A note on Doppler processing of coherent radar backscatter from the water surface: With application to ocean surface wave measurements

The technique for extracting wave period and wave direction from radar backscattering intensity is well developed, but the determination of spectral density or wave height is hindered by the complex nature of the modulation transfer function. In contrast to backscattering intensity, the Doppler signal of a coherent radar is originated from the radial velocity of the scattering objects. Its oscillatory component is contributed by ocean waves. The peak component of the Doppler velocity spectrum can be used to obtain the spectral peak wave period and the significant wave height can be calculated from the variance of the Doppler velocity. Analyses of coherent radar measurements collected from the ocean show that with radar range coverage on the order of 10 dominant wavelengths, a good estimate of peak wave period and significant wave height is achievable with radar data as short as a few seconds.