Increased Role of Late Winter Sea Surface Temperature Variability Over Northern Tropical Atlantic in Spring Precipitation Prediction Over Northeast China

摘要

The present study investigates the relationship between the winter North Atlantic sea surface temperature (SST) and spring Northeast China (NEC) precipitation during 1961-2016 from a seasonal prediction aspect. The results show that the February SST variability over the northern tropical Atlantic (NTA) has an enhanced relationship with the spring NEC precipitation after the late 1970s,consequently providing a prediction source for the spring NEC precipitation during the period. Such an interdecadal change in the relationship between February NTA SST and spring NEC precipitation is associated with the interdecadal change in the tropical SST around the late 1970s. The NTA SST exhibits good persistence from late winter to spring. Under the warmer SST background after the late 1970s, the NTA SST is related to more active tropical convection and diabatic heating anomalies in spring, consequently leading to an enhanced connection between the NTA SST and atmospheric circulations over the middle-to-high latitude North Atlantic during the period. Anomalous atmospheric circulations over the North Atlantic can further excite Rossby wave train that propagates eastward to East Asia, consequently influencing the moisture and dynamic conditions over NEC. Through the aforementioned physical processes, the NTA SST variability can lead to anomalous precipitation over NEC. The physical processes linking the NTA SST anomalies and spring NEC precipitation are further confirmed by an atmospheric general circulation model experiment forced with idealized NTA warming. The 1-month lead information of the NTA SST provides a prediction source for spring precipitation over NEC, which has potential usage in operational forecasting.