Lagrangian Exploration of the California Undercurrent, 1992–95

Abstract

During the period 1992?95, nineteen isobaric RAFOS floats, placed in the California Undercurrent at intermediate depths (150?600 m) off Monterey and San Francisco, California, reveal a region of varying width of subsurface, poleward flow adjacent to the continental margin. The float trajectories exhibit three patterns: poleward flow in the undercurrent; reversing, but predominately alongshore, flow adjacent to the continental margin;and, farther offshore, anticyclonic motion accompanied by slow westward drift. Flow continuity of the undercurrent exists between Pt. Reyes and at least Cape Mendocino with an average speed dependent on the float depth. Speeds were variable, but common features were acceleration occurring to the south of Pt. Arena and deceleration to the north of Cape Mendocino. An important mechanism for floats, and water, to enter the ocean interior from the undercurrent is through the formation of submesoscale coherent vortices.