UC San Diego

This main objective of this study is to identify and estimate the contribution of various forcing mechanisms that drive cross-shore exchange in the inner shelf, off the coast of central Point Loma. Analysis of the structure of velocity profile time series recorded by a bottom- mounted ADCP indicates that internal tides are the dominant mechanism contributing to cross-shore exchange on the inner-shelf. Exchange is predominantly manifested via a two-layered exchange mode. Much of the variability explained by this mode is associated with the M₂ internal tide. The total M₂ energy is found to be stronger beneath the thermocline for most of the year. The vertical asymmetry of the M₂ is accounted for by the phase relationship between the barotropic and baroclinic M₂ tide. Seasonal shifts in the depth of the thermocline determine the vertical extent of the baroclinic M₂ in the lower layer. The exchange flux driven by the M₂ accounts for approximately 35% of the net cross-shore exchange flux. Variability in diurnal processes is relatively weaker. It is mostly accounted for by semi-diurnal and diurnal internal tides in the summer