Turbulence north of Svalbard in summer 2018: mixed layer evolution and Atlantic Water layer dynamics
In summer 2018, turbulence structure in the Atlantic Water boundary current was measured north of Svalbard in two different periods (July and September), within the framework of the Nansen Legacy project. Turbulence profiles were collected using a Vertical Microstructure Profiler (Rockland Scientific) in both cruises (total of 240 profiles) and a Microrider (Rockland Scientific) mounted on a Slocum glider (4 days of data, 54 dives and 108 profiles) in September.
We investigated changes in the mixed layer through the summer and the sources of vertical mixing in the water column. In the mixed layer, depth-integrated turbulent dissipation rate is about 10-4 W m-2. Variations in the turbulent heat, salinity and buoyancy fluxes are strong, and hypothesized to be affected by the evolution of the surface meltwater layer through summer. When integrated over the Atlantic Water layer, the turbulent dissipation rate is about 3.10-3 W m-2. Whilst the wind work exerted in the mixed layer accounts for most of the variability in the mixed layer, tidal forcing plays an important role in setting the dissipation rates deeper in the water column.