Statistics on the Cross-Slope Propagation of Mesoscale Eddies in the Northern South China Sea

Abstract The generation, propagation, and dissipation of mesoscale eddy in the South China Sea (SCS) play an important role in the local mass and momentum transports, and climate changes, where the cross-slope transport of the mesoscale eddies is one of the most important manners of water exchange between the deep sea and continental shelf in the northern South China Sea, involving multiple-scale ocean dynamic. This study focuses on the cross-slope propagation of mesoscale eddies in the northern South China Sea and investigates the physical processes of the demise of these eddies on the slope topography, and then the differences in cross-slope propagation and demise of the anticyclonic eddy (AE) and cyclonic eddy (CE) are analysed using the satellite altimeter data over the period 1993-2022. The satellite observations show that total of 533 mesoscale eddies are generated locally in the northern SCS in the past 30 years, where the number of the AE and CE is comparable. The eddy propagation and dissipation exhibit the AEs are more likely to cross the slope than the CEs, whereas the number of CEs dissipated in the slope region is conversely more than that of AE. Moreover, the average lifespan, radius, amplitude, and EKE of the cross-slope eddies are all larger than the non cross-slope eddies. These findings improve our understanding of eddy-topography dynamics in the northern South China Sea.