Modeling multi-scale interactions on the inner shelf: the effect of alongshore variability
Sutara H Suanda, Scripps Institution of Oceanography, La Jolla, CA, United States, Nirnimesh Kumar, Scripps Institution of Oceanography, Integrative Oceanography Division, La Jolla, CA, United States, Arthur J Miller, Scripps Institution of Oceanography, UC San Diego, La Jolla, CA, United States, Emanuele Di Lorenzo, Georgia Institute of Technology Main Campus, Program in Ocean Science & Engineering, Atlanta, GA, United States, Kevin A Haas, Georgia Tech Savannah, Civil Environmental Engineering, Atlanta, GA, United States, Donghua Cai, Georgia Institute of Technology, Civil Engineering, Atlanta, GA, United States, Falk Feddersen, University of California San Diego, La Jolla, CA, United States and Christopher A Edwards, University of California Santa Cruz, Santa Cruz, CA, United States
Abstract:
Circulation on the inner-shelf (5 – 30 m water depth) is subject to the combined forcing of submesoscale, coastal wind-driven, tide-topography, Stokes drift transport, and surfzone processes. As part of a pilot study for the ONR Inner Shelf DRI, the COAWST (coupled ROMS-SWAN) model with five levels of successive one-way nesting are used to resolve and study the interaction between large and small scale processes on a realistic inner shelf near headland topography north of Pt. Conception, CA.
At subtidal frequencies, inner shelf variability is dominated by alongshore wind forcing. The model reproduces the alongshore varying response of currents and temperature to coastal upwelling in the presence of a headland and compares well to available observations. During wind reversals, the northward excursion of warm Southern California Bight water provides remote forcing to this inner shelf. While local barotropic tidal effects (headland eddy generation) are mostly confined to within a few kilometers along- and offshore of the headland, shoreward-propagating baroclinic tides increase tidal variability across the entire inner shelf. Furthermore, alongshore variations associated with headland-wind interactions disrupt the propagation of internal tides and create alongshore gradients in cross-isobath internal tide energy flux. The addition of surfzone processes increases inner-shelf velocity variance and creates small-scale alongshore variability not associated with headland topography.
