Modeling studies of the coastal circulation off northern California

By implementing a series of mass-conserving nested high-resolution models down to approximately 1 km resolution that have realistic bathymetry, coastline, wind forcing and river run-off, the winter 1996--1997 shelf flow near Cape Mendocino, California, is simulated and compared with available observations from the Strata Formation on Margins (STRATAFORM) marine geology program. The model simulations are used to statistically characterize winter circulation, and to associate shelf flow response with specific forcing mechanisms. Major forcing mechanisms include highly complicated bathymetry in the vicinity of the headland of Cape Mendocino, and winds that are controlled by propagating storm systems. These storms have high wind speeds (up to 20 m s--1 ) and drop significant precipitation that causes flooding of the rivers that drain the coastal mountain range.; Nesting techniques developed in meteorology are first tested in idealized scenarios that extract crucial dynamics of the coastal ocean. Realistic high-resolution nested models are then embedded in the 9-km resolution Naval Research Laboratory Pacific West Coast (NRL PWC) regional model of the North Pacific Ocean. The first nested model has 3 km resolution and extends from 38.6°N to 43°N, and offshore to 127.1°W. This model displays strong alongshore variability with more energetic flow located north of Cape Mendocino. This alongshore asymmetry is enhanced by river run-off that bathes the shelf north of Cape Mendocino during winter storms. An anticyclonic eddy north of Cape Mendocino is a generic circulation feature that occurs as poleward winds weaken and change direction during storm passage.; The 1-km resolution nested model, extending from 39.5°N to 42°N, and west to 125.9°W, is used to simulate the 80-year January 1997 Eel River flood event. The simulation illuminates the interaction of the Eel River plume with the background shelf flow. The plume responds to wind forcing in a manner consistent with Ekman dynamics. Furthermore, the plume becomes entwined in the mesoscale eddy whose formation and characteristics were documented in the 3-km simulation.