Possible impacts of ENSO on the intra-seasonal variability of precipitation over southern China
ZHANG Wenjun;LEI Xuben;GENG Xin;QI Li;Key Laboratory of Meteorological Disaster,Ministry of Education/Joint International Research Laboratory of Climate and Environment Change/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters,Nanjing University of Information Science & Technology;
In this study,the features of intra-seasonal(10—30 d)precipitation variability over southern China during the autumn,winter and following spring season of different types of ENSO events are analyzed based on the Hadley Centre sea surface temperature(SST),National Centers for Environmental Prediction(NCEP)and National Center for Atmospheric Research(NCAR)atmospheric circulation data,and China daily rainfall station data.The results showthat the impacts of different ENSO types on the intra-seasonal(10—30 d)precipitation variability over southern China vary with the different seasons.During the winter and following spring of EP El Nio events,the 10—30 d precipitation variability over southern China is significantly enhanced.Intra-seasonal precipitation variance is weakened during the CP El Nio autumn,yet strengthened during the CP El Nio winter,thus showing inverse features.The impacts of La Nia events on the 10—30 d precipitation variabilities are relatively minor and unstable.Further analyses showthat the impact on the 10—30 d precipitation variability is closely related to the responses of seasonal atmospheric circulation anomalies over the western North Pacific associated with ENSO events.Compared with normal years,a strong anticyclonic circulation anomaly occurs over the Philippines during the EP El Nio years.The anomalous southerly winds on the western side of the anticyclone transport much greater amounts of water vapor northward to southern China,which favors the strengthened 10—30 d rainfall variability.However,an anomalous cyclonic circulation occurs in the western North Pacific during the CP El Nio autumn,which suppresses the tropical water vapor transporting northward to the East Asian continent.During CP El Nio winters,an anomalous anticyclone appears over the western North Pacific,and though its intensity is weak,it accounts for the inverse lowfrequency rainfall responses in autumn and winter.When La Nia occurs,the anomalous cyclonic circulation over the Philippines is weak,which results in the relatively weaker responses of the 10—30 d precipitation variability over southern China.
【Fund】： 全球变化与海气相互作用专项(GASI-IPOVAI-03);; 国家自然科学基金资助项目(41675073);; 江苏省六大人才高峰和333高层次人才培养工程
【CateGory Index】： P426.6
【CateGory Index】： P426.6