Circulation and energetics of a model of the California current system

Abstract

Uses data from an eight layer FNOC wind driven, eddy resolving, limited area, quasi-geostrophic numerical model to study the dynamics of the California Current System. Study of the general circulation field reveals the weakening of the Davidson Current and intensification of the California Current along the Baja California coast, and four regimes can be identified on the basis of the potential vorticity field (inertial, intermediate, beta and bottom topographic). Presents detailed stability and energetics analyses. In the two or three uppermost layers total circulation is generally controlled by the mean circulation and below those layers by the eddy fluxes. Shows that, with the exception of the area of the California Current main flow, production of eddy kinetic energy is due to local 'linear' baroclinic instability rather than to nonlinear processes. Enstrophy analysis of the turbulent activity in the forced layer north of about 28 degrees N indicates that strong turbulence is confined to the top layer. The wind, through the Ekman pumping mechanism appears to be responsible for the generation of quasi- linear first baroclinic mode annual Rossby waves between 25 and 33 degrees north. (C.J.U.)