湘潭市近30多年降水变化特征分析

利用湘潭市1971￣2004年逐月降水资料,分析了湘潭市近30多年降水变化特征。结果表明,湘潭地区年降水呈准20年周期变化,春季呈"多-少-持续偏多"的变化趋势;夏季呈"持续偏少-多-少"的变化趋势;秋季呈"少-多-正常-少"的变化趋势;冬季呈"少-多-正常-多"的变化趋势。从年内变化看,1971￣2004年30多年来平均降水量最大的是6月份,达到211.9mm,最少的是12月份,为40.8mm;大雨发生频次为9.3次/a,暴雨发生频次为3.8次/a。

Precipitation Character Analysis in the Latest 30 years in Xiangtan

Based on the precipitation materials of Xiangtan from 1971 to 2004, statistical analysis are carried out by year, season, month scale. The results show that the precipitation period is about 20 years. The precipitation change tendency of Spring is "much-few-continuous much", that of Summer is "continuous few-many-few", that of Autumn is "few-much-normal-few", and that of Winter is "few-much-normal-much". The biggest average precipitation by year is 211.9 mm in June, and the lowest average precipitation by year is 40.8 mm in December during the past 30 years. The heavy rain frequency is 9.3 time/a, and the rainstorm frequency is 3.8 time/a.