Near-Nadir Ka-band radar backscattering measurements over wate surfaces, in preparation of the swot mission

In order to support future altimetry space missions in Ka-band, an airborne campaign has been realized with the ONERA BUSARD platform and its DRIVE radar. The particularity of this campaign is the line of sight geometry, with very steep incidence angles, using a Ka-band SAR interferometer instrument. The area of interest was the Camargue region in south of France. Five flights were planned on dry and wet land surface and sea surface with different wind conditions. In this paper, we describe the context of the campaign, and the sensor configuration that has been used. We then present the areas that have been measured and show an example of aircraft trajectory. Finally, we present some images and interferometry products that have been acquired and produced at very steep angles (0-15° of incidence). In addition we expose some extracted backscattering coefficient profiles, as a function of the incidence angle. Nadir backscattered levels are close to values found in literature, and specular behavior is found on pond surfaces while more diffuse returns are observed over sea and ground surfaces.