Dependence of the normalized radar cross section of water waves on Bragg wavelength-wind speed sensitivity

Measurements of the normalized radar cross section (/spl sigma//spl deg/) made by the YSCAT ultrawideband scatterometer during an extended deployment on the Canada Centre for Inland Waters (CCIW) Research Tower located at Lake Ontario are analyzed and compared with anemometer wind measurements to study the sensitivity of /spl sigma//spl deg/ to the wind speed as a function of the Bragg wavelength. This paper concentrates on upwind and downwind azimuth angles in the wind speed range of 4.5-12 m/s. While YSCAT collected measurements of /spl sigma//spl deg/ at a variety of frequencies and incidence angles, this paper focuses on frequencies of 2.0, 3.05, 5.30, 10.02, and 14.0 GHz and incidence angles within the Bragg regime, 30-50/spl deg/. Adopting a power law model to describe the relationship between /spl sigma//spl deg/ and wind speed, both wind speed exponents and upwind/downwind (u/d) ratios of /spl sigma//spl deg/ are found using least squares linear regression. The analysis of the wind speed exponents and u/d ratios show that shorter Bragg wavelengths (/spl Lambda/<4 cm) are the most sensitive to wind speed and direction. Additionally, vertical polarization (V-pol) /spl sigma//spl deg/ is shown to be more sensitive to wind speed than horizontal polarization (H-pol) /spl sigma/, while the H-pol u/d ratio is larger than the V-pol u/d ratio.