Submesoscale eddies in the South China Sea

Submesoscale eddies are often seen in high‐resolution satellite‐derived ocean colour 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 (SCS). 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.