Wintertime mixed layer measurements at Maud Rise, Weddell Sea

• Main Authors: Sirevaag, Anders, McPhee, Miles G., Morison, James H., Shaw, William J., Stanton, Timothy P.
• Format: Article in Journal/Newspaper
• Language: English
• Published: American Geophysical Union 2010
• Subjects: Maud Rise; Weddell; Weddell Sea; Sea ice
• Online Access: https://hdl.handle.net/10945/62326

The article of record as published may be found at http://dx.doi.org/10.1029/2008JC005141. Sea ice plays a crucial role in the exchange of heat between the ocean and the atmosphere, and areas of intense air-sea-ice interaction are important sites for water mass modification. The Weddell Sea is one of these sites where a relatively thin first-year ice cover is constantly being changed by mixing of heat from below and stress exerted from the rapidly changing and intense winds. This study presents mixed layer turbulence measurements obtained during two wintertime drift stations in August 2005 in the eastern Weddell Sea, close to the Maud Rise seamount. Turbulence in the boundary layer is found to be controlled by the drifting ice. Directly measured heat fluxes compare well with previous studies and are well estimated from the mixed layer temperatures and mixing. Heat fluxes are also found to roughly balance the conductive heat flux in the ice; hence, little freezing/melting was observed. The under-ice topography is estimated to be hydraulically very smooth; comparison with a steady 1-D model shows that these estimates are made too close to the ice-ocean interface to be representative for the entire ice floe. The main source and sink of turbulent kinetic energy are shear production and dissipation. Observations indicate that the dynamics of the under-ice boundary layer are influenced by a horizontal variability in mixed layer density and an increasing amount of open leads in the area. The work of M. G. McPhee was supported by the National Science Foundation through grants OPP-0337159 and OPP- 0739371, and the work of J. H. Morison was supported by grant OPP- 0337751. The Naval Postgraduate School is acknowledged for the support for MaudNESS through NSF grant OPP-0338020. This is publication A247 from the Bjerknes Centre for Climate Research. Naval Postgraduate School NSF