Wind forced oceanic responses near ice edges revisited

Abstract

Abstract The wind forced response of a flat bottomed, stratified, hydrostatic ocean on the f-plane near an ice edge is studied by means of an analytical theory. The properties of the ice are implicitly taken into account as a medium to communicate the wind stress to the water below the ice cover. The consistency of the ice (grease, floes of varying size, or pack ice etc.) as well as the stability of the atmospheric boundary layer causes variations of the effective drag coefficient. Various types of across-ice-edge profiles of the wind stress were recently discussed by Guest et al., which can be modelled by a piecewise linear profile with a maximum close to, but iceward of the edge. We consider fixed and moving ice edges with piecewise constant and piecewise linear cross-edge wind stress profiles. The response patterns are characterized by the along-edge jets as well as up- and downwelling near the ice edge. The detailed structures depend crucially on the wind stress profile and the movement of the ice edge. The spatial scales of the wind driven oceanic responses near the ice edge are set by the baroclinic Rossby radius, R 1 the distance the edge has travelled, and by the structure of the wind stress profile. The time scales are basically determined by the duration of the forcing. Comparisons with observations show that a relative simple analytical model is able to describe qualitatively the observed features.