Mean Return Waveform Computations of Rough Surface for Low-Altitude Radar Altimeter

The Brown model is a convolutional model for the backscattered return waveform from a rough surface of the traditional radar altimeter. However, the Brown model ignores the fluctuation of return power, which caused errors in the low-altitude radar altimeter applications. A modified mean return waveform computation method is given by the convolution with elevation. The method is compatible with the Brown model at high altitudes and can be used to retrieve surface roughness from low-altitude radar altimeter observations.