Even back when we had sea-ice cameras, they tended to go dark this time of year, as did the visual satellite, but even despite that darkness this was (and is) a fascinating time of year at the Pole. The darkness is at its most complete, and we enter sixty days when twilight recedes to the Arctic Circle.
The diurnal effect of temperature, rotating clockwise around our arctic maps, for a time all but vanishes. Even at the edges of the circular maps, where the sun does rise, the sun is so low and the days are so brief that the diurnal rise is slight. In fact Siberia and arctic Canada are better at losing heat than the Pole (because the heat of the ocean radiates up through the sea-ice) and are often colder. Even when a zonal flow keeps air “locked up” at the Pole, frigid air masses can be generated independently over Siberia and Canada, and sweep south to catch the unwary off guard.
Because we are free of diurnal temperature we can become fascinated by other diurnal effects, such as tidal or Barometric effects. (Or at least I can.) For example, what happens to the tidal effect of the sun when it is below the horizon? Does the sea-ice rock to the east and west with tides up at the top of Fram Strait as much in the winter as it does in the summer? If it rocks less does it freeze better?
Having the sun never rise makes it easier to see if warm air is invading from the south. You don’t get fooled by sunshine because there is none. (There are not many times in life it is so easy to subtract the influence of such a major effect.)
Last year I called these influxes “feeder bands” because they seemed to fuel the persistent area of low pressure I dubbed “Ralph”. This year is proving different. I find it somewhat annoying, because all the nice, neat ways I had of viewing things are made a shambles. But I’ll get over it, for change has a better side: It is fascinating.
We recently had a nice influx of milder air up into the areas above 80° north latitude. While it is nowhere near as impressive as last year’s record-setting plumes, it still shows up nicely on the DMI graph.
Therefore, though I am very busy in other areas of my life, I was of course curious to see if “Ralph” would reappear. In theory the mild air, rising, would create low pressure at the surface.
When I last had time to post on November 14 the “feeder band” extended up through Scandinavia and right across the Pole, curving towards Greenland (seen in the temperature map.) A “Ralph” was forming north of Greenland.
Last year (perhaps due to more potent, milder impulses as an after-effect of the 2015 super-El-Nino) Ralph would have bullied the high pressure off the Pole, but this year the high pressure pushed back. Ralph was squashed west across the Canadian Archipelago, as Atlantic Gales were repressed along their usual west-to-east route, and an Aleutian Low came further north than usual and crossed west-to-east from Siberia to Alaska north of Bering Strait (which seemed to be a pattern this autumn.)
By November 17 the feeder band has broken down, and though the milder air is over the Pole it is cooling quickly.
By November 18 Ralph is a pathetic blip on the Canadian side of the Pole, and the high pressure is expanding. The influx of milder air is still clear in the temperature maps, but cloud-cover maps showed fewer clouds than I’d expect, and very clear skies towards Greenland.
By November 19 the clear skies moved towards the Pole, and the high pressure was pumping up. Where last year the Pole likely lost much heat through uplift and latent heat being released as moisture precipitated out as snow, this year clear skies are allowing radiational cooling. The mildness of the “feeder band” is all but gone from the temperature map. The high pressure is so strong that the next west-to-east Pacific low is crossing Bering Strait further south. (Last years such lows sometimes came right north to the Pole, and I dubbed them Hula-Ralphs.)
By the 20th the high pressure at the Pole is one of the strongest I’ve seen. (Blue is above 1050 mb).
And this morning has me shaking my head. This is about as opposite a “Ralph” as you can get. The clockwise winds on the Atlantic side are effectively cutting off all Atlantic moisture from getting to the Pole, and though mild air is coming north through Being Strait, it is being swept east as an easterly flow that likely will cause the next Pacific storm to take a wrong-way route, along the Siberian coast east-to-west rather than west-to-east.
The current situation is fascinating for a number of reasons. Closest to home, when a high pressure like this has a lobe over Greenland it can breed storms on the east coast of the USA. (Those of you who insist upon using old-fashioned maps, that look at the earth sideways, know such high pressures as “blocking highs”.)
Another switch from earlier pattern is that sea-ice will be pushed down the east coast of Greenland, even as ice forms along the coast due to cold winds. Considering such sea-ice is basically leaving the Arctic to enter the Atlantic, any spike in sea-ice extent it causes is artificial, as the ice will melt by June. (However, if enough goes down the coast, it can cool the Atlantic, which I suppose influences sea-ice extent in some future time.) Ice extents remain well above last year’s.
It appears that while winds will push ice from around Svalbard and Barent’s Sea southwest into Fram Strait, winds north of the Strait will not be so helpful, and will keep ice from coming south.
A comparison of NRL maps shows much more sea-ice in the north of Barents Sea, and Kara Sea nearly full of sea-ice, which is indicative of the lack of southern surges that made last year so interesting (and pushed so much sea-ice north.) (2016 left; 2017 right)
There continues to be less ice on the Pacific side, but Hudson Bay has started its freeze earlier. It can freeze over with astonishing speed. Susan J. Crockford at Polarbearscience.com reported that the people of Churchill stated the coastal freeze-up was one of the earliest since 1979.
Lastly, the big high pressure at the Pole will offer me a chance to study the Polar Easterlies, which tend to be ephemeral and elusive, especially when Ralph is around.
Perhaps a good (although simplistic) way to think of the Polar Easterlies is to think of the track of a long lived hurricane. In the tropics it heads east-to-west, in the Trade Winds, but then curves and heads west-to-east in the Westerlies. Usually it transitions to a gale as it comes north, but if that gale gets far enough north it curves back to the west (often preforming a sort of loop-de-loop). That curve back to the west is the Polar Easterlies.
A lot of the time these east winds just seem to be the northern sides of Atlantic or Pacific storms in the Westerlies, but at other times they carry storms along with them (as seen in the case of the very weak version of “Ralph” in the above maps, and also in the Pacific storm which like will move east-to-west on the East Siberian coast this week.)
Also I keep thinking I glimpse some impulse or force moving against the Westerlies at high latitudes. I forget the name I gave it last winter, but I seemed to notice the “feeder bands” that fed Ralph rotated around the Pole in a clockwise manner.
I’m very unsure what I am seeing (or even if it is real) but I am going to keep myself entertained by continuing to scrutinize maps for it, (even if it is a mythical Bigfoot). I think it will be accented by the current Anti-Ralph at the Pole.
(In case you think it foolish to call a high pressure an “Anti-Ralph”, I must confess I have always though it was foolish to call a nice, sunny day an “anticyclone”. It always seemed sort of like calling sunshine “anti-rain”.)
Have a Happy Thanksgiving, and stay tuned!