Modeling of radar scattering by aeolian desert landforms

Abstract

In order to identify the origin of the effect of anomalously narrowly-directional backscattering of radio waves (ANDBR) of the X-band in desert areas, the work describes a complex analysis of many years of research in the Sahara desert regions. According to the results of the analysis, which was carried out using the SAR radar data of the Envisat-1 satellite, results of contact measurements, weather conditions and taking into account modern theories, the characteristics of the scattering of radio waves by the aeolian landforms of the desert were modeled. A new model of anomalous backscatter is proposed, according to which the main scatterer towards the radar is a grid formed by the wind from electrified saltons and reptons at a height of 2–3 cm from the surface and repeating the landform of ripples and barchans. The new model made it possible to explain the main features of experimental studies of the ANDBR effect. Namely: the dependence of the normalized radar cross-section (NRCS) of the researched terrain on the near-surface wind speed up to 10 m/s with opposite directions of the wind and radar survey vectors, as well as with their mutual azimuthal deviation of ±45 degrees. By using the new model, satellite monitoring of the near-surfacelayer moisture of the Earth desert regions at 3 cm and 5.6 cm radio wave length swith radar viewing angles is proposed.
 Keywords: radar remote sensing, desert monitoring, anomalously narrowly-directional backscattering, sand electrified layer.