X-band microwave backscattering from ocean waves
- TRW Space and Electronics Group, Redondo Beach, CA (United States); and others
Backscattering experiments at microwave frequencies were conducted off the west coast of Scotland in the summer of 1991. Using a dual-polarization, 8-frequency X-band coherent scatterometer mounted on the bow of a boat, we measured time-resolved backscattering from ocean waves at a range of grazing angles from 10{degrees} to 70{degrees}. From the grazing-angle-dependent signals and their Doppler spectra, we differentiate Bragg scattering from non-Bragg scattering and resolve ``peak separation`` between the vertical and horizontal polarizations. We observe instances of ``super`` events, i.e., instances when the horizontal polarization return power equals or exceeds the vertical polarization power. We find that ``super`` events occur not only at low grazing angles but at any grazing angle for against-wind viewing directions. Statistics for such occurrences as a function of grazing angle are obtained. We study the coherence properties of scatterers and find strong evidence that at low grazing angles, lifetime-dominated, non-Bragg scattering contributes noticeably to returns of both polarizations, but is dominant in providing returns for the horizontal polarization. We examine ``spiking`` events and find that they can be related to, but need not be limited to, breaking wave events. By comparing the data of against-wind runs with cross-wind and circle runs, we obtain wind-direction dependence of Doppler spectra which further assists in the identification of scattering mechanisms.
- Research Organization:
- Lawrence Livermore National Lab., CA (United States); TRW Space and Electronics Group, Redondo Beach, CA (United States)
- Sponsoring Organization:
- Department of Defense, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 10175850
- Report Number(s):
- UCRL-CR-117680; CONF-940814-3; ON: DE94016719
- Resource Relation:
- Conference: IGARSS `94: international geoscience and remote sensing symposium,Pasadena, CA (United States),8-12 Aug 1994; Other Information: PBD: 4 Jan 1994
- Country of Publication:
- United States
- Language:
- English
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