FY 1982

Near-shore currents measured in ridge-and-swale topography off Long Island, New York

Lavelle, J.W., and D.J.P. Swift

J. Geophys. Res., 87(C6), 4190–4194, doi: 10.1029/JC087iC06p04190 (1982)

Eighteen near-shore current records within an area 11 km on the Long Island inner shelf have been examined for indication of small-scale topographic influence. In the frictionally influenced near-shore water column, currents over the 39-day records are generally oriented slightly clockwise of the longshore direction toward the principal axis of the local ridge-and-swale topography. This orientation angle is largest and closest to the local topographic axis when semidiurnal tidal currents dominate other flows, a result which may suggest that tidal currents play a role in molding the local topography. Viscous tidal current theory for a constant depth surface describes the observed dependence of the semidiurnal (M) tidal current ellipticity and ellipse orientation on depth. The inferred vertical eddy viscosity coefficient ranges from 5 to 35 cm/s.