近50年长江中下游地区日照时数的时空特征及其影响因素

利用1961～2010年长江中下游地区93个站日照、降水、云量和风速资料，采用气候倾向率、突变检测和相关分析等方法，研究了长江中下游地区年、季、月日照时数的时空特征及其成因。结果表明，长江中下游地区年、季、月日照时数空间分布均呈东北多西南少的分布形式，夏季最多，其次为秋、春与冬季。近50 a长江中下游地区年日照时数普遍显著减少，区域平均减幅为682 h/10a，多于同期全国平均减幅,明显的年代际转折发生在20世纪80年代初期。年日照时数异常偏多出现在1963年和1971年，但未出现过异常偏少年。各季的日照时数也都是负趋势，夏、秋、冬3季减少显著，夏季减少最多也最明显，其次依次是冬季、秋季和春季。近30 a年及夏、秋、冬 3季日照时数减幅缩小，春季则转为以147 h/10a的速率在增加。除湖北中南部、湖南北部、江西北部、安徽北部和浙江东南部年日照时数在20世纪80年代有明显突变外，其他站点的年日照时数没有明显的突变。长江以北地区年日照时数减少与降水量增加和平均风速减少有密切关系，而在长江以南地区低云量的增加作用也非常重要

TEMPORAL AND SPATIAL VARIATIONS OF SUNSHINE DURATION AND ITS INFLUENCE FACTORS IN THE LOWER-MIDDLE REACHES OF THE CHANGJIANG RIVER IN RECENT 50 YEARS

Based on the sunshine duration,rainfall,cloudage,and mean wind speed data of 93 stations in the Lower middle Reaches of the Changjiang River during 1961-2010 with modern statistical diagnostic methods such as climatic trend rate,abrupt detection,and correlation analysis,the temporal/spatial characteristics and cause of yearly,seasonal,and monthly sunshine duration in the Lower middle Reaches of the Changjiang River were investigated in this paper.The results showed that the spatial distribution of yearly,seasonal,and monthly sunshine duration in the northeast of the Lower middle Reaches of the Changjiang River was more than that in the southwest of the reaches.The sunshine duration was most in summer,and next in autumn,spring,and winter.The yearly sunshine duration in the Lower middle Reaches of the Changjiang River in the recent 50 years was obviously widespread declined (682 h/10a),and the decline was more than that of the national average in the same period.The significant decadal change was in the early 1980s.The yearly sunshine duration was extremely excessive in 1963 and 1971,which caused by much summer sunshine duration,but no extremely deficient was observed in this period.The sunshine duration in spring,summer, autumn and winter also declined at the rate of 27 h/10a,375 h/10a,108 h/10a,165 h/10a respectively,especially in summer, autumn, and winter(p＜005).The most declination was in summer,and next in winter,autumn,and spring.The reduction rate of the sunshine duration in year,summer,autumn,and winter in recent 30 years reduced,but the sunshine duration in spring increased at the rate of 147 h/10a in the same time.The abrupt change of the yearly sunshine duration in the mid south of Hubei,north of Hunan,north of Jiangxi,north of Anhui,Southeast of Zhejiang appeared in the 1980s.Factors leading to the decreases in yearly sunshine duration varied greatly over different regions.The reduction of the yearly sunshine duration in the north of the Lower middle Reaches of the Changjiang River had close relationship with the increase of the rainfall and the reduction of the mean wind speed. Moreover the effect of the low level cloudage in the south of the Lower middle Reaches of the Changjiang River was also important