Influence of South China Sea warming on winter precipitation in Southern China via three-dimensional atmospheric circulation bridge

The winter precipitation in southern China (SC) typically displays a negative anomaly during La Niña events. However, the precipitation anomaly in SC showed inverse distribution in the winter of 2020/21 and 2021/22 when La Niña conditions prevailed. Negative precipitation anomaly was observed during the winter of 2020/21, whereas a distinct pattern of positive precipitation anomalies appeared during the winter of 2021/22. This abnormal phenomenon prompts us to explore why there were positive precipitation anomalies in SC under the background of La Niña. The results show that the sea surface temperature (SST) in South China Sea (SCS) can modulate winter precipitation in SC, excluding the influence of La Niña. To clarify the physical processes, by utilizing the three-pattern decomposition of global atmospheric circulation (3P-DGAC), the three-dimensional atmospheric circulation bridge was established between the SST in SCS and winter precipitation in SC effectively. The positive SST anomalies in SCS trigger local anomalous anticyclone, transporting massive water vapor to SC. Meanwhile, the local meridional and zonal circulations related to SST warming in SCS favor abnormal updraft flow over SC, which are conducive to the strengthening of convective potential. Overall, the three-dimensional atmospheric circulation induced by the SST warming in SCS contributes significantly to the increment of winter precipitation in SC. Besides, the predicted results of BCC_CSM1.1 (m) model emphasized the important role of the SST in SCS on the winter precipitation in SC. Our findings suggest that the SST in SCS might provide a viable source for advancing the regional seasonal climate prediction.