A model for the spreading and sinking of the Deep Ice Shelf Waterin the Ross Sea

[摘要] Spreading and sinking of the Deep Ice Shelf Water (DISW) in the Ross Sea are analysed usingin situ observations and the results of a nonlinear, reduced gravity, layered numerical model, which is able tosimulate the motion of a bottom trapped current over realistic topography. The model is forced byprescribing thickness and density of the DISW layer at the southern model boundary as well as ambientdensity stratification above the DISW layer. This density structure is imposed using hydrographic dataacquired by the Italian PNRA-CLIMA project. In the model water of the quiescent ambient ocean is allowedto entrain in the active deep layer due to a simple entrainment parameterization. The importance of forcingthe model with a realistic ambient density is demonstrated by carrying out a numerical simulation using anidealized ambient density. In a more realistic simulation the path and the density structure of the DISW veinflowing over the Challenger Basin are obtained and are found to be in good agreement with data. It is foundthat entrainment, which is particularly active in regions of strong topographic variation, significantlyinfluences the pattern followed by the DISW layer. The evolution of the DISW layer beyond the continentalshelf, i.e., in a region where the paucity of experimental data does not allow for a detailed description of thedeep ocean dynamics, is also investigated.

[学科分类] 自然科学（综合）