- Abstract The aerodynamic roughness length (z 0) is governed by surface roughness and is an important parameter in many surface and climate related processes. The transport of windblown particles is affected substantially by variations in surface roughness; yet, not much attention has been devoted to improving knowledge of this parameter. In this paper, it is demonstrated that radar backscatter can be used as an indication of variations in z 0 on a regional scale and, therefore, can improve the ability to assess the susceptibility of a given surface to aeolian processes. Field studies were conducted in the south-western desert of the United States, in which z 0 values were obtained by in situ measurements of the boundary layer wind profile. Those sites were also assessed by airborne radar. Correlation coefficients between the radar data and z 0 are between 0· 74 and 0· 81.