北京夏季旱涝的大气环流特征及其与前期北太平洋SST的关系

CHARACTERISTICS OF ATMOSPHERIC CIRCULATION DURING SUMMER DROUGHTS/FLOODS OVER BEIJING AREA AND THEIR RELATION WITH THE EARLIER STAGE SST OVER THE NORTH PACIFIC

利用 1 979～ 1 995年的NOAA/NCAR高空再分析格点资料 ,及同期北京夏季相当暴雨日数 ,冬季和春季太平洋海面温度资料、进行北京夏季旱涝对比和相关分析 ,结果表明 :北京夏季旱涝的平均大气环流形势有明显差异 ,且夏季涝年的平均大气环流距平场和夏季相当暴雨日数与大气环流的相关场都具有暴雨过程平均环流的主要特征 ;北京夏季相当暴雨日数和大气环流场都与赤道西太平洋 (暖池 )的春季SST存在显著的遥相关 。

Using the monthly re-analyzed NOAA/NCAR grid point data of 1979 to 1995, th e mon thly SST data over the Pacific and summer equivalent torrential rain day data of the Beijing area, a composite analysis of the mean atmospheric circulation duri ng droughts and floods and the correlation analysis between summer mean atmosphe ric circulation and earlier Pacific SST are carried out. There exist obvious dis crepancies in the mean atmospheric circulation during summer droughts and floods over the Beijing area. Both the departure field of the mean atmospheric circula tion in summer in flood years and the correlation field between the summer mean atmospheric circulation in East Asia and the number of summer equivalent torre ntial rain days in the Beijing area possess the main characteristics of the mean circulation pattern for the torrential rain process in North China. The correlation between SST of the Warm Pool and the number of summer equivalent to rrential rain days in the Beijing area passed the significance test. The earlier SSTA of the warm pool is a strong signal for the summer droughts/floods over th e Beijing area.