21.01.2013: FB1-Seminar

11:00 h, Hörsaal (West)


Abstract:

In the subpolar North Atlantic, the mixing induced transformation of water masses maintains the ocean stratification and supports the Meridional Overturning Circulation.

During the years 2003-2011, nine large-scale hydrographic surveys were carried out with combined CTD/LADCP measurements in this area; more than 700 profiles of current velocity, temperature and salinity were obtained during these cruises. Under the assumption of steady state, distribution of turbulent mixing at depths below the pycnocline is inferred in the way of diapycnal diffusivity Kρ, and its possible dependences on environmental parameters are analyzed.

It shows strong local variability: Kρ is generally close to the background value (O(10^-5) m²s^-1) in the interior of the Labrador Sea; somehow elevated at mid-depth in the open ocean; high values are found over rough seafloor in the abyss and in the boundary areas. Hot spots exceeding 10^-3m²s^-1 appear in the western boundary and south to the Greenland. Mixing in the subpolar region of North Atlantic is enhanced by the rapidly changed topography, and tends to be affected by the deep current and eddies.