The low-frequency transport in the Santa Barbara Channel: description and forcing

Abstract

Current meter, wind and adjusted sea level (ASL) data from January to July 1984 are used to (a) isolate the currents inside the channel that are associated with low-frequency (6–18 day band) transport fluctuations which dominate the record of the eastern mouth transport and (b) find the forcing mechanism(s) and its(their) dynamical role(s) in the low-frequency transport. The dominant mode of the currents is highly coherent with the eastern mouth transport in the 6–18 day band. About 62% of the total variance of the eastern mouth transport can be hindcast by both wind stress and remote adjusted sea level (ASL). The comparison of the amplitudes, and phases of the regression coefficients of a multiple regression analysis, to the amplitudes and phases expected from momentum conservation suggests that both the alongshore remote pressure gradient and the local wind stress forcing are balanced at the eastern mouth of the channel by the local acceleration of the transport there. The ASL data analysis suggests evidence of low mode coastally trapped wave propagation from San Quintin in Mexico to Port San Luis in central California. A quasi-linear phase vs longshore distance implies a propagation speed of about 70 km day −1 (period of 13.6 days), which compares well with the theoretical value of 75 km day −1 (period of 13.3 days) for the Southern California Bight.