Estimation of the aerodynamic roughness length in arid and semi-arid regions over the globe with the ERS scatterometer

[1] Estimates of the aerodynamic roughness lengths z(0) in arid and semi-arid regions are for the first time provided for the whole globe, using satellite ERS scatterometer observations. A statistical relationship is derived between the ERS scatterometer backscattering coefficients and quality in situ and geomorphological z(0) estimates. It is a practical solution to provide realistic roughness maps with large-scale spatial patterns that are consistent with independent surface characterization. In addition, it makes it possible to analyze the seasonal and interannual variations of this parameter on a global basis. The satellite-derived surface roughness parameters have been implemented into the dust emission scheme of a global dust cycle model. Dust emission computations are improved when using the ERS derived z(0) as input parameter. The spatial correlation between the TOMS observation frequency and the model dust events increases from 0.34 when using fixed z(0) to 0.52 when using the satellite-derived estimates.