recall 2016's "melting success" was explained in part by the monster El Nino that year, but as far as I can tell neither La Nina nor El Nino have a direct predictable effect on sea ice.
Regarding rivers, I wonder if there is near-delta water temp data (and anomaly) for the various Arctic rivers, besides discharge data.
As for thickness/volume/winter temps, this is an unresolved question. I once tried to correlate regional PIOMAS thickness/volume at certain times with resulting sea ice area at later times of the season for the same regions, and surprising could not find much predictability there. It doesn't mean there isn't a correlation, just that I could not find it with my limited analysis.
I remind that the DMI N of 80 is a misleading chart, due to its peculiar weighting method. Each latitude slice gets the same weight, despite 80-81 being 60 times larger than 89-90. This means the DMI measure is heavily skewed towards the North Pole, and does not tell the whole story regarding the High Arctic in general, some of which is down even to 70deg in the Beaufort-Chukchi-ESS region.  FDDs are another interesting approximation but with its own limitations. PIOMAS does a much more detailed job of calculating energy transfers and ice movements, but it's not the holy grail, it has limited resolution and suffers from inherent data limitations. Cryosat and SMOS measure the ice directly, but with their own known limitations. Snow thickness is the biggest unknown for all of these methods.
This year was colder near the Pole as shown by DMI, but also had a lot of ice movement from that location both to the FJL-Svalbard region and into the Fram. So this may have reduced or negated the advantage of low winter temps.
I think it is quite safe to say that Beaufort ice is indeed thicker this year, and is also starting its movement and breakup (with the resulting area loss) rather late compared to the leading years. This could indeed have a strong effect later on. The other volume anomaly near Svalbard seems doomed, at least as of a month ago and given what we know has happened since then. Of course, there is no telling what will happen from here on.
I think it is also safe to say that summer variability in the Arctic - albedo preconditioning, temperatures, cloudiness, export - is much higher than winter variability, partly because of the diminishing returns of cold temps on further ice thickening. Thus a strong melting weather like 2007 and 2012, or a weak season like 2013 and 2014, makes much more of a difference than the wintertime effects. To wit, both 2013 and 2017 started the year with unprecedented low volume, but ended up with much higher ice than expected.
So it is obvious the season is still side open, with the ice enjoying some strengths and some weaknesses. Of these, the early preconditioning and the Beaufort "fortress" seem to be very important factors, but which of them will prevail depends on June and July.

Note: the source of "my" thickness maps is the PIOMAS April update.

gandul

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Re: The 2020 melting season
« Reply #1038 on: May 23, 2020, 12:08:50 PM »
Thanks Oren for posting this. We should review the state of Beaufort sea by the end of the month though. Lots of wind and ice more mobile right now.

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Re: The 2020 melting season
« Reply #1039 on: May 23, 2020, 12:23:09 PM »
Update on Hudson/Baffin to complement Aluminium's animations. uni-hamburg amsr2-uhh, may1-22
wipneus regional extent, may21 may22
« Last Edit: May 23, 2020, 08:39:02 PM by uniquorn »

Aluminium

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Re: The 2020 melting season
« Reply #1040 on: May 23, 2020, 12:27:43 PM »
200 000 m3/s of water with 10°C may melt 2.3 km3 of ice per day or 70 km3 per month. It may be significant with high efficiency. But it's not enough to determine strong melting season.

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Re: The 2020 melting season
« Reply #1041 on: May 23, 2020, 01:28:58 PM »
The albedo precondition in Siberian seas is much worse this year than 2012 (and very much worse than 2017-2019 years). Only hope the Beaufort and CAA will have more ice survived this year

Csnavywx

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Re: The 2020 melting season
« Reply #1042 on: May 23, 2020, 03:03:18 PM »

We don't know what is going to happen in June but so far we are likely going into June in best modern set up to ravage the inner Arctic basin.

I guess that's a matter of opinion. 2012 and 2016 had very weak freezing seasons which preceded them and set the stage with thinner ice. By comparison, 2020 was a much better freezing season. Hoping for a mid-May PIOMAS volume update which gives us a better idea of thickness.

That isn't what we use to define a melting season.

Everyone agrees that 2007 was the melt season on record.

Because the conditions for melt June-Aug were amazing.

If we had an exact repeat of 2007 weather wise we would crush 2012 lows.

The preconditioning that has taken place and is still to come taking place is putting 2020 in one of the best spots  going into June in modern times.

2020 having slightly more ice thickness means nothing if we have melt weather going into June.

Yep, 2011-2012 had a strong winter +AO (Arctic Oscillation) and high area/extent with more volume coming into that spring, yet it was quickly destroyed by preconditioning and the early June dipole. Winter/spring thickness does have an impact, but it explains somewhere around 30-40% of final volume. The rest is up to progressively earlier melt and albedo destruction as the Arctic warms up progressively earlier in the spring. (One small caveat to comparing directly to that season is that the 2011 melt season was a sneaky CAB ice destroyer that didn't show up particularly well on area/extent metrics.)

Speaking of preconditioning, MODIS is indicating some sneaky patchy surface melt and diurnal wetting of the surface in the CAB as we speak. There's a good chance we start seeing more substantial melt by the 28th as that new ridge attempts to set up. Surface temps have been running a little higher than would be expected given the 850/925mb temps we're seeing, but that's probably down to the fact that the big ridge we saw last week has effectively destroyed the low-level cold pool that's typically still present at this time. Since it cannot be regenerated radiatively given the (now) late May sun angle, this might prove crucial. Generally, in the warm season, it takes diabatic processes (cooling through precip and lift), cloud cover, fresh snow and recirculation within a low or TPV to generate a new cold pool and protect the ice. That can still happen, but we're running short on time before the onset of more severe preconditioning. The EC and GFS are in agreement that we should start to see near basin-wide melt starting on the 28th or so.

A couple of important surface stations to watch over the next week (in addition to MODIS pictures) will be Eureka (CWEU) and Alert (CYLT). If those stations are near or above freezing by then and we're seeing significant reddening on the 3-6-7 bands on MODIS, the game is on.


With the Hudson Bay region staying below normal temperature wise, this year is potentially setting up for a big June cliff (Bay melt will probably be delayed to coincide with Basin melt).
« Last Edit: May 23, 2020, 03:11:16 PM by Csnavywx »

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Re: The 2020 melting season
« Reply #1043 on: May 23, 2020, 04:03:37 PM »
With the Hudson Bay region staying below normal temperature wise, this year is potentially setting up for a big June cliff (Bay melt will probably be delayed to coincide with Basin melt).
At maximum on the 7th March Hudson Bay sea ice area was 4th highest in the satellite record.
On 22nd May Hudson Bay sea ice area was 4th lowest in the satellite record, with most area loss between 60 & 65 North.

Looking at the University of Bremen sea ice concentration map + GFS average temperature it looks like South of 60 North gets clobbered next.

I don't think melt will wait for June, except for Foxe Basin?
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Csnavywx

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Re: The 2020 melting season
« Reply #1044 on: May 23, 2020, 04:40:47 PM »
Yes, there was a nice little WAA event over the Bay (and another coming in a couple of days). However, the upper level pattern turns notably colder after that in the ensembles, so we should see a dip then a flattening or rebound through the first of June before seasonal climatology forces it down later on.

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Re: The 2020 melting season
« Reply #1045 on: May 23, 2020, 04:47:33 PM »
Hudson Bay ice tends to get compacted during the winter and spring months so is more resilient to heat than perhaps other areas and the low concentration areas you pointed out in other posts are melt ponds and not weak ice. It will be a normal melt season there in other words.

The forecast dipole is getting closer now, models seem to of upped the strength of the dipole although interestingly because of southerly winds over Svalbard fram export looks quite low in the forecast.

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Re: The 2020 melting season
« Reply #1046 on: May 23, 2020, 08:56:47 PM »
La Nina is ongoing.

Technically, it is not a la nina by most measures. The ENSO 3-4 region is projected to turn to a la nina later in the year, but at the moment it is in more of a neutral phase. Granted, it certainly looks like a la nina (which is extra concerning given the global heat anomalies this year).

The strange this about this year is that for a while it was trending toward a weak el nino, then the heat in that region just fell off a cliff.
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Re: The 2020 melting season
« Reply #1047 on: May 23, 2020, 09:04:38 PM »
Kara Sea, Kamennyye Islands upper left.

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Re: The 2020 melting season
« Reply #1048 on: May 23, 2020, 10:12:33 PM »
925mb temp anomaly for the first 3 weeks of May.
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Re: The 2020 melting season
« Reply #1049 on: May 23, 2020, 10:13:12 PM »

We don't know what is going to happen in June but so far we are likely going into June in best modern set up to ravage the inner Arctic basin.
<snip>
<snip>
2020 having slightly more ice thickness means nothing if we have melt weather going into June.

IMO, thickness is an important reflection of a preconditioning process which begins long before the melt season begins.

The CAB is the reservoir of most of the season ending ice. At 4/30/2020, PIOMAS was indicating ~ 500 km3 more ice in the CAB vs. 2019 and ~1,300 km3 more vs. 2017.  The Beaufort also was running a few hundred km3 above those years. You might characterize these as "slight" differences. I don't.

When faced with the prospect of cutting down a tree and a limited time frame to do, the thickness of the tree and the amount of time remaining to cut it down matter.

7 years ago I might have agreed with you, but my read of the last 7 melt seasons suggests to me otherwise.

By your logic, 2013 should have been a blow-out, as thickness and over-all volume were massacred at the end of 2012.  However, they were not, and the reasons why are the flip-side of the points Friv is making.  Preconditioning and weather are more critical to the melt season's progress than the modest increase in volume which may have been gained.  The additional ice won't be enough to off-set the increase in heat budget we are seeing, presuming weather continues on in the dismal trend it is currently following.

Continental snow pack has been smashed, especially in Eurasia, and the Siberian Arctic coast increase in temperatures are astonishing.  While we typically have not considered air temperature that significant a factor in direct melt, quantity has it's own quality, and we're talking about coastal temperatures running as much as 10-20C above normal and higher.  With sunlight at those temperatures, the ice may not even have a chance to form deep melt ponds as significant fractions of it sublimate directly to the atmosphere.  Flow off the continent will work like Foehn winds in the Alps which can strip snow pack in hours.

Like Friv, I think we are seeing late June ice conditions moving up to late May.  I think it's hard to understate the importance of this as it pertains to the Arctic heat budget. 

Instead of setting up to  do it's most efficient heat capture in July, its looking like it will be set up in early June *before* the solstice, which will effectively double the amount of peak insolation (Solstice +/- 3 weeks instead of the 3 weeks or so after) the Arctic will capture.  That will also have the effect of amplifying the impact of insolation later in July and into August, as proportionately more heat will be able to get captured by increased melt ponding and plain open water.

That's an awful lot of Joules, which in previous years would be mostly tossed back out of the atmosphere by albedo - by both the ice and continental snow pack.  None of that this year, and the result may be disturbingly spectacular.
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