Impacts of North Atlantic sea surface temperature on the predominant modes of spring precipitation monthly evolution over Northeast China

Northeast China (NEC) is an important crop production base in East Asia. The monthly evolution of precipitation during spring sowing from April to May is of significance for agricultural activity and production over NEC. This study first investigates the predominant modes of April-to-May precipitation evolution over NEC and then explores their connections with North Atlantic sea surface temperature (SST) anomalies during 1979-2016. The first mode obtained using a multivariate empirical orthogonal function (MV-EOF1) shows an out-of-phase change in NEC precipitation anomalies from April to May, but the second mode (MV-EOF2) shows an in-phase change. Further analysis indicates that SST variability over mid-latitude North Atlantic (MNA) is related to MV-EOF1 by exciting a wave train from MNA to Eurasia. The wave train position is located more westward in May relative to April, leading to reverse atmospheric circulation and precipitation anomalies over NEC between April and May. The changes in position of circulations may be related to the westward shift of the North Atlantic storm track from April to May. MV-EOF2 is related to SST variability over northern tropical Atlantic (NTA). In April, NTA SST anomalies impact NEC precipitation through mid-latitude Eurasian wave train and Walker-like circulation anomalies between the Atlantic and Pacific Oceans. In May, the mid-latitude pathway is effective; however, the tropical pathway is significantly weakened, which may be related to the weakened intensity of NTA SST-induced tropical diabatic heating. Numerical simulations can reproduce the linkage between the North Atlantic SSTs and the pronounced atmospheric circulation anomalies in the observation, further confirming the impacts of North Atlantic SSTs on NEC April-to-May precipitation evolution.