黄淮海流域盛夏月降水异常的时空变化

SpatialTemporal Variability of MonthlyPrecipitation Anomaly in Huang Huai Hai RiverBasin in Midsummer

利用１９５１～１９９５年７～８月黄淮海流域４３个站的月降水量及５００ｈＰａ高度资料，采用功率谱以及主相关型与ＥＯＦ相结合的方法，分析黄淮海历年７～８月降水异常的时空变化及其环流特征。主要结果为：黄淮海历年７～８月降水异常的多雨带分布存在着偏南型与偏北型，但７月两类雨型的多雨中心位置与８月不同。这两类多雨型与同期东亚５００ｈＰａ高度距平中心分布存在着很好的对应关系。历年７月两类多雨型的交替变化，存在着２．６ａ和１８ａ左右周期，而８月则存在着６～９ａ的周期。其７月的跃变发生在１９８０年附近，８月则发生在１９６５年附近。黄河下游８０年代盛夏的少雨干旱与其跃变有密切联系。

Based on monthly precipitation data from 43 stations in the Huang Huai Hai River Basin and height data on 500 hPa from 1951 to 1995, power spectrum analysis and principal correlation analysis, which is combined with EOF analysis, are used to study the spatialtemporal variability rule of precipitation anomaly and its relationship with circulation for July and August. The results show that during the past half century, there are two types of distribution of obvious pluvial belt in July and August, which are inclined to the south and north respectively. The locations of rainy center of these two types are different in July and August. There is evident correlation between the two rainy types and the distributions of height anomaly center on 500 hPa at the same time. In July, there is an alternation of the two rainy types, with periods of 2.6 years and 18 years, respectively, while in August, the period is 6~9 years. Climatic jumps of July and August happened near upon 1980 and 1965,respectively. The drought in the lower reaches of the Huanghe River in midsummer of the 1980s is closely related to the climatic jump.