Asymmetric effect of ENSO on the spring precipitation over East China

GONG Ting; YI Xiaoyuan

doi:10.19513/j.cnki.issn2096-3599.2023.04.005

Abstract：Using the observations and reanalysis datasets from 1958 to 2019,this study reveals an asymmetric effect of El Nino-Southern Oscillation(ENSO)on the following spring precipitation over East China.The results are listed as below.(1)During the years with positive ENSO phases,a strong positive correlation exists between the spring precipitation over Zhejiang and Jiangsu provinces and the preceding winter ENSO sea surface temperature(SST)anomalies.During the years with negative ENSO phases,such a strong positive correlation shifts westwards to inland areas,mainly in Jiangxi and Hunan provinces.(2)To be specific,the El Nino events usually result in a precipitation surplus in the decaying spring over Zhejiang,Jiangsu,and Fujian provinces,while the La Nina events usually lead to a precipitation deficit in the decaying spring over Jiangxi and Hunan provinces.This is attributed to the nonlinear effects of ENSO on the atmospheric circulation.(3)Compared with El Nino,the abnormal center of SST anomalies induced by La Nina evidently extends westwards,inducing a westward movement of the anomalous low-level atmospheric circulation,which eventually results in a westward-shifted effect on the following spring precipitation over East China.(4)The findings emphasize the nonlinear responses of the spring precipitation over East China to ENSO,which has important implications for the seasonal climate predictions over East China.