On Forecasting Mesoscale Ice Dynamics and Build-Up

Due to the nonlinear nature of the ice interaction, sea-ice build-up against coasts and structures is a complex process. This build-up signifycantly affects mesoscale (10 to 100 km) ice motions over typical forecast time scales of several days. To examine the ramifications of assuming a non-linear ice interaction in ice forecast models, we have carried out a series of idealized simulations employing a viscous plastic sea-ice rheology (Hibler 1979). These simulations employ constant wind fields at a grid resolution of 18.5 km and allow the ice to build up and strengthen. With the plastic ice interaction the ice build-up is found to take place by means of a ridging front. Depending on the nature of the strength-thickness coupling, this build-up is accompanied by kinematic wave propagation effects. The nonlinear interaction can also result in fluctuating velocities in certain locations, even though the forcing is fixed. The build-up results are found to be consistent with the analytic solution of a one-dimensional rigid plastic model.