Wind‐Driven Dispersion in New Jersey Coastal Waters

Dispersion processes in the near‐shore coastal waters 15 km south of the Hudson‐Raritan estuary of New Jersey are investigated using measurements of velocity and salinity profile at two locations, one 600 m offshore 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 dispersion coefficient $K$, representing the various mechanisms responsible for alongshore dispersion. The velocity and salinity measurements are decomposed into spatial and temporal averages and deviations from the 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 variations—are determined. These contributions are then employed in the estimation of the horizontal (alongshore) dispersion coefficient. The time variation in the coefficient over the 30‐day study period is presented, revealing a high degree of variability, with magnitudes ranging from 360 to 2,700 m²/s. This variability is attributed to the extremely variable wind speed and direction observed during the study period, with the freshwater discharge of the esturary also playing an important role.