近四十年江苏省降水的变化特征

THE CHANGE OF RAINFALL DURING THE LAST 40 YEARS IN JIANGSU PROVINCE

本文利用江苏省35个站1951～1990年逐月降水资料,采用EOF展开方法分析了全省年、季降水量的时空分布特征。发现我省降水的空间分布和时间变化有如下特点:①全省降水量的年际文化总趋势基本一致;②同一年内,全省各地降水量距平符号常有南北相反的分布特征;③在降水的时间变化上,全省年降水量在近四十年经历了多——少——多的准周期过程,在60年代中期有一次跃变,由50年代多雨期进入少雨期,80年代后期降水有增多的趋势;④各季降水量的变化在不同地区有差异,80年代夏秋季节的降水量在苏南明显增多,而淮北呈现出降水减少,尤以冬春季节为重。

In this paper, the author deals with the temporal change and spatial distribution of the annual and seasonal rainfall in Jiangsu pronivce, using the EOF method and the data of monthly precipitation of 35 stations troml95l-1990. The major characters of the spatial distribation and temporal variation is shown by the first two principal components: 1. It is the first important feature that the tendency of the annual rainfall changes is consistent in the whole province; 2. The South-North seasaw pattern of the spatial distribation within a year is the second important feature; 3. During the last 40 years, it reveals a quasi-periodical Variation of rain fall. An abrupt change occured in the middle 1960s, from wet period toward to dry period. Until the end of 1980, there was an increasing tendency of precipitation; 4 The changes of seasonal rainfall were different between different regions.