Submesoscale Eddies in the South China Sea

Submesoscale eddies are often seen in high-resolution satellite-derived ocean color images. To efficiently identify these eddies from surface chlorophyll data, here, we develop an automatic submesoscale eddy detection method and apply it to the South China Sea. The detected submesoscale eddies are found to have a radius of 13 +/- 5 km and an aspect ratio of 0.5 +/- 0.2, with a notable predominance of cyclones. Further investigation reveals that the surface structure of these eddies displays a unique cat's-eye pattern, and the eddies become more circular with increasing eddy radius. Submesoscale eddies can strongly regulate surface chlorophyll via horizontal advection while they have less coherent signatures in sea surface temperature. These findings may help to improve submesoscale parameterizations in Earth system models.

Automated summary

An automatic detection method for submesoscale eddies in the South China Sea is developed, revealing their characteristics of an average radius of about 13 km and an aspect ratio of 0.5, with a predominance of cyclones. Additionally, the unique cat's-eye pattern on the surface and the tendency for eddies to become more circular with increasing radius are observed. Submesoscale eddies strongly regulate surface chlorophyll through horizontal advection, while having less coherent signatures in sea surface temperature.