Tuesday, 27 February 2018

Neven of Arctic Sea Ice Blog on Arctic winter melt

Talk about unprecedented



26 February, 2018


In the preceding post on Global sea ice minimum records getting broken for the third year in a row, I mentioned how the situation on the Pacific side of the Arctic was quite unprecedented, with the sea ice graph for the Bering Sea showing a sharp downturn (and even a small one for the Chukchi Sea). Well, there's an equally unprecedented event taking place on the Atlantic side of the Arctic as well. Yesterday, Prof. Dr. Lars Kaleschke from the University Hamburg tweeted out the following:

This probably has a lot to do with the splitting of the Polar Vortex due to a sudden stratospheric warming event a while back. I'm grateful for a bit of winter, finally, in my neck of the European woods, but not too happy about the consequences for the Arctic. The cause of all this heat and ice being pushed away from the northern coast of Greenland is an atmospheric set-up that during summer we'd be referring to as a Reverse Dipole (low pressure over the Canadian side of the Arctic, high pressure over the Siberian side). This animation of DMI SLP maps shows how the set-up got set up in the past 10 days, resulting in a pressure gradient as high as 75 hPa:
DMI SLP 20180216-25
Such a pressure gradient means lots of winds. The animation in Kaleschke's tweet shows what happened to the ice between Fram Strait and the Lincoln Sea, but here are two images by ASIF commenters Uniquorn and A-Team showing the situation (from the 2017/2018 freezing season thread):

Amsr2-nth-of-greenland-feb25


26 Feb 18 Fram Kap MJ Nares
In the same thread bbr2314 comments:
I can't imagine reds, however faint, have ever appeared in Northern Greenland in February before.
He's referring to these DMI maps for the 24th and 25th, showing the day 's surface mass balance compared to the day before (in mm water equivalent per day):
DMI SMB 20180224-25
It wasn't winds causing the surface in Northern Greenland to melt, it was heat. Robert Fanney posted a fantastic article on his Robertscribbler blog yesterday, describing the heat entering the Arctic during the past week: A Hole in Winter’s Heart: Temperatures Rise to Above Freezing at the North Pole in February.
An excerpt:
An extreme wave in the Jet Stream was developing and elongating over the North Atlantic, delivering more and more warm air northward.
By February 21st, the wave had extended into a knife-like extension east of Greenland and through the Barents Sea. Beneath this abnormal Jet Stream wave, which was starting to look more and more like a trans-polar river (of a kind predicted by Dr. Jennifer Francis as a result of human-caused Polar Amplification), was an intensifying thrust of outlandishly warm surface air.
Over the past 72 hours, gale force warm, southerly winds gathered in the Atlantic, then blasted north.
At this point, we were starting to see some seriously outlandish temperatures in the higher latitude regions. Cape Morris Jesup, which is the furthest north location on Greenland, by Friday the 23rd experienced a 6 C or 43 F temperatures on the shores of what should be a frozen solid Arctic Ocean just 400 miles from the North Pole.
The average high temperature in Cape Morris Jesup is -20 degrees Fahrenheit during February — making Friday’s reading a whopping 63 degrees F warmer than average. For reference, a similar departure for Washington, DC would produce a 105 degree day in February.
But it wasn’t just Cape Morris Jesup that was experiencing July-like conditions for the Arctic during February. For the expanding front of that ridiculously warm winter air by Sunday had expanded into a plume stretching tens of thousands of square miles and including a vast zone of temperatures spiking from 45 to 54+ degrees F above normal.
And at the center of the warm air pulse was today’s earlier reading of 1.1 C or or 34 F at the North Pole (see image at top of post). What would typically be a summer-time temperature for this furthest north location of our world happening during February. A highlight warm point in the midst of a vast plug of far warmer than normal air. A hole in the heart of winter.

Here's an animation of DMI temperature maps showing how these changes came about during the last 17 days:
DMI SAT 20180209-25
See how the blue gets replaced with green? Here's how this year stacks up, compared to 2013, 2014, 2015 and 2017 (2016 is missing from my archive):
2018 vs 2013-14-15-17

As I wrote in the preceding post:
There's so much heat coming into the Arctic from both sides that the temperature north of 80° is spiking to new record heights, as shown on Zack Labe's rendition of the DMI 80N temperature graph, and it will most probably climb some more.
And climb it did. I wonder if it will climb much more, as the current temperature is almost as high as the peaks for April:

DMI Zlabe
To close off, all of this is now even having an effect on the Central Arctic Basin sea ice area graph (hat-tip to Wip):

Nsidc_arcticbasin_area_byyear
Of course, that trend line will go up again, the open water north of Greenland will refreeze as soon as the winds turn, the surface of Greenland will stop melting. But talk about unprecedented!


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