ENSO对辽宁夏季降水预测指示意义的研究

根据1961～2009年辽宁省内53个气象站的夏季降水资料和同一时期的哈德莱中心的海表面温度资料,研究了辽宁省夏季降水与相对应的前一年秋季Nino3区海表面温度关系的年代际变化。结果表明,近30年来两者之间的相关性已经显著减弱。在1961～1974年这个时段,根据前一年秋季Nino3区海表面温度距平预测夏季降水,符号准确率在66.7%以上的站数达到25站之多,但在1980～2009年这个时段,达到相同准确率的站数却只有5站。在前一个研究时段,25个站点呈现块状分布的特征,主要位于辽宁的中部和东北部地区,但后一个研究时段内的5站分布呈现点状特征。在20世纪70年代中后期之前,当前一年秋季赤道中东太平洋海温偏高时,辽宁省夏季降水容易偏多;反之,当前一年秋季赤道中东太平洋海温偏低时,辽宁省夏季降水容易偏少。但自从20世纪80年代至今,上面描述的指示关系难以稳定成立。

Relationship between Summer Precipitation and ENSO in Liaoning Province

Based on summer precipitation data collected by 53 stations in Liaoning Province and sea surface temperature(SST)data of Hadley Center between 1961 and 2009,the inter-decadal variation of the relationship between summer precipitation and SST of Nino3 in the preceding autumn was studied.The results showed that this relationship was weakened evidently in the past three decenniums.Between 1961 and 1974,summer rainfall departure of 25 stations could be forecasted according to the SST of Nino3 of the preceding autumn,and the accuracy grade of anomaly sign was higher than 66.7%.However,the same accuracy was achieved in only five stations between 1980 and 2009.Between 1961 and 1974,the 25 stations were mainly clumped spread in the center and northeast of Liaoning.However,only five stations were fairly scattered.Before the late 1970s,Liaoning had more(less)summer rainfall,when SST was above the normal(below normal)over the central and eastern Pacific in the preceding autumn,and vice versa.Nevertheless,these relationships have weakened evidently after 1980s.