ON THE RESPONSE OF THE EQUILIBRIUM THICKNESS DISTRIBUTION OF SEA ICE TO ICE EXPORT, MECHANICAL DEFORMATION, AND THERMAL FORCING WITH APPLICATION TO THE ARCTIC-OCEAN

The areal ice distribution in a pack ice field is described using a number of classes, characterized by different ice thicknesses. Each class may have a snow layer on top and evolves according to the thermodynamic forcing (same for all classes) and is followed through time. Mechanical forcing leads to ice export and deformation. The ice export is quantified by the parameter e describing the areal export of ice per unit of time. The deformation is quantified by the parameter r describing the area of open water generated by deformation per unit of time. The fraction of summer heat absorbed in leads and utilized for ice melting is quantified by the parameter g(op). The model is applied to the Arctic Ocean. It is run to a steady state for different combinations of e, r, and g(op), and the response of the thickness distribution to these parameters may thereby be quantified. It is shown that the ice generally gets thinner for increasing export. The response to deformation is dependent on g(op) such that the mean thickness increases with r for small g(op) (i.e.. no effect or just a small melting effect of the heat absorbed in leads) but decreases with r for large g(op). The overall effect of g(op) is that the mean thickness decreases with increasing g(op). For g(op), close to l and moderate values of e and r the ice sheet melts completely in the summer.