Delayed baroclinic response of the Antarctic circumpolar current to surface wind stress

Abstract

Antarctic Circumpolar Current (ACC) responds to the surface windstress via two processes, i.e., instant barotropic process and delayed baroclinic process. This study focuses on the baroclinic instability mechanism in ACC. That is, the strengthening of surface zonal windstress causes the enhanced tilting of the isopycnal surface, which leads to the intense baroclinic instability. Simultaneously, the mesoscale eddies resulting from the baroclinic instability facilitate the transformation of mean potential energy to eddy energy, which causes the remarkable decrease of the ACC volume transport with the 2-year lag time. This delayed negative correlation between the ACC transport and the zonal windstress may account for the steadiness of the ACC transport in these two decades.