Cross-Slope Heat and Salt Transport Induced by Slope Intrusion Eddy's Horizontal Asymmetry in the Northern South China Sea

Material transport caused by mesoscale eddies has been revealed much in the open ocean; however, it is still unclear how much eddy-induced mass transport in the slope region of the northern South China Sea (SCS). Using the LASG/IAP Climate System Ocean Model (LICOM) from 2007 to 2017, we identified 47 anticyclonic eddies and 97 cyclonic eddies that intruded onto the continental slope, termed slope intrusion eddies. The slope intrusion eddies are more horizontally asymmetric and energetic than those without entering the slope. These eddies induced cross-slope heat and salt transport of O (10(12)) W and O (10(4)) kg s(-1) owing to their horizontal asymmetry in both Xisha Islands and Dongsha Islands, where are the intrusion zones of mesoscale eddies. Based on the potential vorticity budget, we found that the horizontal asymmetry of velocity was caused by the asymmetry of potential vorticity, which was mainly generated by eddy-current nonlinear effect in the Dongsha Islands and topographic beta effect in the Xisha Islands, respectively. This study may promote our understanding on the mesoscale dynamics and oceanic energy redistribution in the continental shelf zone of marginal sea.

Automated summary

This study reveals the presence of slope intrusion eddies in the slope region of the northern South China Sea, which have significant horizontal asymmetry and induce cross-slope heat and salt transport. The horizontal asymmetry of these eddies is mainly caused by eddy-current nonlinear effect in the Dongsha Islands and topographic beta effect in the Xisha Islands.