太湖无锡地区近40a来日照的变化特征分析

利用无锡站1961—2000年日照时数、日照百分率、总云量及低云量资料，对太湖无锡地区近40a来日照的变化特征进行分析，阐述了其年变化及多年变化特征，分析了日照时数与日照百分率、总云量、低云量之间的关系。结果表明：日照时数呈减少趋势，年日照时数的减少幅度为99．72h／10d，其中又以夏、秋季减少最快；日照时数年内变化为夏秋季大、冬春季小；日照时数与日照百分率变化趋势不完全相同；日照时数与总云量、低云量呈负相关；年日照时数存在突变现象。

THE ANALYSIS OF VARIATION CHARACTERISTICS OF SUNSHINE IN THE RECENT FORTY YEARS IN WUXI REGION

Based on the data of sunshine hours,relative sunshine,total cloudiness and lower cloudiness from 1961 to 2000 in Wuxi observation station,the variation characteristics of sunshine hours in recent years in Wuxi region are analyzed.The monthly and yearly variation of sunshine hours,the relation between sunshine hours and relative sunshine,total cloudiness,lower cloudiness are studied.The results show:sunshine hours has greatly decreased in the recent 40 years,with the breadth of 99.72 h/10 a and decreased fastest in summer and autumn;the monthly variation of sunshine hours is bigger in summer and autumn than that in winter and spring;the monthly variation tendency of sunshine hours and relative sunshine is different;there exits negative relevance relation between sunshine hours and total cloudiness and lower cloudiness;the sudden change of sunshine hours occurred in 1987,and then there is a relative less hours period.