Cause of Extreme Heavy and Persistent Rainfall over Yangtze River in Summer 2020  

作　　者：Xiao PAN Tim LI Ying SUN Zhiwei ZHU 

机构地区：[1]Key Laboratory of Meteorological Disaster,Ministry of Education(KLME)/Joint International Research Laboratory of Climate and Environment Change(ILCEC)/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters(CIC-FEMD),Nanjing University of Information Science and Technology,Nanjing 210044,China [2]International Pacific Research Center and Department of Atmospheric Sciences,School of Ocean and Earth Science and Technology,University of Hawaii at Manoa,Honolulu,Hawaii 96822,USA [3]National Climate Center,Beijing 100081,China [4]State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics,Institute of Atmospheric Physics,Chinese Academy of Sciences,Beijing 100029,China

出　　处：《Advances in Atmospheric Sciences》2021年第12期1994-2009,共16页大气科学进展（英文版）

基　　金：This work was jointly supported by China National Key R&D Program 2018YFA0605604,NSFC Grant No.42088101,NOAA NA18OAR4310298,and NSF AGS-2006553;This is SOEST contribution number 11354,IPRC contribution number 1524,and ESMC number 350.

摘　　要：Record-breaking heavy and persistent precipitation occurred over the Yangtze River Valley(YRV)in June-July(JJ)2020.An observational data analysis has indicated that the strong and persistent rainfall arose from the confluence of southerly wind anomalies to the south associated with an extremely strong anomalous anticyclone over the western North Pacific(WNPAC)and northeasterly anomalies to the north associated with a high-pressure anomaly over Northeast Asia.A further observational and modeling study has shown that the extremely strong WNPAC was caused by both La Niña-like SST anomaly(SSTA)forcing in the equatorial Pacific and warm SSTA forcing in the tropical Indian Ocean(IO).Different from conventional central Pacific(CP)El Niños that decay slowly,a CP El Niño in early 2020 decayed quickly and became a La Niña by early summer.This quick transition had a critical impact on the WNPAC.Meanwhile,an unusually large area of SST warming occurred in the tropical IO because a moderate interannual SSTA over the IO associated with the CP El Niño was superposed by an interdecadal/long-term trend component.Numerical sensitivity experiments have demonstrated that both the heating anomaly in the IO and the heating anomaly in the tropical Pacific contributed to the formation and maintenance of the WNPAC.The persistent high-pressure anomaly in Northeast Asia was part of a stationary Rossby wave train in the midlatitudes,driven by combined heating anomalies over India,the tropical eastern Pacific,and the tropical Atlantic.

关 键 词：Yangtze River floods anomalous anticyclone over the western North Pacific CP and EP El Niño Indian Ocean warming La Niña Rossby wave train 

分 类 号：P426.62[天文地球—大气科学及气象学]