【摘要】 利用NCEP/NCAR月平均再分析资料,结合国家气象信息中心提供的1961-2007年4月中国596个测站月降水量资料,采用小波分析、相关分析和合成分析等方法,定义了春季南支槽强度指数和东、西位置指数,讨论了近60年两个指数的变化特征及其与中国同期降水和大气环流的关系。结果表明,春季南支槽总体呈强度减弱、位置逐渐西移的趋势。春季南支槽强度指数值越小(大),则南支槽越强(弱);春季南支槽位置指数值越大(小),则南支槽位置越偏东(西),出现长江中游及其以南部分地区降水越多(少),而西南的部分地区降水越少(多)的现象。另外,对两个指数与大气环流的关系分析表明,强度指数和位置指数与环流的关系比较显著,能够合理地给出中国降水差异的原因。更多还原

【Abstract】 The intensity index and east /west position index of Springtime Southern Branch Trough( SSBT) were defined and the pertinence betw een tw o indices w ere analyzed and the corresponding precipitation and atmospheric circulation in China,w hose variation features in last 60 years w ere discussed as w ell,using the monthly average of the reanalyzed data from NCEP / NCAR,combined w ith monthly precipitation data at 596 observation stations provided by NMIC,and employing the methods such as w avelet analysis,correlation analysis,etc. The results of the analysis indicate that the SSBT w eakens by intensity and moves w estw ard in general. And the smaller( bigger) the intensity index of SSBT is,the stronger( weaker) the SSBT is,while the bigger( smaller) the position index is,the easter( w ester) the SSBT leans,and the precipitation of the middle parts of the Yangtze River and its southern areas increases( decreases),w hile it apparently drops( rises) in southw estern parts of China. Besides,the relationship betw een intensity / position indices and circulation is also found to be very significant by analyzing their relevance,w hich explains the reason for the precipitation difference in China.更多还原