Modeling studies of the effects of wind forcing and thermohaline gradients on the California Current System

Abstract

This process-oriented study uses a high-resolution, multi-level, primitive equation model to study the combined effects of wind forcing and thermohaline gradients on the ocean circulation of the California Current System (CCS). The ocean circulation is generated by the model using a combination of climatological wind stress forcing and thermohaline gradients. In the first experiment, the effects of thermohaline gradients alone are evaluated; in the second experiment, previously conducted, the effects of wind forcing are isolated; while in the third experiment, the combined effects of wind forcing and thermohaline gradients are investigated. The results from the combined experiment show that even though the effects of wind forcing dominate the CCS, the additional effects of thermohaline gradients results in the following: the seasonal development of a poleward surface current and an equatorward undercurrent in the poleward end of the model region; an onshore geostrophic component, which results in a temperature front and stronger surface and subsurface currents between Cape Mendocino and Point Arena; and a region of maximum eddy kinetic energy inshore of ∼125W between Cape Mendocino and Point Arena, associated with the temperature front. These model simulations are qualitatively similar to recent hydrographic, altimetric, drifter, and moored observations of the CCS.