Tidal inlet circulation: observations, model skill and momentum balances
A combined observational and modeling study of circulation at Beaufort Inlet, North Carolina is underway to elucidate circulation patterns and momentum balances at shallow barrier island inlets. The observational data include fourteen shipboard ADCP cruises, each over a complete semi-diurnal tidal cycle. A high resolution (<50 meter grid spacing) depth-integrated nonlinear barotropic model is used to simulate the circulation. With simple model forcing, preliminary comparisons with semi-diurnal tidal ellipse data are quite favorable. The contribution of each term in the momentum equations to the overall momentum balance is determined from model elevation and velocity fields. Results show that at maximum ebb the streamwise momentum balance is dominated by advective acceleration, pressure gradient, and bottom friction. In the cross-stream direction the momentum balance is dominated by the centrifugal acceleration, pressure gradient, and (to a lesser degree) Coriolis. Momentum balances were highly localized, often with sub-kilometer length scales.
