Doppler spectrum of radio wave scattering from ocean-like moving surfaces for a finite illuminated area

• Published in: International journal of remote sensing 2003-01, Vol.24 (15), p.3075-3091
• Main Author: Hisaki, Y.
• Format: Article
• Language: English
• Subjects: Applied geophysics; Earth sciences; Earth, ocean, space; Exact sciences and technology; Internal geophysics; Marine geology
• ISSN: 0143-1161; 1366-5901
• DOI: 10.1080/01431160210153057

It is necessary to understand how the Doppler peak frequency in the Doppler spectrum of radio wave scattering from moving waves is determined for practical applications such as oceanographic remote sensing. The author investigated Doppler peak frequency by using the integral equation method (IEM) for V-V polarization and a one-dimensional surface and by calculating the Doppler spectra of backscattered signals at moderate incidence for a finite illuminated area. In some cases, the Doppler peak frequency in Doppler spectra are determined from the surface wave frequency and not from the phase velocity of the surface wave, if the illuminated area is finite. The author investigated scattering from a sinusoidal wave for various radar and wave parameters. Doppler peaks were revealed at wave frequencies and higher-order harmonics of the Doppler peaks appeared in most cases. However, Doppler peaks whose position was close to the wave phase velocity-Doppler frequency became dominant as the phase difference of the reflected radio wave within the illuminated area became smaller. The appearance of wave phase velocity-Doppler peaks was limited when quasi-coherent scattering dominated. This interpretation can be applied to Bragg scattering, for which the Bragg wave phase velocity-Doppler frequency is exactly equal to the wave frequency of the Bragg wave.