Influence of developing phase of El Niño events on summer extreme precipitations in eastern China

Re-analysis data and precipitation dataset from 1961 to 2020 were used in this paper to analyze the influence of developing phase of Eastern Pacific El Niño events on summer extreme precipitations in China． It was found that during the developing summer, El Niño mainly affected eastern China, resulting in extreme precipitations in Northern China． Extreme precipitations decreased in the Jiangnan region, but increased significantly in the Jianghuai region． Physical process analysis revealed that when Eastern Pacific El Niño event is in the developing summer, significant positive SST anomalies were observed in the equatorial Eastern Pacific and negative SST anomalies were observed in the Western Pacific, which are associated with anticyclonic circulation anomalies． There were positive SST anomalies in the Northwest Pacific, corresponding to cyclonic circulation anomalies． Anomalous SST stimulated “+ - +” EAP wave train anomalies and caused “- + -” precipitation configuration． At the intersection of anomalous circulations, it showed a significant anomalous convergence and ascent, which brought sufficient water vapor to the Jianghuai region． Northern China was mainly controlled by anticyclonic circulation and Mongolian high, however, affected by anomalous northwest wind at high latitudes． There was significant anomalous divergence and sinking, the dynamic conditions of precipitation were insufficient． During the developing phase of Eastern Pacific El Niño events, the Western Pacific subtropical high shifted eastward, which weakened the occurrence of precipitation and water vapor transport in Jiangnan region, resulting in decreased extreme precipitations in Jiangnan region． These results highlight the important impact of Eastern Pacific El Niño events on extreme precipitations in China during the developing summer, and provide a theoretical basis for regional extreme climate prediction．