Remote Sensing of Ocean Significant Wave Height by Forward Scattering:Examples from L-Band Data.

摘要

This is the final report of a series of three on measurements of 1.3-GHz (L-band) electromagnetic wave, forward reflection coefficients of the ocean. The L-band line-of-sight path was chosen between a transmitter in an aircraft flying at constant altitude towards receiving horns mounted on the stabilized platform of a destroyer. Six days of data were obtained by flights off the Atlantic Coast in 1974. Wave heights were measured by an airborne laser profilometer. The measured L-band forward reflection coefficients followed Ament's theoretical curve as a function of apparent surface roughness (sigma sub w sin psi)/lambda for the small roughnesses encountered (< or = 0.1). A remote sensing method for significant wave height emerges from recasting Ament's theoretical expression into a series of curves vs grazing angle (psi), with wave height (sigma sub w) as a parameter. Plotting the measured reflection coefficients on this graph then yields significant wave height (4 sigma sub w) directly. The average spread in the values of sigma sub w predicted by this method is + 0.12 ft for values of sigma sub w from 0.4 to 0.9 ft. An FM-sweep system is proposed which should improve this accuracy. (Author)