Coupling of Mesoscale Eddies in the Antarctic Circumpolar Current to the Overlying Atmosphere

Mesoscale meanders and eddies over the extratropical global ocean are observed influencing the overlying atmosphere when examined in satellite sea level height (SLH), sea surface temperature (SST), and neutral surface wind (NSW) from June 1999 to June 2001. These eddies propagate according to baroclinic Rossby wave dynamics. Throughout the year, covarying high (low) SLH and warm (cool) SST residuals in the eddies drive eastward (westward) NSW residuals directly overhead through their influence on the stability of the planetary boundary layer, altering the surface winds stress associated with background westerly winds. The resulting feedback from atmosphere to ocean acts through a SLH tendency forced by wind stress curl (WSC) residuals. In the western boundary extension currents and intense portion of the Antarctic Circumpolar Current, this WSC feedback is too weak to alter the relatively strong eddies, but over most of the remainder of the extratropical global ocean, the WSC feedback is significant, coupling the mesoscale eddies to the atmosphere. A coupled Rossby wave model is constructed, yielding coupling phase velocities which explain specific aspects of observed phase velocities over the extratropical global ocean.