关键词: 干旱, 年代际变化, 子波分析, 区域纬向和经向环流指数

Abstract: Based on observed temperatures and precipitation from 26 surface stations in Northeastern China (including the east of Inner Mongolia), the tendency and interdecadal variations of droughts in the past fifty years were analyzed. The result showed that interdecadal variations of dry/wet years are clearly even though themain tendency is towards to more dry years. Annual increases in temperature play a major role in the tendency of drought development but the interdecadal variationsof precipitation are the main player in the interdecadal variations of droughts, especially in 12-year and 25-year periods of low-frequency oscillations. These low-frequency oscillations connected with the interdecadal variations of regional averaged westerly circulation indices in mid- and high latitudes of Eastern Asia with a good counter-phase relationship. The precipitation and regional averaged meridianal circulation indices, however, vary in the same phase. All these relations, however, are not as good in the second part of time as in the first part of time for the past fifty years. It may relate with the weak Eastern Asian monsoon due to the different degrees of global warming in higher and lower latitudes areas.

Key words: drought, interdecadal variations, wavelet analysis, regional averaged zonal and meridianal circulation indices