Eddy Fluxes and Second-Order Moment Balances for Nonhomogeneous Quasigeostrophic Turbulence in Wind-Driven Zonal Flows*

Abstract

Abstract The balances of momentum and second-order moments (potential enstrophy, energies, and potential vorticity flux) of wind-driven zonal flow, using a suite of numerical eddy resolving experiments in a two-layer channel, governed by quasigeostrophic dynamics, are investigated. The flow regime in these experiments does not satisfy the usual scaling of quasigeostrophic large-scale dynamics: relative vorticity is a significant contribution to the quasigeostrophic potential vorticity (QPV) in the deep layer and the lateral Reynolds stress divergence is comparable to the interfacial form stress in the top layer. The balances of second-order moments confirm that the eddy-induced fluxes of QPV and layer thickness are downgradient but significant contributions of triple moments occur. Existing parameterizations and scaling laws of the eddy fluxes of QPV and layer thickness are tested against data from the numerical experiments and it is shown that the usual downgradient forms of parameterization with diffusi...