Revisiting the Second EOF Mode of Interannual Variation in Summer Rainfall over East China  

作　　者：Zhongda LIN Qin SU Riyu LU 

机构地区：[1]State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics,Institute of Atmospheric Physics,Chinese Academy of Sciences [2]Department of Atmospheric Sciences,Yunnan University

出　　处：《Advances in Atmospheric Sciences》2016年第1期121-134,共14页大气科学进展（英文版）

基　　金：supported by the National Natural Science Foundation of China (Grant Nos. 41375086 and 41320104007)

摘　　要：The second EOF（EOF2） mode of interannual variation in summer rainfall over East China is characterized by inverse rainfall changes between South China（SC） and the Yellow River-Huaihe River valleys（YH）.However,understanding of the EOF2 mode is still limited.In this study,the authors identify that the EOF2 mode physically depicts the latitudinal variation of the climatological summer-mean rainy belt along the Yangtze River valley（YRRB）,based on a 160-station rainfall dataset in China for the period 1951-2011.The latitudinal variation of the YRRB is mostly attributed to two different rainfall patterns：one reflects the seesaw（SS） rainfall changes between the YH and SC（SS pattern）,and the other features rainfall anomalies concentrated in SC only（SC pattern）.Corresponding to a southward shift of the YRRB,the SS pattern,with above-normal rainfall in SC and below-normal rainfall in the YH,is related to a cyclonic anomaly centered over the SC-East China Sea region,with a northerly anomaly blowing from the YH to SC;while the SC pattern,with above-normal rainfall in SC,is related to an anticyclonic anomaly over the western North Pacific（WNP）,corresponding to an enhanced southwest monsoon over SC.The cyclonic anomaly,related to the SS pattern,is induced by a near-barotropic eastward propagating wave train along the Asian upper-tropospheric westerly jet,originating from the mid-high latitudes of the North Atlantic.The anticyclonic anomaly,for the SC pattern,is related to suppressed rainfall in the WNP.The second EOF（EOF2） mode of interannual variation in summer rainfall over East China is characterized by inverse rainfall changes between South China（SC） and the Yellow River-Huaihe River valleys（YH）.However,understanding of the EOF2 mode is still limited.In this study,the authors identify that the EOF2 mode physically depicts the latitudinal variation of the climatological summer-mean rainy belt along the Yangtze River valley（YRRB）,based on a 160-station rainfall dataset in China for the period 1951-2011.The latitudinal variation of the YRRB is mostly attributed to two different rainfall patterns：one reflects the seesaw（SS） rainfall changes between the YH and SC（SS pattern）,and the other features rainfall anomalies concentrated in SC only（SC pattern）.Corresponding to a southward shift of the YRRB,the SS pattern,with above-normal rainfall in SC and below-normal rainfall in the YH,is related to a cyclonic anomaly centered over the SC-East China Sea region,with a northerly anomaly blowing from the YH to SC;while the SC pattern,with above-normal rainfall in SC,is related to an anticyclonic anomaly over the western North Pacific（WNP）,corresponding to an enhanced southwest monsoon over SC.The cyclonic anomaly,related to the SS pattern,is induced by a near-barotropic eastward propagating wave train along the Asian upper-tropospheric westerly jet,originating from the mid-high latitudes of the North Atlantic.The anticyclonic anomaly,for the SC pattern,is related to suppressed rainfall in the WNP.

关 键 词：Yangtze River rainy belt East China summer rainfall seesaw pattern South China pattern western North Pacific subtropical high extratropical wave train 

分 类 号：P426.6[天文地球—大气科学及气象学]