Using the Material-Point Method in Earth System Modeling
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We present work on implementation of the material-point method (MPM) within MPAS-Seaice, the sea-ice core in the Department of Energy’s Earth System model, E3SM. E3SM uses the elastic-viscous-plastic rheology for sea ice which models ice as a continuous fluid with variable viscosity. The objective of this project is to improve the accuracy and reduce uncertainty in numerical predictions by improving the simulation of fluxes between the atmosphere, ice and ocean through an enhanced physical description of sea ice. The elastic-decohesive model is a solid model that has an explicit representation of fracture, accounting for lead opening and, for example, concomitant ice and dense water formation. Especially at high mesh resolutions, the improved physics and resulting ice dynamics using this model is expected to produce higher fidelity coupled Earth-system simulations. The elastic-decohesive constitutive model is implemented within MPM. MPM provides a Lagrangian description of the ice by embedding a set of material points within the mesh. Information about the solution, carried by the material points, is projected to the mesh where neeeded to solve the momentum equation. The momentum equation is then solved using the MPAS-Seaice solver with its multi-resolution mesh. The material points are then updated and moved by interpolating from the mesh solution. With MPM, the Lagrangian representation can be used where it has an advantage, eg. for advection and implementation of constitutive models, while the mesh-based representation is used to compute spatial gradients.
