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Weekly Seminar: Spring 2008

Date: April 25
Time: 11:00 AM
Location: Maryland Hall 110
Speaker: Dr. Balasubramanya Nadiga
Los Alamos National Laboratory
Title:"Eddy Fluxes in Geostrophic Turbulence"

Abstract

Given its importance in parameterizing eddies, the orientation of eddy flux of potential vorticity in geostrophic turbulence is considered. A classical ensemble- or time-average point of view and a second scale-decomposition point of view are considered. In either approach, a net alignment of the eddy flux of potential vorticity with the appropriate mean gradient or the large-scale gradient of potential vorticity is required. This alignment is, however, found to be very weak. A key finding of the study is that in the scale decomposition approach, there is strong correlation between the eddy-flux and a nonlinear combination of resolved gradients. This strong correlation is absent in the classical decomposition. This finding points to a new model to parameterize the effects of eddies in global ocean circulation. Elements of Temporal Eulerian Mean and Temporal Residual Mean theories will be considered.