Thermohaline Suppression of Upper Circumpolar Deep Water Eddies in the Ross Gyre

Temperature and salinity measurements of a warm-core eddy at the northern flank of the Ross Gyre are analyzed for dominant mixing mechanisms. The eddy is centered at the depths of the Circumpolar Deep Water and carries heat towards the gyre. Vertical and horizontal heat fluxes out of the eddy associated with internal wave turbulent mixing and thermohaline intrusions are estimated. Upward internal wave turbulent heat flux is O(100) W/m2, whereas, the lateral intrusive heat flux is of the order of O(1000) W/m2. The horizontal flux due to intrusions is suggested to be the dominant mechanism for eddy decay and yields an eddy lifetime of about 6 months. The thermohaline intrusion-eddy suppression mechanism is proposed and shown to be effective in suppressing the eddy field at the northern flank of the Ross Gyre. This effect has important implications for setting the basin-wide heat budget and regulating sea-ice cover.