Errors in Radar Measurements of the Sea-Surface Large-Scale Slopes Due to the Sea-Wave Nonlinearity

Abstract

We analyze the errors of retrieving the variance of the large-scale slopes of the sea surface from the microwave sounding data. The errors caused by the slope-distribution deviations from the Gaussian distribution are considered. The model of the Cox–Munk probability-density function is used for analysis. The average relative error of calculating the variance from the nadir-sounding data amounts to 12%. When calculating the slope variances using the sounding data in the case of several incidence angles, the error depends on choosing the incidence-angle range. In this case, the relative error of determining the sea-surface slope variance amounts to 10–20%. Deviations of the sea-surface slope distributions from the Gaussian distribution lead to underestimated calculated values of the slope variance for both nadir and oblique sounding.