Estimating Mixing Rates and Turbulence from Glider-based Microstructure Measurements in the Beaufort Sea

Understanding mixing rates and mechanisms in the Arctic Ocean allows us to estimate vertical heat fluxes through the watercolumn which have the potential to significantly impact heat budgets as well as ocean-sea ice and ocean-atmosphere interactions. We present new observations consisting of 400+ quasi-vertical microstructure profiles of shear and temperature variance alongside profiles of finescale temperature and salinity in the Amundsen Gulf region of the Canadian Arctic. We use these to characterize the variability of turbulent mixing rates in both space and time, and to begin identifying the dominant physical processes responsible for mixing in this region. The measurements were collected over two weeks by an autonomous glider in August 2015, and they represent one of the most dense microstructure sampling schemes in the Arctic to date. Profiles encompass the most prominent features of the Arctic water column, including the warm Atlantic water layer at depths below 250 m, the halocline between the Pacific and Atlantic water layers, and the surface mixed layer which exhibits a strongly stratified base. From the microstructure measurements, we calculate ε and χ, the dissipation rates of turbulent kinetic energy and thermal variance, and using these, estimate the distribution of mixing rates (i.e. the turbulent diffusivity). We relate this distribution to the background environment, the presence of topographic features, and the proximity to the shelf-slope in order to gain insight into the dominant mixing mechanisms.