DIRECTIONAL OCEAN WAVE MEASUREMENTS IN A COASTAL SETTING USING A FOCUSED ARRAY IMAGING RADAR

A unique focused array imaging Doppler radar was used to measure direc tional spectra of ocean surface waves in a nearshore experiment perfor med on the North Carolina Outer Banks. Radar images of the ocean surfa ce's Doppler velocity were used to generate two dimensional spectra of the radial component of the ocean surface velocity field. These are c ompared to simultaneous in-situ measurements made by a nearby array of submerged pressure sensors. Analysis of the resulting two-dimensional spectra include comparisons of dominant wave lengths, wave directions , and wave energy accounting for relative differences in water depth a t the measurement locations. Limited estimates of the two-dimensional surface displacement spectrum are derived from the radar data. The rad ar measurements are analogous to those of interferometric synthetic ap erture radars (INSAR), and the equivalent INSAR parameters are shown. The agreement between the remote and in-situ measurements suggests tha t an imaging Doppler radar is effective for these wave measurements at near grazing incidence angles.