VARIABILITY AND CLIMATE SENSITIVITY OF LANDFAST ARCTIC SEA-ICE

A one-dimensional thermodynamic sea ice model is used to perform multi year simulations of land-fast sea ice and its snow cover. The model is applied to two locations in the Canadian high Arctic: Resolute and Al ert, Northwest Territories. The sites are chosen because meteorologica l observations and ice and snow depth measurements spanning the period 1955-1990 are available. Bulk formulae are used to convert standard m eteorological observations into surface fluxes, snowfall is specified from observed annual accumulation, and a crude oceanic mixed layer is included to allow heat storage during ice-free summer months. The mode l is successful at reproducing seasonal and interannual variability in maximum ice thickness, snow depth, freeze-up, and breakup dates. Sens itivity studies demonstrate the relative importance of variables such as air temperature and snowfall rate on interannual variability of max imum ice thickness and the duration of the ice-free season. Multiple e quilibria, corresponding to thin, seasonal ice and thick, perennial ic e, are shown to exist in the model. Climate sensitivity experiments il lustrate the potential effects of changes in air temperature and snowf all on ice thickness and open water duration in the Canadian Archipela go.