平流层爆发性增温的时空分布特征

利用1950～2003年逐日平均NCEP资料,对平流层爆发性增温（SSW）的特征进行了统计分析,得到如下结果：北半球SSW具有多发性,在这53年里共发现了69次增温事件,平均每年一次以上,有些年份甚至出现2～3次;SSW中心位置随高度变化,在较低层（16 km附近）中心位置大部分偏于西半球的北美北部到北极地区,高层（30 km附近）附近其中心多偏于东半球欧亚大陆的北边到北极地区;北半球SSW最先发生在30 km附近的欧亚大陆以北地区,然后由上向下延伸和传递,同时中心位置也逐渐转到西半球的北美大陆北端;在北半球发生SSW期间,平流层温度场和环流场的变化也会影响到对流层,引起对流层温度场和环流场的变化.对2002年9月发生在南半球平流层的一次强爆发性增温进行分析表明,南半球的这次SSW发生时表现出的特征与北半球稍有不同,在较低层（16 km附近）SSW中心出现在东半球的南端,在较高层（25～30 km）SSW中心位于西半球的南端.

The spatial and temporal distribution of the stratospheric sudden warming

The daily averaged NCEP data from 1950 to 2003 were used to analyze the characteristics of Stratospheric Sudden Warming(SSW).The results show that SSW in the Northern Hemisphere appeared so often that there were 69 SSW events during the 54 years and that they occurred more than once a year on the average,even twice or thrice in some years;the location of the warming center of SSW in the Northern Hemisphere changed with height at the lower level(near 16 km),mostly over the northern tip of North America to the Arctic in the western hemisphere;at the upper level(near 30km),it was mostly located over the north of Eurasia to the Arctic;SSW in the North Hemisphere usually occurred first near 30 km over the north of Eurasia,and then extended and transported from upper levels to lower levels with the warming center shifting gradually to the north of North America in the Western Hemisphere;during SSW,the change in temperature and circulation in the Stratosphere can affect the Troposphere,and lead to the change in temperature and circulation in the Troposphere.Besides the SSW in the Northern Hemisphere,the major warming that happened in the Stratosphere of the Southern Hemisphere in September 2002 was also analyzed.The characteristics of this SSW in the Southern Hemisphere differed somewhat from that of the North Hemisphere: at the lower levels(near 16 km),the warming center appeared over the southern tip of Eastern hemisphere,and at the upper levels,it was located over the southern tip of the western hemisphere.