A Time-Dependent Model of a Coastal Polynya

Abstract

An idealized model is used here to examine the temporal behavior of a coastal polynya driven by an offshore wind. The model has incorporated the important effect of a finite surface dift by which the frazil ice formed in the open ocean is advected downwind and collected at the ice edge. It is found that a finite surface drift, on the one hand, reduces the ?inertia? of the ice edge, thus prompting a greater response for a given flux inbalance, but on the other, delays and smooths out the forcing effect at the ice edge. The resulting polynya behavior is examined in response both to a finite step change and small perturbations in the atmospheric forcing. The model results suggest, among other things, that the ice edge is in approximate equilibrium with synoptic and longer-period atmospheric variations, but is not responsive to higher-frequency atmospheric fluctuations with periods short compared with the transit time of a water parcel through the polynya.