Marine Heatwaves in the seas around Korea: Seasonal differences

Abstract

The seasonal and regional changes of marine heatwaves (MHWs) in the seas around Korea were investigated using the daily Optimum Interpolation Sea Surface Temperature for 37 years (1982– 2018). The summer MHWs occur 54% more frequently (2.7 events/decade) in a relatively wide area than in other seasons. The strong (up to 3.7 deg. C) and long-lasting (up to 38 days/event) winter MHWs are concentrated along the subpolar front (SPF) in the East/Japan Sea (EJS) where the MHWs are 20% longer (2.2 days/event) than in the Yellow and East China Seas (YECS). The summer MHWs are primarily driven by increased shortwave radiation associated with reduced cloud cover and latent cooling from the weakened wind over the western ëank of developing subtropical highs. The driving mechanisms of the winter MHWs diéer by region. In winter, the YECS MHWs occur mainly due to the atmospheric processes associated with weakening continental highs, while the EJS MHWs are largely driven by the northward shift of the SPF. Although large-scale atmospheric processes primarily drive the summer MHWs in the seas around Korea, our êndings suggest that ocean processes including ocean currents can be signiêcant contributors to intensiêed MHW occurrence in limited areas, especially in winter.