Pathways of mesoscale variability in the South China Sea

The propagation of oceanic mesoscale signals in the South China Sea(SCS) is mapped from satellite altimetric observations and an eddy-resolving global ocean model by using the maximum cross-correlation(MCC) method.Significant mesoscale signals propagate along two major bands of high variability.The northern band is located west of the Luzon Strait,characterized by southwestward eddy propagation.Although eddies are the most active in winter,their southwestward migrations,steered by bathymetry,occur throughout the year.Advection by the mean flow plays a secondary role in modulating the propagating speed.The southern eddy band lies in the southwest part of the SCS deep basin and is oriented in an approximately meridional direction.Mesoscale variability propagates southward along the band in autumn.This southward eddy pathway could not be explained by mean flow advection and is likely related to eddy detachments from the western boundary current due to nonlinear effects.Our mapping of eddy propagation velocities provides important information for further understanding eddy dynamics in the SCS.