Teleconnection patterns impacting on the summer consecutive extreme rainfall in Central-Eastern China

摘要

Consecutive extreme rainfall (CER) events can cause enormous damage to human society and the environment in eastern China. This study analyses persistent atmospheric circulation patterns related to dominant CER modes over Central-Eastern China. Results reveal that the two leading modes together explain 30 of the total CER variance. The circulation patterns related to the first CER mode manifest a barotropic Eurasian (EU) pattern teleconnection 4 days before the CER events occur in the southern Yangtze River. The second CER mode is associated with a negative Pacific-Japan (PJ) teleconnection pattern, which persists for 5 days until the onset of CER events in the Yangtze River Valley. Furthermore, the stagnant double blocking highs around the Urals and the Sea of Okhotsk and the vapour transport from the western North Pacific (WNP) distinguish the persistent circulations of the second CER mode from the firstmode. Therefore, the configuration of persistent circulation patterns is likely responsible for the occurrence of CER events. Further analysis suggests that the Rossby waves, in association with dipolar sea surface temperature (SST) anomalies in the northeastern Atlantic, propagate eastward towards East Asia, generating an EU-like teleconnection 4 days prior to CER event onset. Furthermore, cold SST anomalies in the warm pool and warm SST anomalies in the tropical WNP-South China Sea and the western Indian Ocean induce poleward-propagating Rossby waves, creating a negative PJ teleconnection pattern up to 5 days prior to CER events. These results are supported by ray paths originating from base points of EU and PJ teleconnections.