西北地区夏季降水的气候特征分析

Analysis of Climate Character of Summer Precipitation in Northwest China

利用西北地区119站1961-2000年夏季(6-8月)降水资料,统计分析了各站历年夏季降水的平均场、方差场和各年代际平均值分布特征与整体总量逐年平均值的年际和周期变化特点,结果表明:西北地区夏季降水可划分为3个基本气候分区,即北疆区、中西部盆地沙漠区和东部季风影响区。中西部盆地沙漠区降水量和降水量方差均最小,处于稳定的干旱状态;东部季风影响区降水量的方差变化较大,降水的不稳定性增加,干旱频率增大;北疆区降水量较大,变差处于另外两区之间,表明旱涝影响微弱。各区的降水量在不同年代际间也具有不同的特点,降水量的变化会直接影响到当地主要旱地作物的产量。

Based on the summer precipitation （from June to August） data in the 119 meteorological stations from 1961 to 2000 in the Northwest China, the average precipitation and its variance, inter-annual and decades distribution characteristics average precipitation were calculated. The results showed that according to the summer rainfall the Northwestern China could be divided into three basic climatic zones, including North Xinjiang, Mid-west river basin dessert and East monsoon influenced region. Tne precipitation and its variance in the Mid-west river basin dessert region was lowest and in status stead drought. The precipitation and its variance in the East monsoon influenced region changed in a wide range with increased drought occurrence. The precipitation in the Noah Xinjiang region was high and changed not so big as in the East monsoon influenced region. Tne inter-decades distribution of precipitation in the three zones was different. Tne changes of precipitation could directly influence the yields of main local crops in drylands.