Dependence of Radar Backscatter on the Energetics of the Air-Sea Interface
Abstract
The Normalized Radar Cross-Section (NRCS), the fundamental measurement made by radar scatterometers, was obtained as part of the Water-Air Vertical Exchanges 1987 (WAVES87) experiment. The experiment was designed to evaluate the effects of environmental parameters on the NRCS and was performed from a research tower located in Lake Ontario, on which two microwave scatterometers operating at 14.0 and 5.0GHz were installed for six weeks in the autumn of 1987. The novel aspect of this experiment was that the 14.0GHz radar automatically rotated through 300 deg in azimuth angle at six different incidence angles to the water surface, accompanied by simultaneous measurements of wind stress and high resolution directional wave spectra. Therefore, the incidence and azimuthal angle behavior of the NRCS was examined as a function of wind speed, friction velocity, wind direction, wave direction and atmospheric stability. The dependence of the NRCS on wind speed for various incidence angles is similar to previous results. However, the slope exponents of the NRCS vs. 19. 5m wind speed curves at intermediate incidence angles are higher than the corresponding open ocean measurements. Scaling the lake neutral wind speed data by the ratio of lake to ocean drag coefficients reduces the slopes of the curves and suggests the drag coefficient has a sea state dependence.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1989
- Accession Number
- ADA221966
Entities
People
- Marie C. Colton
Organizations
- Naval Postgraduate School