Horizontal velocity structure of mesoscale eddies in the South China Sea

The horizontal velocity structure of mesoscale eddies is investigated using data from 18-year altimetry data in the South China Sea (SCS). A total of 2,433 cyclonic eddies (CEs) and 3,132 anticyclonic eddies (AEs) are detected in this data set This analysis shows that the eddy velocity structure is strongly linked to the eddy amplitude, with the band of maximum velocity moving closer to the eddy core as the eddy amplitude increases. By combining the records of Argo float profiles and satellite altimetry data, the eddy feature found in sea level anomaly (SLA) data can also be seen at the subsurface. This feature is related to sub-mesoscale processes accompanying with water exchange and energy cascade at the outer edge of mesoscale eddy. A modified Taylor vortex model is built including this new finding to describe the eddy velocity structure. This vortex model is found to be useful as it better describes the eddy's life history, the knowledge of which is important for better understanding physical, biological and chemical processes in the ocean.