This is just a quick note to exclaim about how different the behavior of arctic systems are, compared to what traditional ideas expect. Traditionally we expect a boundary to exist between the the Polar Cell and the Ferrel Cell.
This boundary tends to have east winds north of it (Called “Northerlies”in the above illustration) and west winds south of it (called “Sou-westerlies” above). For the purposes of simplification, let me call them the “Polar Easterlies” and the “Sub-polar Westerlies.”
When these winds behave themselves, the only sign we have of the opposing winds is when a gale tracks northeast so far in the Sub-polar Westerlies that it leaves their jurisdiction, and enters the jurisdiction of the Polar Easterlies. That is when the gales slow, “stall”, and head east, with their track often describing what I call a “loop-de-loop”. This is commonplace.
It is more rare for the easterlies to come so far south that actual pockets of high pressure are carried east to west. In Eurasia such high pressure systems can be loaded with bitterly cold Siberian air, and be called names such as “The Beast from the East.”
Currently a second pocket of high pressure, “The Baby Beast”, is drooping the daffodils in England, but watch what happens to the high pressure as it is caught by the westerlies.
A.) It charges west over Britain.
B.) It runs out of steam between Britain and Iceland, and stalls.
C.) It is dragged back east, south of Britain towards Spain, by the westerlies, and has in fact become part of the westerlies.
If you go back to the first map, you will notice that when the Baby Beast plows into the westerlies the more traditional westerlies are suppressed south, as bigger than normal storms moving west-to-east through the Mediterranean. However the Baby Beast, like an oar moving through water, does not only make a whirlpool one side of its blade, but on both sides. Storms are also suppressed and squeezed north, up the east coast of Greenland. These northern whirls are in complete denial of traditional diagrams, for they are westerlies moving north of easterlies.
This situation is such a mutation of normalcy it cannot long survive. But for a moment in time one can see the sub-polar westerlies exist north of the polar easterlies, before the situation rectifies itself by dissolving into uncommitted confusion. (Called chaos.)
When one side of the Pole dissolves into such confusion, it ceases to have as much influence over the Pole itself. Its power is in a sense neutered. This gives the other side of the Pole relative strength. Even if it was weak, it gains relative power, compared to the neutrality of confusion.
Some computer models, trying to make heads of tails of this change, produce a remarkable solution. They replace the old polar easterlies with a new polar easterlies. Where the old were so far south they pushed the Baby Beast south over Britain, the new easterlies will be so far to the north a storm from the Pacific will be pulled north right over the Pole and down to the Atlantic.
We shall see about that. Models can be wrong. However what I wish to suggest is that the elegant idea of Polar Cell above a Ferral Cell is too simplistic to explain what we are witnessing.
Hopefully I’ll have time to add polar maps to this post, to show the view of what is occurring from above.
But, if I don’t have time, I should at least state that the newsworthy cold discharges may shift from the Eurasian side to the North American side, very soon.
When I last posted a weak “Ralpheena” situation was puncturing a zonal flow, with high pressure at the Pole attacked by both Atlantic and Pacific “feeder bands”. The Pacific milder air is seen in the isotherm map just north of the coast of Alaska, while the Atlantic milder air pokes up to the Pole west of Svalbard. A relatively mild current just west of Svalbard emphasizes the Atlantic mildness, and a slight polynya at the mouth of the Mackenzie River slightly emphasizes the Pacific mildness, but neither is even close to being as strong as the two flows that manifested in mid-February.
In February the Pacific band shifted towards Siberia as the Atlantic band won out, eventually making headlines by crossing the Pole, as the entire arctic high was shifted en mass, and described a slow arc, rotating west along the coast of Siberia, through Scandinavia, across the Atlantic to Greenland, and eventually through Canada to the Canadian Rockies. (The “Beast From the East”). The “Baby Beast” described above only represents a part of the arctic high pressure, a blob of it that breaks off and leaves the rest behind. In this sense the situation replicated itself in a minor way, but also was different because the high pressure held its ground, and no cross-polar-flows astounded anyone.
The first map shows one weak “Ralph” fading just under the Pole, and a second slightly stronger “Ralph” moving north in Fram Strait off the northeast coast of Greenland. This Atlantic inflow is nudging the high pressure towards Eurasia, and the “Baby Beast” extension is swinging around through Scandinavia, bringing an Atlantic gale to a halt southwest of Iceland.
By the 16th the Atlantic inflow is blocked. The “Ralph” in Fram Strait has weakened. On the Pacific side the “Hula Ralph” north of Alaska is being fed by continental air rather than maritime air, and is flattened.
The isotherm map shows two tiny pockets of the -40°C isotherm north of Greenland. This is somewhat rare over the Arctic Sea, because the water, though cold, is relatively warm compared to the air, and this heat radiates up through ice. Also the sea-ice is in constant motion, and full of cracks that open and then crunch together, and any time a lead opens water is in contact with the air and losing heat, even as it swiftly skims over with ice. The -40°C air shows the strength of the cold that has swiftly built over the Arctic Sea, (yet gets no headlines.)
By March 17th a secondary “Ralph” has developed from the weakening low in Fram Strait, and is southwest of Svalbard. The isotherm map shows a pretty example of the counterclockwise “hook” that characterized various incarnations of “Ralph” last year, but it is making little progress towards the Pole, as the high pressure seems to be fighting back.
Twelve hours later the secondary “Ralph” is being deflected east, with the isobars indicating strong winds north of Svalbard as the high pressure fights back. The small pocket of -40°C air north of the Canadian Archipelago reaches its largest extent. The Pacific “feeder band”, though an obvious stripe in the isotherm map, is completely cut off from the Pacific.
Twelve hours later the high pressure over the Pole is pumped up and has triumphed in the battle for domination of the Pole. The “Ralph” over Svalbard is being shunted towards Norway like a more normal North Atlantic gale in the westerlies. Perhaps it “pumped up the high pressure”, as all the air its clouds hoisted aloft had to descend somewhere.
One thing unseen in these top-down maps is a constant bleeding-off of the Pole’s frigid air down through Canada, via an extension of the high pressure in that direction. As that lobe pours cold south on its eastern side some mild air comes north on its western side, which partially explains the milder air north of Alaska. But the exchange is not as dramatic as earlier this winter, when the entire Arctic Sea was divided by milder air as the mass of cold moved south.
This morning the former “Ralph” has moved southeast to northern Scandinavia, and has become a part of a conglomeration of low pressures extending all the way to the western reaches of the Laptev Sea. This power is suppose to shove the high pressure off the Pole and down into Canada. As that high pressure departs there should be a Pacific to Atlantic cross-polar-flow develop behind it, in the clash between low pressure on the Eurasian side and high pressure on the Canadian side. A small low may zip along this flow from the Pacific to the Atlantic. Not that I will have time to watch it. If the high pressure over the Pole actually does descend into North America I could very well be shoveling snow in April.
It is ironic that the coldest temperatures we have seen all winter over the Pole waited until the time we expect to see them rise.
Until this cold is budged off the Pole I doubt we can officially claim the “yearly high” has been reached in terms of “sea-ice extent”. The peak has occurred later than usual in recent years. I’ll post on that next week. There is usually a lot of hoop-la about how low it is, though this year’s hoop-la might be a bit muted due to the fact the current “extent” has caught up to prior years and is no longer the “lowest evah!”