Abstract
The transition between a grounded ice sheet and a floating ice shelf, the grounding line, is one of the most challenging transitions to model accurately in ice sheet models, yet processes there have a first-order control on ice sheet stability and associated sea level changes. The Marine Ice Sheet Model Intercomparison Project (MISMIP) is a series of community-developed and endorsed tests for grounding line dynamics and marine ice sheet modeling fidelity. MPAS-Land Ice (MPAS-LI) includes the Albany-Felix momentum balance solver developed under the SciDAC PISCEES project and has previously undergone extensive studies on formal verification, robustness, and scaling on HPC architectures. Newly completed results for the steady-state and transient MISMIP3D experiments using MPAS-LI demonstrate that (1) modeled grounding line positions exhibit first-order convergence as a function of grid resolution, and (2) model grounding line positions are consistent with those from previous models based on similar dynamics and physics. We thus propose that MPAS-LI “passes” the MISMIP3d test required to demonstrate realistic marine ice sheet dynamics. These results will allow us to confidently publish on the capabilities and performance of the new MPAS-LI model and, more importantly, are being used to guide the creation of variable-resolution meshes for realistic Antarctic Ice Sheet simulations.