Polarization and look-direction dependencies observed in radar imagery of the Chesapeake Bay Outflow Plume front

In May 1997 and May 1999, the Remote Sensing Division of the Naval Research Laboratory conducted phases Two and Five of the Chesapeake Bay Outflow Plume Experiment (COPE2 and COPE5, respectively). In both experiments, an airborne, X-band, real-aperture radar was used to image the outflow plume front that forms in the mouth of the Chesapeake Bay. On an interleaved, pulse-to-pulse basis, both horizontally and vertically polarized imagery was collected. In COPE5, backscatter intensity were observed polarization when the look direction and grazing angle were varied, with the largest across-the-front backscatter contrast occurring at an 80 degree incidence angle when a landward look direction was used. The strongest backscatter was observed on the continental shelf side, regardless of look direction. In COPE2, large contrasts in backscatter intensity were also observed for horizontal polarization, but the look dependency was reversed: larger contrasts were observed when a seaward look direction was used, and the strongest backscatter was observed on the plume-side of the front. In this paper, these observations will be quantified, and an explanation for this interesting behavior will be given that involves the interaction of wind waves and opposing currents