Title: Sea Ice Mechanics on the Surface of a Sphere using the Material-Point Method (MPM)

Abstract: Sea ice plays an important role in the global climate by reflecting solar radiation and influencing ocean circulation making it essential to accurately simulate sea ice dynamics in an Earth system model. In this talk we describe a new Material-Point-Method (MPM)-based discretization for sea ice being implemented within the Model for Prediction Across Scales (MPAS)-Seaice framework in the Energy Exascale Earth System Model (E3SM). The MPAS-SI-MPM model couples Lagrangian particles with an efficient mesh-based solution of the equations of motion. Lagrangian particle methods have certain advantages over Eulerian grid-based methods for sea ice modeling due to their ability to naturally handle advection, maintain a sharp ice edge, capture large deformations, and provide a framework for history-dependent material models, but require additional algorithms for locating the particles on the mesh and mapping values between the mesh and particles.  The salient feature of MPAS is the use of unstructured Voronoi meshes. The unstructured Voronoi meshes are Spherical Centriodal Voronoi Tesselations (SCVTs) which allow for both quasi-uniform discretization of the sphere and local refinement. To implement MPM within MPAS, MPM has been adapted to the spherical Voronoi mesh. We will describe our implementation, show that components of the algorithm converge as expected, and demonstrate performance on test cases.