2000年以来淮河流域夏季降水年代际特征及大气环流异常

Interdecadal Characteristics of Summer Precipitation over Huaihe River Basin and the Associated Atmospheric Circulation Anomalies Since 2000

利用1961—2016年中国642站降水资料和NCEP/NCAR再分析资料,分析了2000—2016年淮河流域夏季降水年代际变化特征及相应的大气环流异常,并探讨了2000年前后预测信号的转变。研究表明2000—2016年淮河流域夏季降水具有明显的年代际变化,2000—2008年为降水偏多期,2009—2016年为降水偏少期,且两个时期降水差异显著。降水偏多和偏少期对应的大气环流有明显差异,淮河流域多(少)雨期,贝加尔湖高压脊(低压槽)明显,乌拉尔山和鄂霍次克海为低压槽(高压脊),南亚高压偏弱(强)偏西(东),东亚副热带高空西风急流偏弱(偏强),热带东风急流偏强(减弱),同时与南半球的索马里越赤道急流、马斯克林高压和澳大利亚高压偏强(弱)有密切关系。前冬北太平洋涛动(NPO)可以作为淮河流域夏季降水的一个前兆信号,但2000年前后前冬NPO与淮河流域夏季降水的关系发生了年代际转折,2000年之前两者为明显的负相关,之后转为正相关。2000年之前冬季强(弱)NPO年与2000年之后冬季弱(强)NPO年对应夏季乌拉尔山和鄂霍次克海为明显的高压脊(低压槽),贝加尔湖为低压槽(高压脊),西太平洋副热带高压位于我国南海到菲律宾北部(台湾附近海域),有利于淮河流域夏季降水偏少(多)。

Based on precipitation data of 642 stations in China and NCEP/NCAR reanalysis data during 1961-2016,the interdecadal variation characteristics of summer precipitation over the Huaihe River Basin and corresponding atmospheric circulation anomalies since 2000 were analyzed,and the change of possible predictive signals around the year 2000 was discussed.The results show that summer precipitation over the Huaihe River Basin had obvious interdecadal change,which was from the period of more precipitation during 2000-2008 to the period of less precipitation during 2009-2016,and the precipitation differences were significant between two periods.The atmospheric circulations during the two different precipitation periods were obviously different.During the period of more(less)precipitation,the high ridge(low trough)over the Lake Baykal was obvious,the low trough(high ridge)over the Ural mountains and the Sea of Okhotsk was obvious.And the South Asia high became weaker(stronger)and shifted westward(eastward-shifted),the East Asian Subtropical Westerly Jet Stream was weaker(stronger),the tropical easterlies jet was stronger(weaker).Meanwhile,during the periods of more(less)precipitation,there was strong(weak)Somali cross-equatorial flow,Mascarene high and Australian high of southern hemisphere.The pre-winter North Pacific Oscillations(NPO)could still be a precursory signal of summer precipitation over the Huaihe River Basin.However,the interdecadal variation of relationship between the NPO and summer precipitation over the Huaihe River Basin had arisen around the year 2000.There was a significant negative correlation before 2000 and positive correlation after 2000.For both strong(weak)pre-winter NPO years before 2000 and weak(strong)pre-winter NPO years after 2000,the summer high ridge(low trough)over the Ural mountains and the Sea of Okhotsk was obvious,the summer low trough(high ridge)over the Lake Baykal was obvious and the summertime western Pacific Subtropical High was located from South China sea to north Philippine(sea area near Taiwan),which influenced summer precipitation less(more)over the Huaihe River Basin.