期刊名称：Tellus A: Dynamic Meteorology and Oceanography
电子版ISSN：1600-0870
出版年度：2001
卷号：53
期号：1
页码：94-111
DOI：10.3402/tellusa.v53i1.12175
摘要：The physical processes responsible for the formation in a large-scale ice–ocean model of anoffshore polynya near the Greenwich meridian in the Southern Ocean are analysed. In thisarea, the brine release during ice formation in autumn is sufficient to destabilise the watercolumn and trigger convection. This incorporates relatively warm water into the surface layerwhich, in a first step, slows down ice formation. In a second step, it gives rise to ice meltinguntil the total disappearance of the ice at the end of September. Two elements are crucial forthe polynya opening. The first one is a strong ice-transport divergence in fall induced by southeasterlywinds, which enhances the amount of local ice formation and thus of brine release. Thesecond is an inflow of relatively warm water at depth originating from the Antarctic CircumpolarCurrent, that sustains the intense vertical heat flux in the ocean during convection. The simulatedpolynya occurs in a region where such features have been frequently observed. Nevertheless,the model polynya is too wide and persistent. In addition, it develops each year, contrary toobservations. The use of a climatological forcing with no interannual variability is the majorcause of these deficiencies, the simulated too low density in the deep Southern Ocean and thecoarse resolution of the model playing also a role. A passive tracer released in the polynya areaindicates that the water mass produced there contributes significantly to the renewal of deepwater in the Weddell Gyre and that it is a major component of the Antarctic Bottom Water(AABW) inflow into the model Atlantic.
