Current and Density Observations of Packets of Nonlinear Internal Waves on the Outer New Jersey Shelf

Closely spaced observations of nonlinear internal waves (NLIWs) were made on the outer continental shell off New Jersey in June 2009. Nearly full water column measurements of current velocity were made with four acoustic Doppler current protilers (ADCP's) that were moored about 5 km apart on the bottom along a line approximately normal to the bathymetry between Water depths of 67 and 92 in. Density profiles were obtained from two vertical strings or temperature and conductivity sensors that were deployed near each of the interior A DCP moorings. In addition, a towed Scan Fish provided profiles and fixed-level records of temperature and salinity through several NLIW packets near the moorings. Several case studies were selected to describe the propagation of the NLIWs. One to three solitary waves of depression were observed in live selected packets. There were also occurrences of multiple-phase dispersive wave packets. The average propagation speed corrected for advection of the observed waves was 0.51 +/- 0.09 m s(-1) The waves were directed primarily shoreward (northwestward) along the mooring line with average wavelengths and periods of about 300 m and 10 min. respectively. Wave amplitudes and energies decreased with decreasing water depth. The observed wave parameters can be locally described by a two-layer Korteweg-de Vries (KdV) model, except for the decreasing amplitudes, which may be due to shear-induced dissipation and/or bottom drag. The various complementary observations utilized in this study present a unique description of NLIWs.