On the effect of the alongshore pressure gradient on numerical simulations over the Northern California Continental Shelf

Abstract

Chen and Wang's (1990) two‐dimensional shelf circulation model has been extended to include the alongshore (the dimension absent in the model) pressure gradient. The alongshore pressure gradient, calculated independently from a linear coastal‐trapped wave model, is included as an external “forcing”. The extended model has been used to simulate the temperature and velocity fields observed during the Coastal Ocean Dynamics Experiment 2 (CODE 2) in the spring and summer of 1982 on the Northern California Continental Shelf. The results were compared to the CODE 2 observations and to the results of the purely two‐dimensional and coastal trapped wave models. Results using the extended model show some improvement in the cross‐shore and alongshore velocity fluctuations. The differences between the models are explained in terms of the opposition between the wind stress and the pressure gradient in the alongshore direction, which reduces the magnitude of the alongshore velocity. The reduced magnitude of the alongshore flow decreases the alongshore bottom stress which, in turn, reduces the offshore transport in the bottom boundary layer.