UPWIND-DOWNWIND-CROSSWIND SEA-CLUTTER MEASUREMENTS.
Abstract
Radar returns were collected nearly simultaneously on four frequencies-428 MHz, 1228 MHz, 4455 MHz, and 8910 MHz-for both linear and cross polarizations. In the course of these measurements, sea clutter was recorded in the upwind, downwind, and crosswind directions. The ratios of the upwind-to-downwind and upwind-to-crosswind returns were investigated as functions of the incident angle, the polarization, the radar wavelength, and the gross surface parameters of wind velocity and wave height. The upwind/downwind ratio is shown to decrease with increasing angle and surface roughness. Horizontal polarization is more sensitive to wind direction than vertical polarization. The short wavelengths are more sensitive to wind direction than the long wavelengths. The upwind/crosswind ratio remains significant as the short wavelengths for the roughest sea encountered at Puerto Rico. The results provide estimates of the upwind-downwind-crosswind relations as functions of the above parameters over an angular region of 4 to 90 degrees (vertical incidence) and from calm sea conditions to moderately rough conditions characterized by 5 - to 7-ft wave heights and 10 - to 20-knot winds. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 14, 1969
- Accession Number
- AD0687403
Entities
People
- James R. Duncan
- John C. Daley
- John T. Ransone Jr.
- Joseph A. Burkett
Organizations
- United States Naval Research Laboratory