江苏省夏季降水异常和成因分析

Summer Precipitation Anomaly and Its Causes in Jiangsu Province

利用1961～2006年江苏省59个台站的月降水量资料,将江苏省夏季降水进行EOF分析。通过研究降水异常的时空分布的演变特征,对江苏省夏季典型旱涝年进行分类,并初步探讨了夏季降水异常类型的成因。结果表明,46年来江苏地区夏季降水有比较明显的年代际变化,20世纪80年代开始发生局地旱涝的机率增加;该地区降水异常可以分为一致偏多型、一致偏少型、北多南少型和北少南多型4种类型,并且通过分析500和850 hPa环流形势、副热带高压和ENSO事件的特征,初步探讨了各类型发生的可能成因。

By using the monthly precipitation data in 1961-2006 at 59 stations in Jiangsu Province,the spatial and temporal characteristics of summer precipitation anomalies received by EOF are investigated.According to the evolution features of the spatial and temporal distribution of precipitation anomalies,the typical dry and wet years in summer are classified,and the causes of the summer precipitation anomalies are discussed.Results indicate that summer precipitation in Jiangsu Province has obvious decadal change in the recent 46 years,and the summer precipitation increases clearly from 1980s.The distribution of summer rainfall anomalies of Jiangsu Province can be divided into four categories,namely wet in whole province,dry in whole province,wet in North and dry in South,as well as dry in North and wet in South,and the possible causes of each category are explored through the analysis on the features of 500 and 850hPa circulation situation,the subtropical high and ENSO.