On the Relationship between Springtime Droughts and Floods in Southern China and Sea Surface Temperature

PENG Yao; TAN Yong-zhan; PENG Jing-hong; HE Bin; TAN Hao-yu

doi:10.3969/j.issn.1007-6190.2023.06.006

Abstract：Based on the annual standardized precipitation evapotranspiration index(SPEI)for the springs from 1961 to 2016 in southern China and with the methods of correlation analysis and singular value decomposition(SVD),this work discussed the relationship between the droughts and floods in the spring of southern China and the sea surface temperature(SST)and tested the linkage between the proceeding winter SST and the springtime droughts and floods in southern China for the years 2017 to 2021.The results are shown as follows.(1)When the SST keeps anomalously cool over tropical central and eastern Pacific,grad-ually turns anomalously cool in the South China Sea,the Malay archipelago and waters off the western North America,and gradually gets anomalously warm in central North Pacific and equatorial western Pacific in the proceeding winter and the current spring,the eastern part of southern China will be anomalously dry in the spring,and otherwise is true.When there is a La Ñina(El Ñino)episode in the proceeding winter and the current spring,the eastern part of southern China is likely to experience droughts(floods)in the spring,and the Pacific ENSO has persistent and important effect on the variation of droughts and floods in this re-gion,suggesting an increasing role by the Pacific Dipole Oscillation(PDO)in this regard.A cold(warm)phase of the PDO is favorable for droughts(floods)to take place in this region.(2)When the SST keeps a-nomalously warm over the Indian Ocean,tropical Pacific,the Gulf of Alaska and tropical Atlantic,it will be anomalously dry in western,central and southern Guangxi as well as the Leizhou Peninsula in the spring,and otherwise is true.(3)It is known from tests on the linkage between proceeding winter SST and spring-time droughts and floods in southern China for the years 2017 to 2021 that typical wintertime SST distribu-tions(such as those in 2017,2020 and 2018)can be used to predict whether southern China will experi-ence a drought or a flood in the spring.