A Review of Progress in Researchs of Stratospheric Sudden Warming

Abstract

After the discovery of the stratospheric sudden warming by SCHERHAG (1952) over Berlin much meteorological efforts have been directed to make clear the phenomenon in lower stratosphere of winter hemisphere.
There can be no doubt that the studies of the four major warmings in the Northern Hemisphere, occured during 1956/57-1967/68, play the important part in the advance in knowledge of the phenomena.
These studies are sorted in table 1 by period and approach which are classified (1) synoptic description, (1') analytical study, (2) energetics and (3) modeling. In the table winters are indicated in such manner as 1957/58.
Researches of energetics, in most of which calculations in the wave number domain are based on the SALTZMAN's method (1957), began to investgate the instability of polar vortex. They, however, revealed that the energy for polar vortex breakdown and for reversal of temperature field are transported from troposphere mainly as geopotential flux. But the physical mechnism of the breakdown and the reversal must be explained by model simulation.
MATSUNO's (1971) and NEWSON's (1974) model simulate successfully stratospheric sudden warmings in 1962/63 and 1972/73 respectively. That means that warming occures with upward propagation of planetaly waves (Charny and Drazin, 1961). Therefore it is possible that warmings happen every winter in the level higher than upper stratosphere. The reason why some of them leads to polar vortex decay in the lower stratosphere and others remain in upper layer is not yet clear.
Recent researches have owed its greater part to the developments in new observation techniques as rocket sonde and satellite. Papers based on the satellite data are summerized in table 2.
Warming phenomena in upper stratosphere and mesosphere without marked effects on the lower stratosphere are cited in table 3.
To answer the question whether in Southern Hemisphere major warming as in its counterpart occures or not, researches of Southern Hemispheric stratospheric warmings are listed in table 4 and examined. For the present we have negative answer.
Finally in table 5 studies in climatological spects as well as of phenomena after the period of table 1 are given as supplement.
Important problems remained today are :
1. to establish three-demensional structure of the stratospheric sudden warming extending to the upper mesosphere with data from new technique, and
2. researches on the relationship between stratospheric phenomena and troposphere are not yet sufficient, although its possibilities are expected through model experiments and discussed in many papers independently.