Orszag applied renormalization group (RNG) methods to the analysis of hydrodynamic turbulence and deduced a closure second order scheme to calculate the eddy viscosity and eddy diffusivity produced by subgrid eddies. One of the assumptions of the method is that turbulence is isotropic. Two major facts that produce anisotropy in geophysical flows are rotation and stratification. Here he proposes to study the effect of rotation and stratification on the turbulence schemes and apply the results to specific oceanographic problems, including models of the thermocline in the equatorial Pacific.
