Ice production and convective mixing in the coastal polynya off Lutzow-Holm Bay, Antarctica

Abstract

A coastal polynya often forms around Lutzow-Holm Bay even in severe winter. To clarify the characteristics of oceanic structure in the polynya, the water mass of the convective-mixed layer was analyzed. Haline convection by the high ice production in the winter polynya contributes to the formation of a thicker mixed layer than that in the pack ice region. Furthermore, the active convection leads to entrainment of the oxygen-poor deep water underlying the winter mixed layer. Consequently, in the polynya located over the continental shelf break, the oxygen content of the mixed layer is somewhat lower than that in the other polynya, Breid Bay, where haline convection reaches only to the shallow sea bottom of the continental shelf.