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[各地气候]平流层突然变暖警告威胁欧洲大幅冻结

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更多 发布于:2018-02-11 18:48

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Weather models are suggesting a very high probability of a rare North Pole weather phenomenon called Sudden Stratospheric Warming (SSW) taking place later this month and bringing prolonged bitterly-cold temperatures to the United Kingdom and parts of Europe. Such weather event hasn't occurred since 2010 when it brought coldest March for 51 years to Scotland.
"There is a clear indication of an imminent split in the polar vortex, currently located over central-western Greenland. The main center will drift to the Canadian Plains, while a new area will form over northern Russia," TWC forecaster Dr. Dave Reynolds said. "This will drift towards the Caspian Sea, then westwards across the Mediterranean, Iberia and out to the near Atlantic during the next two weeks, weakening as it does so."
The polar vortex is expected to split during Thursday, February 8 and Friday, February 9, and become well developed by Sunday, February 11.






"The process of vortex splitting is accompanied by Sudden Stratospheric Warming, whereby temperatures in the stratosphere rise. This warming can then extend downwards through the depth of the atmosphere and result in an increased risk of blocking, which in winter-time raises the chance of widespread cold conditions developing," said Reynolds.


This process won't take place overnight as it usually takes 10 to 25 days to form and there is still uncertainty of how things will develop. However, computer models indicate a cold, blocked pattern over Scandinavia for the last week of February and first week of March, reinforced by a possible polar vortex split and accompanying stratospheric warming.


The warning is contained in the UK government official February to April forecast being briefed to the Cabinet Office, transport bosses, councils and emergency services.


The UK Met Office Meteorologist Aidan McGivern takes a look at the trend during the next 10 days and explains the phenomenon:A Sudden Stratospheric Warming is an event in which the polar vortex of westerly winds in the winter hemisphere slows down or even reverses direction over the course of a few days. The change is accompanied by a rise of stratospheric temperature by several tens of kelvins.
Although sudden stratospheric warmings are mainly forced by planetary-scale waves which propagate up from the lower atmosphere, there is also a subsequent return effect of sudden stratospheric warmings on the surface weather.
Following SSW, the high altitude winds reverse to flow eastward instead of their usual westward. The eastward winds progress down through the atmosphere and weaken the jet stream, often giving easterly winds near the surface and resulting in dramatic reductions in temperature in Europe.
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发布于:2018-02-17 21:45
极地漩涡刚刚分成两部分 - 准备迎接欧洲到美国的狂野天气

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The polar vortex just split in two… And this split will have far-reaching consequences for weather patterns from Canada to Eurasia. Since the polar vortex tends to be associated with some of the coldest air during the winter, the temporary separation means that ultra cold air is on the move. The latest split is likely to put Western Europe and much of Eurasia into the deep freeze for the rest of February, and will offer glimpses of hope for snow lovers along the U.S. East Coast.
[invensys于2018-02-17 21:51编辑了帖子]
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发布于:2018-02-17 21:47
看样子我国要大暖?
大冷岛五山站。
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发布于:2018-02-17 21:53

This split occurred in the stratosphere

The main polar vortex exists in the stratosphere, which is the layer of air above where most of our weather occurs. A sudden warming of the stratosphere over the Arctic, appropriately known as a “sudden stratospheric warming event,” took place in early-to-mid February, and this has caused the splitting of the stratospheric polar vortex.

Sudden stratospheric warming events occur when large atmospheric waves send energy upward, into the stratosphere, setting in motion a complex process that results in the temporary breakdown of the polar vortex. This February’s stratospheric warming event was particularly extreme, possibly setting records for how sharply temperatures spiked in the upper atmosphere.


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The polar vortex just split in two. Get ready for some wild weather from Europe to the U.S.

The polar vortex split isn’t the only factor favoring a cold snap in Europe, warmup in the Eastern U.S., and cool down in the West. There’s also a cycle of atmospheric pressure over the North Atlantic Ocean, known as the North Atlantic Oscillation (NAO), that can increase the odds of colder and snowier weather in some of these areas.

Computer models are projecting the NAO will become strongly negative during the next few weeks in response to the polar vortex split and stratospheric warming event, and this also favors cold and snow in Western Europe. (It also ups the odds of similar weather in the eastern U.S., but that may not happen right away.)
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