Measurement of microwave backscattering signatures of the ocean surface using <i>X</i> band and <i>K_a</i> band airborne scatterometers

Abstract

An airborne microwave scatterometer‐radiometer system operated in X band and K a band was applied to the observations of microwave backscattering signatures of the ocean. The normalized radar cross sections σ 0 were measured as combined functions of microwave frequency (10.00 GHz and 34.43 GHz), polarization (HH and VV), incident angle (0°–70°), azimuth angle (0°–360°), and wind speed (3.2–17.2 m/s). The azimuth anisotropic signatures for K a band are confirmed to be similar to those for X band, and the wind speed dependences are analyzed for each azimuth angle, polarization, and incident angle. For each parameter the behaviors of σ 0 for microwave frequencies is shown as compared with the results obtained by other experiments and theories. The effective reflection coefficient, the mean square surface slope, and the two‐dimensional wave number spectrum of the short surface waves are estimated from the microwave scattering signatures.