Author(s): Peng Lu; Wen Tie; Bo Li; Yan Wu; Zhijun Li
Keywords: No Keywords
Abstract: With the enhanced summer melting of Arctic sea ice, a strong halocline was frequently observed at a shallower water depth (10-20 m) than in past (50 m) especially in the marginal ice zone of the Arctic Ocean. The shallow halocline poses an important impact on the drift of sea ice because ice draft and ridge keel would induce internal waves on the interface of stratified fluid. To include the effect of internal wave on the oceanic drag force into the parameterization of sea ice drag coefficient, a series of laboratory experiments was conducted to study the drag force on ice ridge keel in stratified flows, and combinations of different drift velocity (U) and draft (D) of ice ridge were considered in the tests. The results revealed that comparing with the monotonically increasing drag force with drift velocity in uniform flow, the drag force in stratified flow (F) shows a non-monotonic variation along with the drift velocity. With increasing velocity, a peak of F is firstly achieved and then drops to a valley, and finally increases gradually as that in the uniform flow. The drag coefficient (C) on ridge keel was also calculated based on the drag force measured in the stratified flow. Its value shows a peak as U is nearly half of the phase velocity (U) of the internal waves on the interface of stratified water, and becomes constant as U> > U.