Polar Plunges and Displacements

[Lettucing Gutted]

Is it possible to get Northerly (Southerly) cold surges across the whole Northern (Southern) Hemisphere without any compensating Warm Air Advection elsewhere? If so has there been any examples of this?

[johnholmes]

the short answer is no and the comment by CmD about resultant is correct in very simple terms.

[Thundery wintry showers]

Yes, I agree, it's impossible to get a polar plunge across the whole Northern Hemisphere.

It is possible for synoptic patterns to contribute to net positive and negative anomalies across the Northern Hemisphere though, due to the fact that oceans moderate the climate. So in January 2006, when synoptics prevailed that brought warm anomalies to the oceans, and cold anomalies to most of Eurasia, the mean positive temp anomaly was only very small; by contrast in January 2007, when the reverse was true, the mean positive anomaly was much larger.

However, even then we're talking fractions of a degree Celsius, and it has nothing to do with polar plunges affecting the NH; CMD and John are quite right that surges of cold polar air are always offset by surges of 'southerly' air somewhere else in the NH.

For an illustration, see the chart for 1 March 2006:

http://www.wetterzentrale.de/archive/ra/20...00120060301.gif

The northerly plunge affecting north-west Europe is offset by warm southerlies up the west of Greenland, and in east Russia/Siberia/west Asia, all as part of the same weather systems.

[WhiteFox]

For an illustration, see the chart for 1 March 2006:

The northerly plunge affecting north-west Europe is offset by warm southerlies up the west of Greenland, and in east Russia/Siberia/west Asia, all as part of the same weather systems.

Nice chart. Yin and Yang perfectly illustrated as the Eastern US is also receiving a cold plunge from the same system which is driving the warm southerlies up the West coast of Greenland.

You also know that a bit further West a high pressure is drawing warmer air up the Western side and so repeat until you come the whole way round....

[Lettucing Gutted]

Nice chart. Yin and Yang perfectly illustrated as the Eastern US is also receiving a cold plunge from the same system which is driving the warm southerlies up the West coast of Greenland.

You also know that a bit further West a high pressure is drawing warmer air up the Western side and so repeat until you come the whole way round....

I suppose that in times of the rare Cold Surges (Northwesterlies) that sometimes affect Northern India in the winter the extremely long Northerlies transporting cold air from Russia to Northern India would be matched by extremely long Southerlies transporting warm air as far north as the Bering Sea (to the east of the long Northerly) and Scandinavia (to the west of the long Northerly).