Influence of North Pacific SST on heavy precipitation events in autumn over North China

The characteristics of heavy precipitation occurrence in autumn (the month of September) over North China are investigated using daily observational data. Results indicate that heavy precipitation events experienced a significant decadal increase in 2000/2001. Further investigation reveals a close connection between heavy precipitation occurrence and simultaneous North Pacific SST. The SST anomaly over the North Pacific can result in intensification of the western North Pacific subtropical high and increased water vapor transport from the tropical ocean, which benefits the occurrence of heavy precipitation over North China. However, the key region of North Pacific SST influencing heavy precipitation events over North China was different in the periods 1960-2000 and 2001-2014, being located over the eastern Ocean to China in the first period but more eastward in the second period. This drift in the key region of SST is partly responsible for the decadal increase in heavy precipitation events over North China since 2000/2001. Additionally, the changes in SST variability (a decrease in the eastern Ocean to China and an increase to its east) may have been the main reason for the eastward movement of the key region in the latter period. Certainly, more work is needed in the future to verify the findings of this study.