中国东北地区干旱趋势的年代际变化

Interdecadal Variations of Droughts in Northeastern China

选用东北地区 (包括内蒙东部 ) 2 6个气象站的温度和降水资料 ,分析了近 5 0a来的干旱发展趋势和年代际变化。认为 :在向干旱发展的总趋势下还有明显的干湿年代际变化 ,温度逐年升高在干旱发展的总趋势中起主要作用 ,而降水的年代际变化在干旱的年代际变化中起重要作用 ,两者在 1 2和 2 5a的低频振荡上有惊人的一致性。这种低频振荡与东亚中高纬度地区的区域西风环流指数的年代际变化相联系 ,它们之间呈很好的反位相关系 ;降水与区域经向环流指数则有很好的同位相关系。但在近 5 0a的时间范围内 ,上述各项变化特征在后半期不如前半期的关系好。

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 the main tendency is towards to more dry years. Annual increases in temperature play a major role in the tendency of drought development but the interdecadal variations of 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.