东亚经圈环流年代际变化及对海河降水影响  

Decadal Variation of East Asian Summer Meridional Circulation and Its Influence on Precipitation over Haihe River Basin

作　　者：李想[1] 高辉[1] 赵振国[1] 陈兴芳[1] 

机构地区：[1]国家气候中心,北京100081

出　　处：《气象》2013年第9期1119-1124,共6页Meteorological Monthly

基　　金：公益性行业(气象)科研专项(GYHY201306033);科技部国际合作项目(2009FDA23010);国家自然科学基金项目(41005037)共同资助

摘　　要：基于NCEP/NCAR和ERA-40两套再分析资料及中国160个站月降水资料,分析了海河流域夏季降水的变化特征及受东亚夏季风的影响,并定义了东亚夏季经圈环流指数,研究了东亚夏季风的年际和年代际气候变化特征及与海河流域夏季降水的关系。结果表明:近30年来,夏季东亚地区对流层低层和高层的西风均呈现反位相的变化特征,同时东亚地区对流层低层南风分量异常减弱,中低纬度的经圈环流也呈现减弱趋势,夏季风的强度随之减弱,不利于夏季雨带向北推进。文中定义的东亚夏季经圈环流指数与海河流域夏季降水存在显著的正相关关系,说明经圈环流指数值越大,东亚经圈环流强度越强,利于夏季东亚季风向北推进,从而使海河流域夏季降水偏多。反之,当东亚夏季风偏弱时,东亚经圈环流也偏弱,不利于海河流域降水偏多。本文结果表明,东亚经圈环流的年代际减弱是海河流域近30年处于少雨期的一个直接原因。Decadal variations of the East Asian summer monsoon and the summer precipitation are investi- gated by using the NCAR/NCEP and ERA-40 reanalysis dataset and the monthly rainfall data at 160 Chi- nese stations during 1951-2010. For better illustration, an East Asian summer meridional circulation in- dex （EASMCI） is defined in this paper and its relationship with the summer precipitation over the Haihe River Basin is analyzed as well. Results indicate that the westerly winds at both the lower and the higher troposphere in East Asia show anti-phase variations since the 1980s. Results also indicate the meridional wind speed at lower troposphere and the EASMCI have decreased in recent 30 years, weakening the sum- mer monsoon and blocking the northward movement of the summer rain belt. Statistical analysis shows a significant positive correlation between the summer precipitation over the Haihe River Basin and the EASMCI. Under the positive phase of the index, the East Asian summer meridional circulation is strengthened and accelerates the south wind to blow more northward, favoring the summer precipitation over the basin. However, under the negative phase of the index, the precipitation is less. In a word, the results in this paper demonstrate that the decadal weakening of the EASMCI is possibly a direct reason for the decrease of the precipitation over the Haihe River Basin in recent 30 years.

关 键 词：海河 夏季风 降水 东亚经圈环流 

分 类 号：P461[天文地球—大气科学及气象学]