Bias of ENSO-like SST breaks the connection between the North Atlantic SST and Northeast China spring precipitation in the NCEP CFSv2

This study investigates the prediction bias of the relationship between northern tropical Atlantic (NTA) sea surface temperature (SST) and Northeast China spring precipitation (NECSP) based on the hindcast and forecast dataset initialized in February from the NCEP Climate Forecast System, Version 2 (CFSv2). In the observation, spring NTA SST warming excites a negative phase North Atlantic Oscillation-like (NAO-like) pattern, which further induces cyclonic anomalies over Northeast Asia and increases NECSP through a Eurasian midlatitude wave train. The CFSv2 prediction generally captures the negative NAO-like response to NTA SST warming but fails to reproduce the downstream Eurasian wave train, further resulting in weak atmospheric circulation anomalies over Northeast Asia. Therefore, CFSv2 cannot predict the NTA SST-NECSP relationship. The prediction bias in the NTA SST-NECSP relationship could be due to CFSv2 exaggerating the connection between the NTA SST and ENSO-like SST over the tropical Indo-Pacific because of its overestimation of the ENSO amplitude. The El Nino-like SST induces high pressure over midlatitude East Asia in both the observation and prediction. With the overestimated relationship between the NTA SST and tropical Indo-Pacific SSTs, the NTA SST warming-induced low pressure over Northeast Asia could be overwhelmed by the high pressure induced by El Nino-like SST. After excluding the influence of ENSO-like SST, the NTA SST-related anomalous circulation pattern over the North Atlantic-Eurasia region shows a high similarity between the observation and prediction. Furthermore, a hybrid dynamic-statistical prediction model is established based on CFSv2-predicted atmospheric circulations to improve NECSP prediction.