华北中部早涝成因的分析研究

ANALYTICAL STUDY OF FORMATIVE CAUSES OF DROUGHT AND FLOOD IN CENTRE OF NORTH CHINA

本文对北京等华北中部5站1956至1985年旱涝成因进行了分析讨论.结果表明,区域性旱涝主要是在海洋和局地土壤热状况异常作用下产生的.对华北中部而言,冬季黑潮海温与局地地温变化是引起汛期旱涝变异最重要的原因.前期下垫面热源异常对后期旱涝影响往往是通过累积的异常加热造成环流形势和系统的异常而实现的.海温与地温影响降水的机制不同,前者的影响是大尺度的,而后者的影响只是区域性的.当海温异常造成的大尺度环流变化与局地热状况都有利于降水时.洪涝更容易发生,反之易旱.

By using 30 years data of five stations in centre of North China including Beijing from1956 to 1985,we have analysed and discussed short-term climate variation,laying specialstress on interannual change of rainfall.The results show that regional drought and flood areformed under the action of abnormal heat condition of sea and/or land.As far as centralNorth China,anomalies of sea surface temperature in Kuroshio(SST)snd the local soil tem-perature(TG)are the most important contributing factors for drought and flood during floodperiods.Moreover,it also has been found out that it is through accumulative effect of abnor- mal diabetic heating which causes anomalies of general circulation and weather system thatvariations of heat source of underlying surface in earlier stage can influence drought and floodin later stage.The scale influenced by SST on rainfall differs from that by TG,the former islarge but the later is small.When both condition of large-scale circulation caused by SST andlocal heat condition are advantageous to rainfall,it is easier for flood to occur.On the con-trary,for drought.