Observations of radar backscatter at Ku and C bands in the presence of large waves during the Surface Wave Dynamics Experiment

Abshact — Ocean radar backscatter in the presence of large waves is investigated using data acquired with the Jet Propulsion Laboratory NUSCAT radar at K. band for horizontal and vertical polarizations and the University of Massachusetts C-SCAT radar at C band for vertical polarization during the Surface Wave Dynamics Experiment. Backscatter 2 data of ocean surfaces was obtained in the presence of large waves with significant wave height up to 5.6 m, In moderate-wind cases, effects of large waves are not detectable within the measurement uncertainty and no noticeable correlation between backscatter coefficients and wave height is found. Under high wave light wind conditions, backscatter is enhanced significantly at large incidence angles with a weaker effect at small incidence angles. Ba&catter coefficients in the wind speed range under consideration are comp~ed with model results which confirm the experimental observations. Variations of the friction velocity, which can give rise to the observed backscatter behaviors in the presence of large waves, are presented.