Impacts of Types and Intensities of El Ni?o Events on Precipitation in Autumn Flood Season of Hainan Island
By using the 1961-2018 monthly sea surface temperature(SST)index data in the Nino key area,NCEP/NCAR reanalysis data and precipitation data of National Meteorological Observatory as well as the correlation analysis and composite analysis methods,this article analyzes the impact of differ-ent types and intensities of El Niño events on precipitation in autumn flood season in recent 58 years of Hainan Island and the corresponding differences in atmospheric circulation and water vapor transport field on the basis of defining the types and intensities of El Niño events.The results demonstrate that El Niño events make for the decrease of the autumn precipitation generally,but they have differences in type and intensity.In the years with central Pacific El Niño events in light intensity,the probability of 32.5％less than average precipitation in the whole island of Hainan increases by 25％relative to the climatic proba-bility.Moreover,the spatial distribution of precipitation anomaly is more in some southwestern areas but less in other areas of Hainan Island.In addition,the probability of 21.7％less than average precipitation increases by 11.7％compared to the climatic probability in the years with eastern Pacific El Niño events in medium and higher intensities,while the probability of 15.8％less than average precipitation increases by 7.5％relative to the climatic probability in the years with eastern Pacific El Niño events in light inten-sity.The spatial distributions of precipitation anomalies of both them are less consistent.The precipitation anomaly in autumn flood season of Hainan Island is closely related to atmospheric circulation and water vapor transport.In the years with different types and intensities of El Niño events,the El Niño events can result in differences in response degrees of wind field,geopotential height field,sea-level pressure field,vertical velocity field,water vapor flux and divergence field by affecting the changes in the location and intensity of Walker circulation in varying degrees,which finally reduce the precipitation of Hainan Island in autumn flood season to different degrees.
El Niño Eventstypeintensityautumn precipitation in Hainan Island
万方数据
维普
