西北干旱区地气温差变化与黄河流域夏季降水的关系

Relationship of Differences between Ground and Air Temperature in the Arid Region of Northwest China to Summer Precipitation in the Yellow River Basin

本文利用西北干旱区92站1961～2008年逐月0cm地温和1．5m气温资料．黄河流域40站1961-2008年逐月降水资料，研究了我国西北干旱区春夏季地气温差与黄河流域夏季降水各自的变化特征．和二者之间的相关关系及其成因。结果表明：①黄河上游流域和河套地区平均降水量比下游流域少，且整体随时间有减少趋势，1985年之前降水量偏多，之后偏少。②西北干旱区地气温差全年6月最大，12月最小。春夏季地气温差空间分布为全区正值．年际变化存在整体增加趋势，1981年之前偏弱，之后偏强。③西北干旱区春夏季地气温差与黄河流域夏季降水存在反相关关系，地气温差偏强（弱）年，黄河流域夏季降水异常偏少（多）。

Based on the data of ground temperature, air temperature of 92 stations in the arid region of Northwest China, summer precipitation of 40 stations in the Yellow River Basin from 1961 to 2008 and NCEP reanalysis, the characteristics of differences between ground and air temperature in spring and summer in the Arid Region of Northwest China and summer precipitation in the Yellow River Basin are analyzed. The relationship and reasons of them are studied. The main conclusions are as follows： （1） The summer precipitation mean values of Yellow River upstream and Hetao area are higher than the downstream. And overall over time is to reduce trend, It＇ s above normal rainfall before 1985 and below normal after 1985. （2） The differences between ground and air temperature in the Arid Region of Northwest China have the biggest values in June and the smallest values in December. the values of is positive in spring and summer and overall over time is to reduce trend, It＇ s below normal rainfall before 1981 and above normal after 1981. （3）The differences between ground and air temperature in the arid region of Northwest China have great inverse correlation in the summer precipitation of the Yellow River Basin; That is to say, in the year of the differences between ground and air temperature is abnormal weaker （ stronger）, summer precipitation in the Yellow River Basin is more （ less ）. （4） The year of the differences between ground and air temperature is abnormal weaker compared to the year stronger in summer, at the 500hPa height field appears an opposite teleconncetion wave-train and from the height positive anomalies jumps to negative anomalies over China's Mainland. It＇ s unhelpful to summer monsoon rainfall in the Yellow River Basin.