关键词: 干旱, 气候背景, 海温, 季风, 大气环流

Abstract:

The characteristics of atmospheric circulation, climatic background, monsoon, SST and rainfall process of severe drought event occurred in the flood season of 2009 in Inner Mongolia were mainly analyzed in this paper. The results indicated that the less rainfall in flood seasons since 1999 in Inner Mongolia, the SST of the equatorial central and eastern Pacific entering into El Nino state in June of 2009 were the causes of the drought event in summer of this year. Moreover, the late onset and short lasting time over North China of South China Sea summer monsoon, and weak India summer monsoon were the main circulation background. In monthly mean height field at 500 hPa, a high pressure ridge at middle and high latitude of Eurasian continent had controlled Inner Mongolia region for a long time and a distribution of “west high east low” was shown in anomaly field, which were the main circulation patterns resulting in  severe drought in Inner Mongolia this year. And there was no effective precipitation in arid area. With the control of the high pressure ridge, the intensity of Northwest Pacific subtropical high had not changed the drought situation in Inner Mongolia.