On the Relationship between Earlier-than-usual Onset of the 2023 Rainy Season in Southern China and General Circulation and Sea Surface Temperature
By using the methods of composite and correlation analysis and diagnosing relevant physical quantities,this paper analyzed the characteristics of the general circulation and sea surface temperature(SST)for the 2023 rainy season in southern China that started earlier than usual and against the background of triple La Niña episodes.They were then compared with the case of 2022.The results are shown as fol-lows.(1)In Marches 2022 and 2023,it rained relatively more in Guangdong province,which was correla-ted with relatively warm SST in North Pacific in the winters that just passed.Rainy seasons started earlier than usual in southern China in the two years of interest,as they were respectively related with high SST in waters of the central Indian Ocean ridges and off the east of the eastern Pacific dunes in the previous winters.(2)In Marches 2022 and 2023,850-hPa wind fields were anticyclonically distributed in the coastal waters of southern China where southwesterly and southerly air flows overland were favorable for the transport of wa-ter vapor.The earlier-than-usual onset of the rainy season in both of the years were related with the southward movement of cold air.(3)In Marches 2022 and 2023,the northern ascending branch of a local Hadley cell in southern China strengthened over the equatorial region while the northward descending branch weakened and retreated southward,showing negative anomalies in the range from 0°N to 20°N,being con-ducive for the precipitation to increase over Guangdong in Marches 2022 and 2023.
synopticsonset of rainy seasonsea surface temperaturegeneral circulationSouthern China
万方数据
维普
