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Wednesday, February 11, 2009

The Great Frost of 1709, the Winter of 2009, and the Polar Vortex

The Great Frost of 1709, the Winter of 2009, and the Polar Vortex

February 11, 2009

Dear Readers,

Some of the most popular articles posted recently on this blog have been about the 1709 Great Frost in Europe. That article came from New Scientist (click here and hit the page-down key twice). If you read it closely, you will notice that it mentions that the normal cause of cold weather in western European winters are the winds coming from Siberia and blowing toward the west, but in the winter of 1709, the winds were coming from the west and the south.

"The most immediate cause of cold winters in Europe is usually an icy wind from Siberia. 'What you would expect would be long runs of easterly winds with a well-developed anticyclone over Scandinavia sucking in cold air from Siberia,' says Wheeler. Instead, his data show a predominance of southerly and westerly winds -- which would normally bring warm air to Europe. 'There were only occasional and easterlies and those were never for more than a few days,' says Wheeler. Another odd finding was that January was unusually stormy. Winter storms tend to bring milder, if wilder, weather to Europe. 'This combination of cold, storms and westerlies suggests some other mechanism was responsible for that winter.' "

Right now, western Europe is again experiencing very cold and stormy weather (although, I dare say that once in a while this is to be expected in the winter, is it not?). Are there any similarities between now and 300 years ago?

Well, maybe.

NASA's Earth Observatory has posted an interesting report (click here and hit the page-down key twice) on the stratospheric conditions over the Arctic from January 10 through February 4. During that time, the polar vortex split into two vortices (click here to see the still graphic representations), and these vortices were consequently at slightly lower latitudes, spinning in counter-clockwise directions, thus pulling winds across northern Europe from the west.

[The animation of the splitting of the polar vortex is really fascinating. NASA's Earth Observatory has posted an animation that shows the changes in temperature in the stratosphere, going up to about 20 kilometers. What it shows is perhaps disturbing. But who really knows? The satellites have not been up there all that long observing. But to my simple eyes, it looks like our planet coughed out a bunch of really hot air straight up over the Arctic. Notice that temperatures start out in the -88 °C range, and by the time they finish, they have gone up to 12 °C -- and we are talking about the stratosphere here! not the surface. OK, so here is the link to the QuickTime animation -- it is well worth waiting for it to download. Note, also, that on occasion, the servers at NASA appear to be overloaded, so you may not always be able to get into the link, but keep trying.]

The New Scientist article points out that although there were three very large volcanic eruptions during the end of the Little Ice Age (a regional phenomenon, not a real ice age), the summer of 1707 was extremely hot, despite a solar minimum.

"...the 1690s saw a string of cold summers and failed harvests, while the summer of 1707 was so hot people died from heat exhaustion. Overall, the climate was colder, with the sun's output at its lowest for millennia. There were some spectacular volcanic eruptions in 1707 and 1708, including Mount Fuji in Japan and Santorini and Vesuvius in Europe. These would have sent dust high into the atmosphere, forming a veil over Europe. Such dust veils normally lead to cooler summers and sometimes warmer winters, but climatologists think that during this persistent cold phase, dust may have depressed both summer and winter temperatures."

I think we all remember that 2007 was an extremely hot year, and consequently the sea ice at the North Pole melted in a dramatic fashion.

But it would be a real stretch to try to say that that makes current conditions similar to those of 300 years ago.

And, these past few years, we have been having something of a solar minimum, too, but I doubt we can make any hay out of that, either.

No, the main thing to note, in my opinion, are not the similarities, but the fact that this year the planet appeared to belch out the excess heat that had accumulated at latitudes further south, when it moved north and appeared to blast through the vortex and split it.

OK, this is the first time that I have tried to embed a video, so let's see if this works: QuickTime video of stratospheric temperatures and the polar vortex splitting in two.

And, all I can say about that is that I hope that this manuever really got rid of some of the excess heat, thereby improving the Earth's energy imbalance. Does anyone have any thoughts on this? Would love to hear from you.

p.s. Oh, yeah, and before I forget, wasn't it in January that while temperatures in Europe and the U.S. were so low, the temperatures in the Arctic were so high that Arctic sea ice growth just about ground to a complete halt?

NSIDC (Click here and hit page-down key twice):

"...January 15 to 26, ice extent saw essentially no increase; an unusual wind pattern appears to have been the cause."

And, have a look at the truly sad state of the ice on January 23, 2009 (click here for the image). In fact, I just looked at today's Envisat image, and the sea ice to the north of Ellesmere Island and Greenland actually looks worse than it did on the 23rd.

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