Modeling ice shelf cavities in the unstructured-grid, Finite Volume Community Ocean Model: Implementation and effects of resolving small-scale topography

An ice shelf module is implemented into the unstructured-grid, three-dimensional primitive equation Finite Volume Community Ocean Model (FVCOM) for studying ice shelf-ocean interactions along the complex and irregular geometry of the coastal ocean. Pressure gradient errors associated with the representation of the ice shelf geometry in the model’s terrain-following vertical coordinate are investigated, showing that locally increasing resolution efficiently reduces spurious currents near the steeply sloping grounding lines and ice fronts. Simulated basal melting and cavity circulation are compared within the framework of the on-going 2nd Ice Shelf Ocean Model Intercomparison project (ISOMIP+). Sensitivity studies are carried out, showing that the melt rate magnitude and distribution depends on properly resolving the slope at the ice base in combination with the choice of vertical mixing scheme. Idealized geometry simulations show that local effects of small-scale topographic features at the ice base may dominate the melt rate distribution and buoyancy fluxes that drive the circulation inside the ice shelf cavity.