CLARION

The CLARION project aims at improving the understanding of ice sheet-ocean interactions in the Antarctic region through a series of large-scale regional simulations of interactions between the Antarctic Ice Sheet and the Southern Ocean. A major focus of the project is the continued development of the POPSICLES ice sheet-ocean model, one of the first coupled ice sheet-ocean models and and the first to perform large-scale, high resolution circum-Antarctic simulations. POPSICLES is the coupling of the Parallel Ocean Program (POP) and the Berkeley Ice Sheet Model (BISICLES). Our POPSICLES simulation results have shown that melt rates, and thus ice-sheet advance and retreat, are strongly sensitive to climate forcing. Changes in heat and salt fluxes at the ocean surface can lead shallowing or deepening of the surface mixed layer, which affects whether or not warm, deep water (such as Circumpolar Deep Water) reaches ice shelves. We have also shown that uncertainties in the topography of the Antarctic Ice Sheet (AIS), particularly in the bedrock topography below ice shelves, add to the difficulties in both present-day modeling and projections of the of the AIS. Our simulations show an instability toward advancing ice in regions where bedrock topography is unknown and sub-ice-shelf cavity is assumed to be thin. In collaboration with the ice-sheet modeling group of Prof. Anders Levermann, melt rates from POPSICLES simulations will also be used as boundary conditions for Antarctic simulations with the Parallel Ice Sheet Model (PISM). CLARION also involves development of ice sheet-ocean interactions in a second ocean model, the Model for Prediction Across Scales Ocean (MPAS-O). The goal of this portion of the project is to transition toward ice sheet-ocean coupling in an earth system model (ACME: the Accelerated Climate Model for Energy). Under CLARION, we are adding the sub-ice-shelf boundary-layer physics to MPAS-O and performing testing in idealized configurations. Part of this work is the development of a new set of idealized, coupled tests called the Marine Ice Sheet-Ocean Model Intercomparison Project (MISOMIP).