中文摘要：

利用NCEP资料计算NAM指数和标准化温度距平,对17次平流层弱极涡事件时亚洲东部温度变化进行了研究。结果表明：平流层环流异常比对流层温度变化超前约15天,地面温度变化的最大距平出现在平流层弱极涡后期,大约以40°N为界,北部比正常年份偏冷而南部偏暖。文中通过位势涡度的分布和变化以及500hPa东亚大槽的变化讨论了其影响过程和机理,在弱极涡初期和中期,自平流层向下,高位涡冷空气主要局限于60°N以北。从弱极涡的后期开始,在45°N以北地区,高位涡冷空气向南扩张,在对流层中上层,极地附近的高位涡冷空气扩张到45°N附近。同时,500hPa东亚大槽虽有加强,但低压区向东延伸,而贝加尔湖附近的高压脊显著减弱,致使槽后的偏北气流减弱,槽后冷空气主要影响中国华北、东北及其以北地区,造成这些地区偏冷。而40°N以南地区,从弱极涡的后期开始有南方低位涡偏暖空气向北运动,同时冷空气活动减少,地面显著偏暖。

英文摘要：

The variations of temperature in winter in eastern Asia during 17 stratospheric weak polar vortex events were investigated based on the standardized temperature departure and the Northern Annular Mode （NAM） index calculated by using NCEP data set. Results show that the circulation anomalies in the stratosphere occurred about 15 days before the temperature variation in the troposphere. In the latter period of the weak stratospheric polar vortex, the surface temperature departure reached its peak. At that time, the regions south of latitude 40°N were warmer than the climatic average and the regions north of 40°N were colder. The variation of potential vorticity and the Asian trough at 500 hPa are also taken into account when discussing the physical process and mechanism of the anomalous surface temperature. In addition, cold air with high potential vorticity remains near 60°N in the early and middle period of the weak vortex and begins to extend southwards in the late period. In the middle and upper troposphere, cold air from the high latitudes canmigrate to 45°N. At the same time, the Asian trough at 500 hPa becomes stronger and the low pressure region moves eastward; the ridge near Lake Baikal becomes weaker, the activity of cold air behind the trough influences Northeast China, northern China and more northerly regions and causes the surface temperature to fall. Moreover, warmer air with low potential vorticity moves from the south into the regions south of 40°N causing the surface temperature there to rise.