Heavy Southern China Spring Rainfall Promoted by Multi-Year El Nino Events

Southern China spring rainfall (SCSR) is significant for agricultural sowing and soil moisture accumulation before the rainy summer. A better prediction of the rainfall improves our ability to risk response to natural disasters. It is found that the SCSR can be promoted by multi-year El Nino events through the high-latitude pathway (HP) and low-latitude pathway (LP). The long-lasting El Nino warming heats the tropical troposphere persistently until the decaying spring, which strengthens the Arctic polar vortex and the mid-latitude blockings. This HP is in favor of more southward transport of Rossby wave energy and cold air, resulting in strong ascending motions over southern China (SC) in spring. The multi-year El Nino also induces an enhanced western North Pacific anticyclone and a secondary circulation transporting moisture to SC through the LP. The HP is more important in the early spring, while the LP dominates the heavy SCSR in the late spring.