CURRENTS UNDER LAND-FAST ICE IN THE CANADIAN ARCTIC ARCHIPELAGO .2. VERTICAL MIXING

During an acoustic Doppler current profiler (ADCP) study of the veloci ty field under land-fast ice, coincident CTD casts showed three instan ces of pronounced instability in the water column, immediately above a nd below the pycnocline. In this paper we demonstrate that the density inversions are associated with the passage of high frequency linear i nternal waves and finite amplitude waves. Contours of ADCP acoustic re turn intensity display pronounced vertical eddy-like features which ma y indicate overturning. A Richardson number calculation showed that ev en the most highly stratified portion of the pycnocline had sufficient vertical velocity shear to promote dynamic instability. Finally, we c alculate that the vertical nutrient flux, resulting from the high freq uency internal wave field, could supply a significant portion of the i ce-algae nutrient budget.