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Abstract:
The prevalence of supercooled Ice Shelf Water plumes carrying suspended frazil ice underneath the cold-water ice shelves is critically responsible for the marine ice production and the Antarctic Bottom Water formation in Antarctic. However, knowledge of these unique supercooled buoyant flows is still limited, let alone their vertical structure. Here we extended the vertical one-dimensional ice shelf–ocean boundary current (ISOBC) model from Jenkins (2016) by incorporating a frazil ice module and the k- turbulence closure. Based on that modified model, we reproduced the measured thermohaline properties of a perennially-prominent supercooled ISOBC underneath the Amery Ice Shelf, East Antarctica, and conducted sensitivity runs to a variety of factors, including advection of scalar quantities, far-field geostrophic currents, basal slope, and frazil ice size distribution. After that, following conclusions can be drawn: 1. the vertical structure of the ISOBC can be hardly reasonably reproduced by adopting a constant eddy viscosity/diffusivity near ice shelf base; 2. the size of the finest ice crystals plays an important role in controlling the ISOBC. 3. the vertical gradient of frazil ice concentration significantly reduces the level of turbulence within the ISOBC. Thus, this study highlights the importance of the strong interaction between the frazil ice formation and the ISOBC thermodynamics. This interaction must not only be included, but also be resolved at high resolutions in three-dimensional coupled ice shelf–ocean models applied to cold-water ice cavities.
