Turbulent dissipation and mixing in Prydz Bay

Abstract

In this paper, we present measurements of velocity, temperature, salinity, and turbulence collected in Prydz Bay, Antarctica, during February, 2005. The dissipation rates of turbulent kinetic energy (ɛ) and diapycnal diffusivities (K z ) were estimated along a section in front of the Amery Ice Shelf. The dissipation rates and diapycnal diffusivities were spatially non-uniform, with higher values found in the western half of the section where ɛ reached 10−7 W/kg and K z reached 10−2 m2/s, about two and three orders of magnitude higher than those in the open ocean, respectively. In the western half of the section both the dissipation rates and diffusivities showed a high-low-high vertical structure. This vertical structure may have been determined by internal waves in the upper layer, where the ice shelf draft acts as a possible energy source, and by bottom-generated internal waves in the lower layer, where both tides and geostrophic currents are possible energy sources. The intense diapycnal mixing revealed in our observations could contribute to the production of Antarctic Bottom Water in Prydz Bay.