摘要
本文采用500hpa上的假相当位温θ_x和温度露点差(t—t_d)的候平均演变曲线,对比分析了长江上游旱年和涝年的夏季风活动规律,结果表明干旱年受夏季风影响时间短干洪涝年。通过500hpa上的候平均θ_x值,构造了一个表征当年夏季风特征的夏季风综合指数1_(csm),分析结果表明,该指数能反映出夏季风到达迟早、持续时间及强度等特征,为长江上游的旱涝预报提供了一个可靠依据。
In this paper, activities of the summer monsoon of the flood and drought years in the upper reaches of Yangtze River during floog season are discussed with curves of 5-day over-lapping mean ofθ_(?) and (t-t_d)at 500 hpa. The duration of the summer monsoon of the am-pleness of flood yesr is longer than the drought year. A new composite index of the summermonsoon (I_(csm)) with 5-day overlapping mean ofθ_s.at 500 hpa has been deeloped. Accordingto the results of analysis, this index can be used to describe the characteristics of the onset,duration and intensity of the summer monsoon. and provides a possible basis for flood anddrought forecast of the region.
关键词
长江上游
旱涝年
夏季风
the upper reaches of the Yangtze River
flood and drought years
summer monsoon
a composite index of summer monsoon
