Mixing Processes in the Dotson Ice Shelf Outflow

The Dotson Ice Shelf (DIS) shows high rates of basal melting in recent decades. Relatively warm ocean currents access the sub-ice shelf cavity and interact with the base of the ice shelf providing heat for its melting. The water mass transformation associated with the mixture of warm water and meltwater creates buoyant plumes that shallow as they flow out from the cavity. Here, we show that high turbulent kinetic energy (TKE) dissipation rates (up to order 10⁻⁷ W kg⁻¹) and diapycnal eddy diffusivities (up to order 10⁻² m² s⁻¹) are associated with the outflow current from DIS. Four high-resolution Vertical Microstructure Profile (VMP) and ship-based Acoustic Doppler Current Profiler (SADCP) sections were conducted in January and February 2022 at the western side of DIS spanning the outflow as it hugs the steep topographic slope. Near-bed TKE dissipations rates are elevated by up to 3 orders of magnitude and elevated mixing rates are also observed mid-water column around the edges of the outflow. These elevated TKE are associated with friction near the bed and current shear at the outflow boundary. In this presentation, we explore the consequences for dissipation of physical and biogeochemical properties.