Field observations of radar backscatter modulation and radar Doppler shifts in slicks

Polarimetric Doppler spectrum of backscattered echoes from nonlinear sea surface damped by natural slicks

“…• showed that Doppler shifts in slicks can increase or decrease, depending on radar wavelength and surface film characteristics [47,48]. It should be noted that our simulations are limited to L-band (1.2 GHz) due to the severe computational burden encountered in large-scale Monte Carlo simulations, while the open ocean experiments were performed at X-and Ka-bands [47,48]. Hence, our simulation results cannot be fairly compared with the measurements [47,48].…”

“…• was investigated by using an empirical formula of Doppler spectral bandwidth [46], indicating also that at low to moderate wind speeds the Doppler spectrum width in slicks is In the open ocean experiments carried out in 1997-1998 on the Black Sea [47,48], it was indicated that the variations of Doppler shifts in slicks is very complicated. The VV-polarized radar measurements performed at X-and Kabands with fixed incidence angle 55…”

“…It should be noted that our simulations are limited to L-band (1.2 GHz) due to the severe computational burden encountered in large-scale Monte Carlo simulations, while the open ocean experiments were performed at X-and Ka-bands [47,48]. Hence, our simulation results cannot be fairly compared with the measurements [47,48]. In addition, at wind speed 7-9 m/s, a strong reduction of Doppler shifts in slicks at X-band is observed in the wind-wave tank measurements performed at incidence angle of 35…”

“…The simulation results show that the Doppler shifts in slicks can decrease or increase, which depends on polarizations and incidence angles. The open ocean experiments carried out in 1997-1998 on the Black Sea performed at X-and Ka-bands with fixed incidence angle indicated that Doppler shifts in slicks can increase or decrease, which depends on radar wavelength and surface film characteristics [47,48]. In addition, at wind speed 7-9 m/s, a strong reduction of Doppler shifts in slicks at X-band is observed in the wind-wave tank measurements performed at incidence angle of for VV polarization [45].…”

Wave tank studies of radar Doppler shifts in the presence of surfactant films on the water surface

“…The effect of radar backscatter depression in organic slicks is the most pronounced for X-, Ku-and Ka-band radars, however, the damping degree is almost insensitive to physical parameters of films (e.g., to the film elasticity). Recently a new effect was revealed in our field experiments [2,3]. It was shown that Ka-band and X-band radar Doppler shifts were changed in slicks compared to nonslick areas, and the effect depended strongly on the film elasticity.…”