Diurnal sea breeze effects on inner-shelf cross-shore exchange

Abstract: Cross-shore exchange by strong (cross-shore wind stress, τsx >0.05Pa) diurnal (7–25h) sea breeze events are investigated using two years of continuous wind, wave, and ocean velocity profiles in 13m water depth on the inner-shelf in Marina, Monterey bay, California. The diurnal surface wind stress, waves, and currents have spectral peaks at 1, 2, and 3cpd and the diurnal variability represents about 50% of the total variability. During sea breeze relaxation (−0.05<τsx <0.05Pa), a background wave-driven inner-shelf Eulerian undertow profile exists, which is equal and opposite to the Lagrangian Stokes drift profile, resulting in a net zero Lagrangian transport at depth. In the presence of a sea breeze (τsx >0.05Pa), a uniform offshore profile develops that is different from the background undertow profile allowing cross-shore Lagrangian transport to develop, while including Lagrangian Stokes drift. The diurnal cross-shore current response is similar to subtidal (>25h) cross-shore current response, as found by . The seasonality of waves and winds modify the diurnal sea breeze impact. It is suggested that material is not transported cross-shore except during sea breeze events owing to near zero transport during relaxation periods. During sea breeze events, cross-shore exchange of material appears to occur onshore near the surface and offshore near the sea bed. Since sea breeze events last for a few hours, the long-term cross-shore transport is incremental each day. [Copyright &y& Elsevier]