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Abstract

It is thought that the primary mechanism driving the basal melting of Antarctic ice shelves is the intrusion of relatively warm circumpolar deep water (CDW) onto the continental shelf. However, the exact set of processes by which this happens – and the routes along which they occur - is often uncertain. The formation of dense shelf water (DSW) at the ocean-ice interface is a key factor in controlling the amount of heat that can cross the shelf break. Coarse resolution climate models struggle to explicitly resolve DSW due to its highly localised formation areas. We use an eddy-resolving formulation of MITgcm (SOHI), with 1/24^th degree horizontal resolution, 225 vertical levels and realistic bathymetry and sub-glacial cavities. We investigate DSW formation and CDW intrusion near the shelf using an OMP inversion to characterise water masses. Shelf regimes are classified and areas of high mixing that are important for heat transfer to the shelf are identified. We characterise the seasonality of these processes, showing the pathways that enable CDW to reach the shelf in summer when the slope front is weaker. OMP analysis of the 1/6^th degree Southern Ocean MITgcm model (SOSE) reveals that shelf water is more poorly represented at lower resolution. A lack of cavities and a coarser representation of bathymetry mean that SOSE also cannot simulate some of the topographically constrained pathways of CDW to the shelf. These results highlight the importance of model resolution for understanding and projecting future Antarctic melt rates.