With the rapid decline of Arctic sea ice,the freshwater produced by melting of summer sea ice makes the depth of the halocline under ice become shallower.This has an impact on the drift of sea ice because internal waves may be generated at the interface of the halocline by disturbance from the draft of an ice floe or ridge keel.A laboratory experimental study was carried out to investigate the interactions between an ice ridge and stratified fluid using the method of Particle Image Velocimetry(PIV).The drift velocity of an ice ridge(U) and the draft of the ridge keel(D) were altered in different experimental cases,and the velocity field in the stratified fluid was then measured by PIV.The results reveal that an obvious vortex exists in the wake field of the ridge keel,and the center of the vortex moves away from the ice ridge with increasing D.Internal waves at the interface of the stratified fluid were observed during the drift of the ice ridge,and the wave height shows a positive correlation with U and D.This study demonstrates that ice ridges could introduce internal waves at the interface of a stratified fluid and thus affect the oceanic drag coefficient and ice drift.It supports improved parameterization of the ice drag coefficients.
