Study On The Dynamical Process Of Stratospheric Sudden Warming And Its Effects On The Distribution Of Trace Gases

Stratospheric Sudden Warming (SSW) is one of the most important characteristics in the stratosphere. A series of researches about the circulation variations of SSW and its relation with planetary wave have been done at home and abroad all the while and they gradually become a highlight and a frontier problem. In order to investigate the dynamical characteristics of SSW, the influence of SSW on the content and distribution of trace gases and the impact of SSW on the troposphere, on the basis of the data statistic analysis of the spatial and temporal distribution of SSW, E-P flux during SSW was calculated and planetary wave activity and variations during SSW was discussed; the residual meridional circulation was calculated and the transient characteristics of residual meridional circulation during SSW and the dynamical transport of ozone by the residual meridional circulation were studied, the variations of some other trace gases' distribution during SSW were analyzed by using HALOE; the possible influence of SSW on the climate especially over East Asia via NAM was investigated. The following results and new recognition were obtained.Firstly, by analyzing the NCEP data, statistic characteristics of SSW are obtained: the frequency of SSW showed mensal feature and it usually occurred in March; during the period of SSW, the location of the wanning center of SSW in the Northern Hemisphere changed with height and it has an obvious local property at each level, SSW often occurred foremost at upper level, and then extended and transported from upper levels to lower levels with the warming center also shifting, at upper level the warming center firstly occurred in the East Hemisphere, with SSW transporting toward lower levels, the warming center shifted gradually to the Western Hemisphere anticlockwise pass through the 180°meridian plane; When SSW took place, the temperature changed not only in the high latitude regions , but also in the middle-low latitude regions, i.e. when the temperature rises in the high latitude regions , it decreases in the low latitude regions; SSW's characteristics of the Southern Hemisphere in the September 2002 resembled that of the North Hemisphere.Secondly, the harmonics analysis of geopotential height fields was taken during SSW by using NCEP, the results showed that the planetary wave activity during SSW was not completely the same as Labitzke indicated, in spite of that the planetary wave of wave-number 1 unusually grows in the pre-SSW period and destroyed during SSW, the planetary wave of wave-number 2 has different feature in process of SSW. Corresponding with different planetary wave activity, breakdown of polar vortex was different. Planetary wave activity show in the following three types: (1), the planetary wave of wave-number 2 in the pre-SSW period is very weak, it unusually grows too stronger in the mid-SSW period. In this type the polar vortex breaks down and splits into two cyclonic centers; (2), the planetary wave of wave-number 2 in the pre-SSW period is correspondingly stronger, nevertheless, in the mid-SSW period, both planetary wave of wave-number 1 and wave-number 2 are distinctly weak, at the same time, the polar vortex moves outside of the polar region, but does not breakdown ; (3), planetary wave of wave-number 2 in the pre-SSW period is not very strong, while it develops slightly in the mid-SSW period, however, it can not surpass planetary wave of wave-number 1 in any case, simultaneously, the polar vortex firstly moves out from the polar region and then asymmetric distortion in form occurs. According to E-P flux, three types of planetary wave activity were discussed and the results showed that no matter what type of planetary wave of wave-number 2, it was in favor of the development of SSW.Thirdly, the transient residual meridional circulation was calculated during SSW via transformed Eulerian-mean thermodynamical equation and continuity equation by using ECMWF data for the composite analysis, and the general characteristics of residual meridional circulation during SSW was obtained, at the same time, the variation of the transient residual meridional circulation in the high latitude regions was analyzed during SSW. The results showed that the transient residual meridionalvelocity (?) at 10hPa～2hPa levels at the beginning of SSW changed gradually from southward to northward and northward wind turned stronger with SSW getting stronger , its intension increased with the increasing height, when SSW got weak, it slowly came back to southward wind with its intension stronger than that of pre-SSW period; the transient residual vertical velocity (?) at 10hPa～2hPa levels at the beginning of SSW changed gradually from weak ascending to sinking and its sinking became more stronger as SSW developing. When SSW became weak, it slowly came back to ascending with its intension stronger than that of pre-SSW period. The comparison between the transient residual meridional circulations which calculated with the term of wave heating or omitted wave heating, and the results showed that the term of wave heating in the upper stratosphere in the Polar Regions influenced transient residual meridional circulation and it was worth to be considered.Fourthly, the analysis of the distribution of ozone and other trace gases mixing ratio during SSW by using ECMWF data combining HALOE data showed that ozone mixing ratio in the high latitude increased during SSW with ozone mixing ratio decreasing in the middle latitude and this was validated by composite analysis; the net transportation of zone was calculated by using the calculated residual meridional circulation, the variation of ozone distribution was comprehensive analyzed according to the variation of planetary wave and dynamical transport of residual meridional circulation, therefore, mechanism of dynamical transportation about the increase of ozone was explained during SSW.Fifthly, by analyzing the relationship between Northern Annular Mode (NAM) and SSW and then discussing linkage between NAM and both East Asian jet and East Asian trough, the possible influence of SSW on East Asian jet and East Asian trough was investigated. The results showed that East Asian trough strengthened during SSW occurred, the influenced regions of East Asian trough shifted toward south with SSW transporting from upper to lower levels, thus, SSW has reference value for forecasting of East Asian climate.At last, we summed up the limitations of this paper and conceive the further work.