A relationship between radar backscatter and aerodynamic roughness: Preliminary results

The ability of the wind to move particles and the flux of windblown sand are both dependent on the topographic roughness of the surface, as measured by the aerodynamic roughness (zo). For most surfaces, topographic roughness controls many of the characteristics of the radar return, and the magnitude of the radar backscatter can be regarded as a measure of the surface roughness at or near the wavelength scale. Radar backscatter data may therefore be useful in obtaining a value of aerodynamic roughness which can be used to assess aeolian sediment transport via remote sensing. In this study, calibrated LHH, CHH and KuVV radar data were used to derive characteristic backscatter coefficients (σo) for three lava flow units, an alluvial fan, and a playa surface. Preliminary analyses show that values of σo and zo both increase with topographic roughness and that there is a good correlation between the two coefficients. This correlation suggests that it may be possible to assess aerodynamic roughness directly from radar data.