Variability and climate sensitivity of landfast Arctic sea ice

A one-dimensional thermodynamic sea ice model is used to perform multiyear simulations of land-fast sea ice and its snow cover. The model is applied to two locations in the Canadian high Arctic: Resolute and Alert, Northwest Territories. The sites are chosen because meteorological observations and ice and snow depth measurements spanning the period 1955-1990 are available. Bulk formulae are used to convert standard meteorological 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 model is successful at reproducing seasonal and interannual variability in maximum ice thickness, snow depth, freeze-up, and breakup dates. Sensitivity studies demonstrate the relative importance of variables such as air temperature and snowfall rate on interannual variability of maximum ice thickness and the duration of the ice-free season. Multiple equilibria, corresponding to thin, seasonal ice and thick, perennial ice, are shown to exist in the model. Climate sensitivity experiments illustrate the potential effects of changes in air temperature and snowfall on ice thickness and open water duration in the Canadian Archipelago.