What I call the “Laptev Notch” is the area of open water which juts up nearest the Pole, from the Laptev Sea on the Siberian coast. The above Russian maps (lifted from the blogger “Brian D’s” comment over at an excellent post at Real Climate http://stevengoddard.wordpress.com/2014/10/21/spectacular-growth-of-arctic-sea-ice-during-nasanoaa-s-hottest-year-ever/#comments ) show how swiftly it is now freezing over. However the notch still remains.
The notch was created by a strong cross-polar-flow from Siberia to Canada last winter. The Laptev Sea always “exports” a lot of ice, as winds howl north from high pressure in Siberia. At times these winds push so much ice away from shore that open water called a “polynya” is created in the dead of winter close to the coast. As the wind coming off Siberia can be as cold as minus 70, this open water swiftly freezes over, only to again be pushed off shore. The amount this happens can vary, with four times as much ice “exported” north into the Arctic Basin during a productive year as during a less-productive year, though even during a less-productive year a lot of ice heads north. (We are talking about a quarter million km2 during a less productive year, a half million during an average year, and as much as a million during a hugely productive year.
It should be remembered that when you are talking about km2 of “exported” ice you are talking about area, and not thickness. As too often is the case with arctic ice, the actual volume of ice exported is hideously difficult to measure. It could be argued that a million km of six-inch-thick ice is less ice than a quarter million km2 of three-feet-thick ice. The counter-argument, which I think is valid, is that more water freezes when exposed to sub zero winds than is frozen when the water is sheltered by ice.
In any case, last winter a huge amount of ice was transported across the Pole to crush up against the north coast of Greenland and Canada, producing pressure ridges so impressive that one of the adventurers (who swarm out over the Pole in March and April, when the ice is safest,) described it as “crazy ice.” However this surplus on the Canadian side was paid for by a deficit on the Siberian side, where the ice was quite thin as the summer thaw began, resulting in swift melting and an area of open water extending towards the Pole I dubbed “The Laptev Notch.”
It should be noted that, while such open water does absorb more of sunshine’s heat than reflective ice during July and early August, it starts to lose more heat than ice loses from late August on. (When the sun gets down near the horizon open water can reflect more sunshine than ice, especially when the water is glassy.) Once the sun sinks below the horizon the open water loses a huge amount of heat to the atmosphere, which can then lose it to the darkness of space. Although the open water of the Laptev Notch likely has a lot to do with the air temperatures being warmer than normal this autumn up at the Pole, it is likely the temperature of the water itself is plunging, due to exposure to the air, even as the water is churned, due to exposure to the wind. Here is the DMI graph for polar temperatures:
It is interesting at this point to compare last year’s map (Oct 15; lower left) with this year’s map (Oct 22; lower right.) and see the differences. Despite the fact last year’s map is from a week earlier, The Laptev Sea is more frozen and the East Siberian Sea is entirely frozen.
This year the Laptev Notch remains open, though it is shrinking fast. It’s open water has (and is) likely losing a huge amount of heat from arctic waters. Meanwhile the Kara Sea is far more frozen than last year, and the Barent’s Sea, (which remained open deep into last winter), already is frozen to the north coasts of Svalbard and Franz Josef Land. Things are very different.
Last year the Siberian coast froze up in a nice, orderly progression, zipping-up from east to west, with the seas freezing starting with the East Siberian, then the Laptev, then the Kara, and lastly parts of the Barents. This year the large Laptev Notch has things out of kilter, and the Kara Sea seems likely to freeze first. What this may do to subsurface currents I can’t begin to imagine. I think it demonstrates how many variables are involved with sea-ice, and how people who pretend to understand it are basically talking through their hats.
In a most general sense, the shift in the location of sea-ice once again demonstrates how responsive the ice is to every twitch of the PDO and AMO. The PDO has spiked “warm” and less ice is on the coast of the East Siberian Sea. The AMO spiked “cold” last summer, and this is remembered by the ice against the north coast of Svalbard and Franz Josef Land.
The Laptev Sea is far from both the Atlantic and Pacific. There is debate about how much water from either sea reaches its coasts, and how regular the flow is, and also about the effects the regular and amazing summer flood of the Lena River has. Just to make things even more complex, I’ll throw in the idea that the Laptev Notch likely effects storm tracks, and perhaps even the upper air circulation, and has a part to play in whether the flow at the Pole is zonal or meridianal.
Currently the flow is more zonal than it has been in a while, as high pressure parks over the Beaufort Gyre. Earlier this autumn storms went wandering up to and across the Pole, and the flow was more meridianal, however the high pressure and its ridge across Scandinavia has made things zonal for over a week now.
Models suggest that high pressure and its ridge will slide south to Siberia, as the Icelandic low attempts to bulge north to the Pole, but then a new area of high pressure slide north from Canada, keeping the zonal flow alive. (As the Icelandic low bulges north Scandinavia could get into a southwest flow of mild, Atlantic air which might even briefly reach the Pole.)
I myself wonder if that high pressure could return, and the zonal flow could persist, without the Laptev Notch’s open water supplying spin to one side. Models tend to do a bad job when it comes to handling the changes caused by open water turning to ice-covered water.
If that cold air slides south towards Siberia as forecast it will likely swiftly freeze up the remaining open water in the Laptev Notch. This will result in a amazing increase in the extent of sea-ice. There will be all sorts of talk about the rate-of-increase. For a week or so the rate-if-increase may even approach record levels. However a better measure is to compare the current levels of ice with prior years. Using this measure it can be seen levels are becoming greater than we’ve seen in recent years.
Though this new ice will quiet the waters and allow stratification to begin in the waters beneath, the sea continues to loose a lot of heat through the thin in, until it thickens.
I’ll be watching to see if the flow remains zonal, which will keep the cold locked up at the Pole, or whether it becomes meridianal as soon as the Laptev Notch is gone, which will allow cold air to charge south and annoy the heck out of us.