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Author Topic: 2020/21 Freezing Season Predictions  (Read 603 times)

PragmaticAntithesis

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2020/21 Freezing Season Predictions
« on: September 10, 2020, 04:58:56 PM »
It's that time of year again, almost time for the least exciting but most important part of the ice cycle: freezing season!

I think this year's freezing season is going to be interesting, as the Great Arctic Anti-Cyclone has put a lot of heat in the peripheral waters, particularly on the Siberian side. Might we see a particularly low maximum next year as warm water fails to re-freeze?

Starting this thread before freezing season actually starts, as some people may want to predict things in advance.
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Phil42

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Re: 2020/21 Freezing Season Predictions
« Reply #1 on: September 10, 2020, 07:28:08 PM »
Not a very bold prediction given the state of the ice, but I predict a record or near-record late refreeze of the Kara and Laptev Sea. My reasoning behind this is because those two seas...:

a) had a very early complete melt-out this year. The Laptev Sea broke the record by about 2 weeks, the Kara had (eyeballing) a tied record-early melt-out with some other years. This can be seen in Attachment 1 (graph from here).

b) were exposed to very high temperatures compared to normal. Throughout the whole summer (and also a long time in spring) these areas recorded very high temperature anomalies. Because of the early melt-out, this additionaly means that during a long time period it was open water exposed to those temperatures. Here are the temperature anomalies for May, June, July and August.

c) are expected to keep being exposed to really high temperatures in the coming days, as can be seen in the 7-day forecast.

I think all these factors put together make a record-late refreeze possible or even likely. Of course cold, clear weather with little wind in October could change this outlook.

Paddy

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Re: 2020/21 Freezing Season Predictions
« Reply #2 on: September 10, 2020, 10:22:27 PM »
The linear trend would suggest an NSIDC March monthly average of about 14.4 m square km, based on eyeballing the graph here :http://nsidc.org/arcticseaicenews/2020/04/

The only firm prediction I'd make is that it'll be somewhere between 14 and 15 million square km, but if I had to go for one of our standard polling bins I'd say 14.25 to 14.75 square km. Which covers a range of outcomes from lowest ever to 7th lowest, so it seems fairly safe.

Niall Dollard

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Re: 2020/21 Freezing Season Predictions
« Reply #3 on: September 11, 2020, 12:15:20 AM »
Not a very bold prediction given the state of the ice, but I predict a record or near-record late refreeze of the Kara and Laptev Sea. ...
 Of course cold, clear weather with little wind in October could change this outlook.

I agree advancement of the pack towards the Russian side will be very slow.

On the other hand not too sure about advancement from the Russian coast. We have seen some wild temperature swings in Siberia of late and you could not rule out a cold October. The shallow coastal edge of the Laptev and ESS could see a rapid temperature drop. But there is a limit to how far this will extend and it is likely it still will be a long time before the pack joins up with ice coming out from the land.   

The remnant Beaufort ice will assist advancement here and subsequently north of Alaska. But Chukchi freeze up is bound to be slow and will be very dependent on synoptic situation in Nov/Dec.

Barents and much of Kara away from favoured coastal spots is bound to be very slow.

Another thing to wonder, is what will happen in the Nares Strait ? Last year I was surprised to see an early freeze up and back in 2012 after the record low extent, we did see an early November formation of the arch. North of Greenland much of the ice is thin - but there are some big blocks so who knows what could happen if a block arrives down at an opportune time (when combination of weather/wind/tides are favourable) ?

oren

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Re: 2020/21 Freezing Season Predictions
« Reply #4 on: September 12, 2020, 01:02:42 AM »
I think salinity can play a bigger role than water temperatures in determining difficulty of freeze-up. Seas that have been ice free for while, especially if they've been hit by repeated storms and wind events, will be well mixed and late to freeze. This would include all the Siberian seas as well as the Chukchi. OTOH the CAB, Beaufort and CAA should have an easier time.
As for the extent max, it is set in very peripheral seas, mainly the four Bs - Baffin, Barents, Bering and (B)Okhotsk, and isn't very interesting. However max volume in May 2021 could be relatively low if Arctic Basin refreeze is delayed. I think there is good potential for 2nd lowest max behind 2017.

Tor Bejnar

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Re: 2020/21 Freezing Season Predictions
« Reply #5 on: September 12, 2020, 02:50:49 AM »
A-Team just posted a photo in the MOSAiC thread showing some melt ponds frozen over and others not.  I bet salinity is the main difference.
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Comradez

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Re: 2020/21 Freezing Season Predictions
« Reply #6 on: September 15, 2020, 08:52:39 PM »
Will we see a full freeze-up of the Kara sea this winter?  I remember last year I was doubtful that we would see much of any freeze-up in the Bering Sea because 2019 saw an extremely early melt-out of the Bering and Chukchi...but then the Bering Sea froze right up and attained a fairly large extent in the spring of 2020.  So I guess the Kara will freeze-up like normal this year too, odds are.  But perhaps the "bight" of open water that usually reaches from the Barents Sea to the north of the Kara Sea will be especially pronounced next spring...and perhaps the Barents Sea will not witness much of an ice advance past Franz Josef Land and Spitsbergen this winter....

The Laptev Sea will freeze up for sure.  There's too much soon-to-be cold land surrounding it. 

If we ever get a real "Blue Ocean Event" one of these summers in the near future, we will probably see a "donut" of ice in the subsequent fall all around the landmasses ranging from north of Greenland, to north of the CAA, to the Beaufort, Chukchi, ESS, and Laptev, but with the CAB actually mostly open water or extremely slushy ice that never truly freezes into a solid pack that next winter, and probably the Kara too.