Surface film effects on the radar cross section of the ocean surface

摘要: Ocean surface films, biogenic and/or hydrocarbon in nature, damp the gravity-capillary waves important for radar backscatter at microwave frequencies. Although petroleum and slicks have been observed by imaging radars on many occasions, there is no satisfactory model ocean RCS with films present. The author reports results a candidate model. Wave damping effects are introduced into calculation of waveheight spectrum term calculated according to approximate method Cini Lambardini viscoelastic data various drawn from work, Huhnerfuss his colleagues Hamburg University. wave height modification Durden Vesecky. effect sea temperature bulk viscosity water included. resulting spectra used note impact L- K/sub u/-band. Model indicate significant cross section reductions wind speed 5 m/s. For this simple /spl sigma//spl deg/ reduction increases monotonically frequency constant film type environmental observational conditions. Predicted vary over 0 10 dB range depending temperature. Results compared observations several types artificial five frequency, helicopter mounted, operated Wismann finds that surface-film-wave damping, acting only as loss spectral model, can not account properly reductions. Thus, it concluded better must include driven source wave-wave interaction.