WIND-DRIVEN DISPERSION IN NEW-JERSEY COASTAL WATERS

Dispersion processes in the near-shore coastal waters 15 km south of t he Hudson-Raritan estuary of New Jersey are investigated using measure ments of velocity and salinity profile at two locations, one 600 m off shore in a 10.7-m-deep water and the other 1,200 m offshore in 12.8-m- deep water. Following the traditional approach, we seek to quantify di spersion coefficient K, representing the various mechanisms responsibl e for alongshore dispersion. The velocity and salinity measurements ar e decomposed into spatial and temporal averages and deviations from th e averages. Using the various correlation terms, contributions to the salt flux in the alongshore direction-such as the mean advection, the residual circulation, and the oscillatory shear flow induced by wind v ariations-are determined. These contributions are then employed in the estimation of the horizontal (along-shore) dispersion coefficient. Th e time variation in the coefficient over the 30-day study period is pr esented, revealing a high degree of variability, with magnitudes rangi ng from 360 to 2,700 m2/s. This variability is attributed to the extre mely variable wind speed and direction observed during the study perio d, with the freshwater discharge of the esturary also playing an impor tant role.