【摘要】 利用1951—2003年的Ni~no1+2,3,4和3.4区的海温异常指数,分析了各个海区3—8月海温异常随时间的变化与我国夏季降水的关系。研究发现4个海区海温异常变化与我国长江流域、江南地区、华北地区以及西北东部地区的夏季降水都有较高的相关性。合成分析表明:在海温异常随时间变化为正的年份,上述地区的夏季降水偏少;在海温异常随时间变化为负的年份,情况正好相反。在此基础上,分析了Ni~no3.4区的海温异常变化和高低空纬向风垂直切变之间的关系,发现海温异常变化与东亚夏季风的环流场之间也有很好的关系。由合成分析结果发现,在海温异常变化分别为正和负的年份,500 hPa高度距平场、850 hPa纬向风距平场、850 hPa流场距平场,200 hPa纬向风距平场及高低空纬向风距平切变均具有显著的差异,尤其是在长江流域以南、南海及我国的东北地区都呈相反的分布形势。因此,Ni~no3.4区的海温异常随时间的变化可以为东亚夏季风和我国夏季降水的预报提供一定的依据。更多还原

【Abstract】 East Asia summer monsoon has a distinct interannual variability,and the external forcing is one of main causes resulting in the interannual difference of East Asia summer monsoon,but the effect of the tropical sea surface temperature is the most prominent.Though SST is not the only factor that affects the weather and climate anomaly in China summer season,the tropical SSTA must be considered.Some previous researches only consider the influence of SSTA on East Asia summer monsoon in the different phases of warm and cold episodes.From the point of temporal variation,the study suggests a new point of view that the temporal variation of SSTA in the Middle and East Equatorial Pacific in spring-summer season has an effect on summer rainfall of China and East Asia summer monsoon.By using SSTA index of Nio1+2,3,4,3.4 from 1951 to 2003,the analysis on the relationship between each of four regions temporal variation of SSTA from March to August and China summer precipitation is carried out.In the years of positive temporal variation of SSTA,there is less summer precipitation to the south of the Yangtze,North China and east part of Northwest China.The opposite situation occurred in the years with the negative temporal variation.Particularly the correlation coefficient is the highest between the temporal variation of SSTA of Nio3.4 region and summer precipitation.Thus,some further researches have been conducted regarding the temporal variation of SSTA of Nio3.4 region as a prediction signal.By means of calculating the correlation between the temporal variation of SSTA in Nio3.4 region and the vertical shear of zonal wind in East Asia,it is found that there is a significant relationship between the temporal variation of SSTA of Nio3.4 region and circulation pattern of East Asia summer monsoon.Furthermore,the composite analysis is done for the years of positive and negative temporal variation of SSTA respectively.The result shows that there are obvious differences in the(500 hPa) height anomaly,850 hPa zonal wind anomaly,200 hPa zonal wind anomaly etc,especially to the south of the Yangtze River,South China Sea and Northeast China.The temporal variation of SSTA of Nio3.4 region in spring and summer can provide a prediction clue to the prediction of East Asia summer monsoon and the summer precipitation in China.更多还原