Ffive

GEOS-5 Analyses and Forecasts of the Major Stratospheric Sudden Warming of January 2013 http://gmao.gsfc.nasa.gov/researchhighlights/SSW/

Its clear from what I read on here that there is a lot of knowledge and learning contained in these threads. I did mention briefly in my post of Nov 30th (page 29) that the Major SSW of 1962/63 is probably a bench-mark. The MAJOR STRATOPHERIC WARMING of (JANUARY)feb 1963 is worth studying in detail,as the Mid winter warmings of 1957 1958 were strikingly similar. The initial warming started at 10mb level in mid-January and turned out to be,almost, (THE PERFECT STORM).....TO COIN A PHRASE. for us in the UK. I,m sure your ALL familiar with the (dynamics)of planetary wave-zonal flow coupling, through eddy heat transport. The reason I think the UK in that winter, was perfectly placed to benefit from the MAJOR ssw was that at the time there was a large-scale (quasi-stationary wave set-up.....zonal harmonics....1 and 2.There was a rapidly building Atlantic Anticyclone,and a more diffuse Anticyclonic system stretching across Asia,from the western Pacific Ocean.Over simplifying things....as there were other factors as well,Oscilations in planetary waves and the mean (zonal wind) strength seem to correlate well.(strong planetary wave-zonal coupling). Seems to me that,free planetary wave (MJO) moving wesward(16 day period)PHASED WITH STATIONARY WAVE,greatly enhanced the wave amplitude,and northward transport of heat.This is one of the reasons for the "explosive warming"that took place in the mid-stratophere from mid-late Jauary. Iteresting to note some the parallels in the mid-winter warmings of both 1957 and 1963. (a) the large temperature rises initially appeared during the middle of January over southeastern Canada within the Southerly flow of a deep North American Polar Trough and intensifying Atlantic anticyclone. (b)The warm air thereafter spread generally Northwest in a direction nearly perpendicular to strong southwesterly jetstream. © At the peak of the warming phase,temperatures at the 10-mb level near the warm center reached maximum values of about 0C. (D) A MAJOR FEATURE.....of the circulation break-down,was the plunge of a cut-off low and cold center southward across North America at the same time warmer air overspread the polar region. f5

First post from me for a VERY long time. Been following this Strat-thread for a long time now,some very knowledgeable people on here. Fascinating subject and i,m pleased to see Stratospheric Dynamics being used as a forecasting tool. About 14 years ago on (Other)weather site......I was very keen to get across the importance of Strat-Dynamics in the overall pattern of Northern Hemisphere winters.Nobody at the time, gave it much credence(apart from Steve Murr).I think he realized, as I did,that really, the wintertime polar vortex is the governor.Liken it to a giant flywheel,it gains its energy from the thermal gradient in autumn/winter.Like a flywheel,if you knock it,it will loose energy and slow down,untill it gains MORE energy,and speeds up again. Keep on knocking it and you will eventually slow it right down......and stop it. I think the classic events that took place in the Stratophere in December 1962,and Jan/Feb 1963 can be used as a benchmark in Tropospheric/Stratospheric dynamics.In late December 62,and early Jan 63 the polar vortex was a very cold,almost circumpolar cyclone.(This ties in with what Chionomaniac was saying about the vortex strength)It seems to me, that the kinetic energy that the votex gains,ultimately, can sometimes lead to its own DISTUCTION.The central temperatures of the votex were near to -85C,with a band of westery winds at 10mb sometimes exceeding 200kt. The Major Stratopheric Warming then was quite astounding,and explosive.Around the middle of January,10mb temperatures above Edmonton,Alberta.began a rise.Over five days,the temperature rose 67C.The changes in circulation in Jaunuary and February 1963 extended from the Tropopause to at least 55km. F5