SWIMSAT: A real-aperture radar to measure directional spectra of ocean waves from space - Main characteristics and performance simulation

The project SWIMSAT aims to measure the directional spectra of waves from s pace using a real-aperture radar with a low-incidence, conical-scanning bea m. This system's design is based on airborne versions developed in France a nd the United States. In this paper, the authors present the satellite meas urement principle and instruments. For this study, the authors developed a simulation method to analyze the sensitivity of wave spectra, taking into a ccount radar observation conditions (spatial resolution, signal-to-noise ra tio, integration time, etc.) and inversion processing parameters (noise lev el and range displacements during temporal integration). The simulation met hod and results are presented in this paper. The study enabled validation a nd refinement of the satellite concept. The simulations show that in the ch osen configuration, SWIMSAT is capable of measuring wave spectral propertie s in wind-sea conditions (at dominant wavelengths over approximately 70 m) and swell conditions (at significant wave heights over approximately 1.5-2 m, depending on wind). Unlike for synthetic aperture radar observations, th e performance of SWIMSAT in terms of minimum detectable wavelength is indep endent on the wave propagation direction.