Influence of Typhoon Hinnamnor–induced near-inertial gravity waves on the suppression of marine heatwave

Abstract Anthropogenic climate change has increased interactions between typhoons and marine heatwaves (MHWs) worldwide. Typhoon Hinnamnor (2022), which originated in the northwestern Pacific and weakened over the East Sea, demonstrates this interaction. While previous studies have explored typhoon intensification due to underlying MHWs, the formation of MHWs following a typhoon’s passage remains less understood. Post-typhoon MHWs can form due to local ocean heat uptake by anomalously cold sea surface temperatures overlying an anomalously warmer subsurface. This study provides the first detailed analysis of MHW formation on the west side of a typhoon path, off Korea’s east coast, approximately one week after the typhoon, using data from a fixed surface mooring. The results indicate that near-inertial internal gravity waves, influenced by sub-inertial background conditions, prevented the onset of the MHW during the week following the typhoon’s passage, despite favorable conditions such as coastal downwelling, increased surface net heat flux, and higher upper-ocean heat content.