Numerical Investigation of Inertial and Tidal Variability in Arctic Sea-Ice Deformation

Recent investigations of inertial variability in ice-mixed-layer ocean models by Heil and Hibler (2002) have demonstrated that if artificial water drag is removed from sea ice models, realistic inertial variability in both sea ice drift and deformation may be modeled. Modeled variations were found to be in good agreement with both ice buoy drift and deformation far from shore. These inertial variations were found to increase ice mass up to 20 per cent compared to traditional ice models with passive water drag, and hence can play a significan role in the fresh water budget of the Arctic Ocean. To investigate the additional effects of tidal forcing on the ice as well as feedback between the ice motion and high frequency wave effects in the ocean, a diagnostic free surface ice ocean model is constructed for the Arctic Basin. This model is forced with daily varying wind fields as well as barotropic tidal forcing. The model results are analyzed to demonstrate the significant increase in ice mass that can occur when both these forcings are included in ice ocean models and in stand alone models. As a comparison case, an ice only model with inertial imbedding and tidal forcing is also analyzed to determine to what degree these high frequency effects are dominated by ice mechanics interacting directly with tides and boundary layer inertial motion independent of ocean wave and wind driven vaariability. The results are compared to high frequency buoy drift and deformation and compared to existing ice model simulations.