Field studies of aerodynamic roughness length

The aerodynamic roughness length (z₀) 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 z₀ 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 z₀ 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 z₀ are between 0·74 and 0·81.