Ocean-Ice Shelf Interactions in the Accelerated Climate Model for Energy (ACME)

The Accelerated Climate Model for Energy (ACME), a new initiative by the U.S. Department of Energy, includes unstructured-mesh ocean, land-ice, and sea-ice components using the Model for Prediction Across Scales (MPAS) framework. The ability to run coupled high-resolution global simulations efficiently on large, high-performance computers is a priority for ACME.

We are coupling the MPAS-Ocean the MPAS-Land-Ice models to better understand how changing ocean temperature and currents influence glacial melting and retreat. These simulations take advantage of the horizontal variable-resolution mesh and adaptive vertical coordinate in MPAS-Ocean, in order to place high resolution below ice shelves and near grounding lines. MPAS-Ocean has been tested with compressed vertical coordinates and melt fluxes below ice shelves in idealized test cases such as the first and second Ice Shelf-Ocean Model Intercomparison Projects (ISOMIP and ISOMIP+), the Marine Ice Sheet-Ocean Model Intercomparison Project (MISOMIP), and realistic global ocean cases. The ability to represent moving grounding lines is a difficult challenge and an area of active research. Solutions include grounding line parameterizations, high horizontal and vertical resolution, and wetting and drying of ocean cells. We compare idealized results with those from other ocean models and melt rates from our realistic simulations with those inferred from satellite observations.