A study of the cyclonic eddy shedding phenomenon in the Agulhas Return Current

Abstract

The detachment of the cyclonic eddy (CE) from the mainstream on the north side of the Agulhas Return Current (ARC) is first observed and analyzed with a multiparameter eddy dataset and eddy detection technique. It is found that there exists a special form (ACA) of two anticyclonic eddies (AE) sandwiching a cyclonic eddy (CE). The cyclonic eddy is then locally shed from the jet and shifts to the west before finally being recaptured by the mainstream. From observations, cyclonic eddy detachments in ACA form can be classified into two categories based on the detachment mode and on the sea surface height (SSH) data. Using reanalysis data, satellite observation data and Argo data, the analysis reveals that the positional relationship between the anticyclonic eddies and cyclonic eddy affects the detachment type. In addition, the existence of the ARC itself, with its giant meandering morphology and dissipative effect, also provides conditions for the detachment of the cyclonic eddy.