Subseasonal and Synoptic Variabilities of Precipitation over the Yangtze River Basin in the Summer of 2020  

作　　者：Liudan DING Tim LI Ying SUN 

机构地区：[1]Key Laboratory of Meteorological Disaster,Ministry of Education(KLME)/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

出　　处：《Advances in Atmospheric Sciences》2021年第12期2108-2124,共17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 grants(Grant No.42088101,41875069),NSF AGS-2006553;NOAA NA18OAR4310298.This is SOEST contribution number 11413,IPRC contribution number 1541,and ESMC number 357.

摘　　要：Summer precipitation over the Yangtze River basin(YRB)in 2020 experienced a strong subseasonal and synoptic fluctuation in addition to contributing to an exceptionally large seasonal mean precipitation.The cause of this higher-frequency fluctuation is examined based on observational analyses.Apart from the continuous northward movement of the climatological mei-yu rainband,the mei-yu rainbelt in the summer of 2020 experienced multiple northward and southward swings.The cause of the swings was attributed to the subseasonal variability of southerly winds to the south and northeasterly winds to the north of the YRB.In addition,synoptic-scale variability,characterized by the eastward propagation of low-level cyclonic vorticity and precipitation anomalies,was also commonplace in the summer of 2020.While the strengthening of both the subseasonal and synoptic variabilities in the summer of 2020 was attributed to the increase of the background mean moisture,the synoptic variability was greatly affected by the subseasonal rainfall variability.As a result,both the synoptic-scale and subseasonal variabilities contributed to the north-south swings of the rainbelt.The large-scale modulations by both the seasonal mean and subseasonal anomalies provide insight regarding the optimization of issuing accurate,extended-range forecasts of extreme weather events.

关 键 词：Yangtze River precipitation synoptic and subseasonal variabilities meridional swings of a rainbelt large-scale modulation of high-frequency variability 

分 类 号：P426.6[天文地球—大气科学及气象学]