Microwave Scattering from Internal Wave Modulated Surface Waves: A Shipboard Real Aperture Coherent Radar Study in JOWIP (The Georgia Strait Experiment)

摘要

A shipboard coherent dual-polarized focused radar operating at 9.23 GHz and an optical device which detects the occurrence of specular reflection at the radar incidence angle have been used to investigate mechanisms governing radar backscatter from surface water waves as part of JOWIP (The Georgia Strait Experiment). The relative contributions of Bragg and specular backscatter mechanisms have been identified using the output of the optical specular detector and the radar backscatter polarization ratios. Analysis of the radar data together with data from the DREP laser wave slope gauge has been used to further identify the mechanisms governing radar backscatter and modulations of radar backscatter from surface water waves. It is found that specular reflection is very significant at 20 deg. incidence angle and not negligible at 40 deg. It is found that when specular contributions are absent the relationship between the surface wave slope and the radar backscatter is well-described by Bragg theory. Specular contributions, when they occur, appear as large spikes on top of the Brag Bragg theory. Specular contributions, when they occur, appear as large spikes on top of the Bragg return. (RRH)