Title: Modeling Arctic Sea Ice Using the Material-Point Method Speaker: Kara Peterson, University of New Mexico Date/Time: May 14, 2008 at 9:00 - 10:00am Location: CSRI Building, Room 90 (Sandia NM) Brief Abstract: Arctic sea ice is composed of a series of interacting floes separated by leads or areas of open water. The deformation of the ice is driven by ocean currents and surface winds, which can cause the leads to open, shear, or close and compress to form thick ridges of ice. Seasonally, the ice grows and melts in response to incoming solar radiation and thermal radiation from the atmosphere. A complete model for sea ice must combine a dynamic component to calculate deformation and a thermodynamic component to calculate ice growth and melt. Since both components depend on ice thickness, they are typically combined using an evolution equation for an ice thickness distribution. Historically, the momentum equation that defines the dynamic response of the sea ice and the horizontal advection equations resulting from the discretization of the ice thickness distribution in thickness space have been solved numerically using Eulerian schemes. These schemes have the advantage of accomodating large deformations, but introduce numerical diffusion when used to solve advection equations. Much effort in the ice modeling community has been spent in developing methods that limit this numerical diffusion. In contrast, our sea ice model uses the Material-Point Method (MPM). MPM combines aspects of Lagrangian and Eulerian methods by dividing the domain into a set of unconnected Lagrangian material points, which model advection naturally, and a background grid where the momentum equation is solved. The material points provide a Lagrangian description that is not subject to mesh tangling since the points are unconnected and the background grid provides a convenient way to compute gradients so that the computational work remains linear in the number of material points. In this talk I will give an overview of our sea ice model focusing on our implementation of MPM. CSRI POC: Pavel Bochev, (505) 845-1990 |