Impacts of non-canonical Atlantic Ni?o on eastern China precipitation in the early and late rainy seasons
Exploring the potential predictability of seasonal precipitation in Eastern China beyond the preceding winter El Niño-Southern Oscillation(ENSO)has long been a significant challenge.This study investigates the in-fluences of the non-canonical Atlantic Niño(NCA)on precipitation patterns in Eastern China during the early and late rainy seasons using observational and reanalysis data from 1979 to 2020.Results indicate that the NCA leads to increased precipitation in southern China during the early rainy season,while it decreases precipitation a-long the southern coast but increases precipitation in northern China during the late rainy season.This is because,in the early rainy season,warm sea surface temperature(SST)anomalies associated with the NCA in the North Tropical Atlantic trigger La Niña through the"wind-evaporation-SST"feedback,inducing an anomalous anticyclone over the western North Pacific.The southwesterly flow along the northwest flank of this anomalous anticyclone transports warm and moist air into southern China,resulting in increased precipitation.Con-versely,during the late rainy season,NCA-related warm SST anomalies migrate southward to the equatorial Atlan-tic,modifying the Walker circulation,reinforcing La Niña,and intensifying the anomalous anticyclone over the western North Pacific.This enhanced anticyclone covers the southern coastal region of China,reducing precipitation there,while further northward moisture transport along the enhanced anticyclone increases precipitati-on in northern China.Additionally,NCA influences Eastern China's precipitation by stimulating different mid-high-latitude Rossby waves in the early and late rainy seasons.In the early rainy season,the Rossby wave is primarily triggered by a-nomalous warm SST in the North Tropical Atlantic,propagating from northern Africa to the Qinghai-Tibet Plateau and eventually reaching the Yangtze River basin.Although the SST anomalies in the Tropical North Atlantic weaken during the late rainy seasons,the North Atlantic Oscillation can still strengthen through local air-sea cou-pling,thereby developing SST in the North Atlantic.The Rossby wave,induced by an anomalous SST in the North Atlantic,across the Eastern European Plain,the Siberian Plain,and Lake Baikal,propagates southeastward to northern China,forming an anticyclonic anomaly in the upper troposphere and facilitating precipitation in northern China.This study reveals distinct seasonal variations in NCA-related precipitation anomalies in Eastern China,high-lighting the complexity of large-scale circulation responses to the NCA.It provides a vital scientific basis for im-proving precipitation forecasting and early warning systems in China.Further investigation is needed to determine the extent to which numerical models can simulate NCA and its teleconnections.
Non-Canonical Atlantic Niño(NCA)eastern Chinaearly and late rainy seasonprecipitation
万方数据
维普
