An air-sea feedback mechanism for quasi-geostrophic water movement near a fast shelf ice edge with a small curvature

Abstract

An air-sea coupled model developed in this paper is intended to depict the generation of unstable coastal water waves near a fast shelf-ice edge with small curvature. Without any external forcing of the system, the unstable models are excited by the air-sea feedback mechanism. Thermally forced surface winds, generated by surface temperature gradient that is related to the vertical displacement by a surface temperature gradient that is related to the vertical displacement of the pycnocline, in turn produce a surface water current that further changes the vertical displacement of the pycnocline. The model consists of two elements: thermally forced surface air flow and mechanically driven coast water waves (Clarke). The two components are linked through the surface temperature gradient and surface wind stress. The coupled air-sea model is solved as an eigenvalue problem. It is found that the iceward convex ice-age, relatively thin ice, and small upper-layer water depth favor the generation of very unstable models. The influence of the coupling on the wave velocity is also discussed.