大同市近50多年降水演变特征

Study on the Change of Precipitation in Datong City since Recent 50 Years

通过分析1955到2009年大同市各年代际的年平均降水量、各季降水、大降水(中量以上)日数、5—9月短时强降水、年最大日降水量的演变规律。结果发现:大同市年降水量趋于减少,年平均降水量20世纪50年代最多,从60年代开始减少,90年代略有增加但不明显。四季降水变化较大,其中夏季降水呈明显减少趋势,秋季降水增加,冬季降水增减幅度最大,80年代以后,平均降水量冬季增幅最大。近55年大雨(雪)、暴雨(雪)总日数呈减少趋势,其中大雨、暴雨日数明显减少,而大雪日数相对增加。短时强降水呈减弱趋势,年日最大降水量呈减小趋势。

In this paper,the change and trend of the decadal average annual precipitation, the seasonal precipitation, large precipitation （the amount above）,short of heavy precipitation during the period from May to September, maximum one day in Datong. The results showed that： annual precipitation undergoes a decreasing trend, the annual precipitation in Datong was the most in 1950s, it has reduced from 1960s, it has increased in 1990s but not significantly. It had larger change in seasonal precipitation, summer precipitation is decreasing, autumn precipitation was increased, and winter precipitation was the largest increase or decrease. The biggest increase in average precipitation in winter after 1980s. Nearly 55 years, heavy rain （snow）, rain （snow） tended to decrease the total number of days, including heavy rain, torrential rain days significantly reduced, while the relative increase in the number of snow days. Short-term decreasing trend of heavy precipitation, maximum precipitation in the 1st was a decline trend.