Simulating radar altimeter waveforms for precise retrieval of sea surface parameters

The simulation of radar altimeter echoes is a fundamental tool to set up an accurate ground processor for estimating ocean parameters. This paper arises from a thesis work(1) based on the simulation approach proposed by Tateiba and Fujita,(2,3) It is. based on the specular point approximation of the electromagnetic scattering problem bur in principle it does not require assumptions on the properties of the random surface and the transmitted signal. The more critical aspect of the proposed solution is the identification of the specular points within the area illuminated by the antenna that requires to impose the orthogonality among a generic optical ray emerging from the antenna and the local plane tangent to the surface. In this paper, we have reconsidered the mentioned approach. In particular, we have refuted the method to search the specular paints in order to improve its efficiency, We have tested the implementation of the algorithm for an isotropic Gaussian surface and compared the results to the waveforms derived by using the "Brown model"(4). We have also retracked the simulated waveforms using a processing software developed by Telespazio S.p.A(5,6) as a first attempt to use the simulator within an accurate processing chain for altimeter data. Moreover we have compared the statistics of the echo to what is expected from a completely developed speckle.