Projected intensification of summer upwelling along the Southeastern Coast of China

Coastal upwelling is a key dynamical process along the southeastern coast of China, regulating regional circulation, biogeochemical cycling, and marine ecosystem dynamics. While previous studies have provided valuable insights into the mechanisms and variability of this coastal upwelling, its future evolution and underlying physical drivers under climate change remain unclear. Here, we investigate projected changes in coastal upwelling along the southeastern coast of China during 2006–2100 using a high-resolution (0.1°) coupled-model realization under the Representative Concentration Pathway 8.5 scenario. During 2006–2100, the area-weighted mean oceanic vertical velocity at 30 m increases at 0.755 m day -1 century -1 , while the upwelling area increases at 1.822 × 10³ km² century -1 . The trend in the total upwelling volume transport is approximately 0.27 Sv century -1 . Enhanced Ekman transport makes the largest contribution (0.26 Sv century -1 ), accompanied by a geostrophic-transport trend of 0.07 Sv century -1 . Marine heatwave (MHW) metrics based on local linear detrended SST are generally lower at the selected coastal sites than at offshore sites, with an 18.3% reduction in MHW days, a 33.2% reduction in mean annual duration, and a 2.4% reduction in mean cumulative intensity. These coastal–offshore contrasts are to some extent consistent with a potential moderating influence of upwelling on MHWs, though rigorous attribution and mechanistic analyses of this effect remain open for dedicated future investigations. This study can advance our understanding of ocean dynamics along the southeastern coast of China under future climate change.