On wind-driven mid-latitude convection in ocean general circulation models

Several computational experiments were carried out with a state-of-the-art ocean general circulation model to identify the northward directed Ekman transport of antarctic and sub-antarctic origin surface water as a mechanism which forces mid-latitude convection. The results indicate that the wind-driven transport of water in the surface layer is most efficient at increasing thedepth of convection in the southeast region of the ocean basin investigated. To the north of thelatitude of maximum wind stress at about 50°S, a deepening of the convectively-mixed layer of more than 300 m is simulated if the wind forcing is doubled. In the real ocean, this identified mechanism of Ekman transport of cold and fresh water across the path of the antarctic circumpolar current may contribute to the formation of sub-antarctic mode water observed to thenorth of the sub-antarctic front of the southern ocean.