Physical Causes of Significant Spring Marine Heatwaves in the Yellow and East China Seas During 1982–2018

Abstract During 1982–2018, eight significant spring marine heatwave (MHW) events occurred in the Yellow and East China Seas (YECS), each lasting 15–63 days. Anomalous descending motions and anomalous surface winds were the main local drivers of these MHWs. Anomalous descending motions increased incident shortwave radiation, and anomalous surface winds reduced oceanic latent heat loss and shoaled the mixed layer (ML). The resultant positive net surface heat flux ( Q ) anomalies directly warmed the ML, driving MHWs. In addition, the shoaled ML amplified the warming effects of both positive Q anomalies and positive climatological mean Q . Positive Q anomalies could also indirectly contribute to MHWs by shoaling the ML. Further analyses identified four types of large‐scale atmospheric drivers that were important to these spring MHWs. Westward extension of the northwestern Pacific subtropical high and enhanced convection in the Indian Ocean and the Maritime Continent triggered the MHWs in the southern East China Sea (ECS). Atmospheric wave trains from the North Atlantic to the YECS played important roles in causing MHWs in the Yellow Sea and the northern ECS. Furthermore, enhanced atmospheric latent heating in the northern South China Sea and the subtropical northwestern Pacific supported the MHW around the boundary between the Yellow Sea and the ECS. These findings highlight key physical predictors that can improve the forecasting of YECS spring MHWs.