Measurement and modeling of steep ocean wave slopes and absolute calibration of the radar altimeter

The frequently cited work of Cox and Munk is reviewed to highlight their inference that sea surface slopes often exceed what one would predict using a Gaussian assumption for the slope probability density function (pdf). The importance and validity of this observation is then discussed within the context of near-nadir microwave radar backscatter measurements. The authors illustrate the nearly direct analogy and quantitative agreement between Cox and Munk´s glitter estimation technique and that of airborne radars operating at 14 and 36 GHz. The demonstration points out the error and confusion that can arise in slope variance estimation when the Gaussian assumption is invoked in radar data analysis. Moreover, the study suggests a robust approach for absolute calibration of the satellite radar altimeter through use of the angular dependence of near-nadir radar observations