Southern Ocean Mixing Workshop November 14-15, 2005   E-mail     Print     PDF

	Enlarge Image Schematic of the Southern Ocean Meridional Overturning Circulation (looking to the southwest with Antarctica on the left) supported by topography in the abyss (smooth arrows), eddy- driven fluxes and mixing-induced secondary circulations at mid-depth ("wiggly arrows") and Ekman dynamics at the surface (Adapted from Speer, et al. 2000)

Mixing in the Southern Ocean appears to play a critical role in the global meridional overturning circulation (MOC). In the Southern Ocean, deep and intermediate waters are hypothesized to upwell along isopycnals. At the surface, these water masses are advected meridionally and transformed to create bottom water and SubAntarctic Mode Water, which in turn downwell along isopycnals. Since the primary current of the Southern Ocean, the ACC, is zonally connected, no mean geostrophic current can carry water meridionally along these mid-depth and upper-ocean isopycnal surfaces. The dominant mechanism for the meridional transport of mass, heat, and potential vorticity above the topography and below the wind driven Ekman layer at the latitude band of Drake Passage is thought to be quasi-geostrophic, mesoscale eddy motions. Diapycnal mixing processes might also support residual ageostrophic circulations that contribute to the Southern Ocean MOC, but also appear able to “short-circuit” the meridional fluxes associated with the eddy motions.  Furthermore, turbulent dissipation within the ACC may be a significant sink for the energy put into the ocean by winds acting on the Southern Ocean.

A group of physical oceanographers in the U.S. and U.K. have identified mixing processes in the Southern Ocean as a critical climate research question.  An experiment has been conceived to investigate Isopycnal and Diapycnal Mixing processes in the Southern Ocean (DIMES).  In order to focus the science questions and coordinate U.S. and U.K. field program ideas and proposal plans, a workshop at the Woods Hole Oceanographic Institution will be held on November 14-15 in Carriage House.  A detailed agenda will be forthcoming.  Students and other scientists in the WHOI community interested in mixing processes in the Southern Ocean are invited to attend the workshop.  As part of the workshop, the weekly Physical Oceanography seminar (Nov 15, 1500, 507 Clark Laboratory) will be given by Dr. Alberto C. Naveira Garabato, School of Ocean and Earth Science, National Oceaography Centre, Southampton, UK, entitled "Southern Ocean mixing:  A paradigm crossroads."