Study on influence of SST anomaly on typical summer drought and flood in Changjiang River Basin
To study the characteristics of summer drought and flood in the Changjiang River Basin and its correlation with Sea Surface Temperature(SST)anomaly,based on the precipitation data of 326 meteorological stations in China and NCEP/NCAR re-analysis data,we adopted synthetic analysis and EOF decomposition to analyze precipitation,circulation and SST features in typi-cal drought and flood years in the Changjiang River Basin in summer and briefly revealed the possible influence of SST anomaly on atmospheric circulation at the early stage of 2018.The results indicated that:① when it came to the summer of a typical dry year in the Changjiang River Basin,only some regions in the Jialing River,Minjiang River,and Tuojiang River Basin suffered flood.China presented a typical Rain Pattern I with the rainy area located in the Yellow River Basin and its north.Moreover,in the early winter,the equatorial Pacific showed a La Nina-like distribution with low temperature in the Kuroshio area and warm SST in the westerly drift area.Due to the joint effects of different sea areas,the Eurasian circulation field presented a tripolar distribu-tion of"+-+"from northwest to southeast,and the East Asian region was a"-+-"EAP negative phase distribution from north to south.②2018 was a typical drought year in the middle and lower reaches of the Changjiang River,and the precipitation was nearly 30%more than normal only in the Minjiang River and Tuojiang River,which was the fourth most in history.Its mode was similar to the positive phase of the main summer precipitation mode in the Changjiang River Basin,and the explained variance was 24%.③ The SST anomaly distribution was attributed to the occurrence of weak La Nina in the early winter of 2018,the warmer SST in the west wind drift area,and the abnormal positive NAT from April to June.Due to the interactive effects of these three factors,the northerly Asia subtropical westerly jet moved north,East Asia Littoral showed a negative EAP,continental low pressure became stronger and the strongest East Asian monsoon since 1961 appeared.Moreover,the western Pacific subtropical high ridge moved to the northernmost,which led to the northward movement of the main rain belt to North China and Northwest China,the more abnormal precipitation in the Minjiang River and Tuojiang River and the Jialing River areas and less abnormal precipitation in the middle and lower reaches of the Changjiang River with a typical Rain Pattern I.The research results can pro-vide a reference and basis for drought and flood prediction and water resource scheduling in the Changjiang River Basin.
typical summer drought and floodSST anomalytypical type I rain beltLa Ninawest wind drift areaChangjiang River Basin
国家科技期刊平台
NSTL
万方数据
维普
