APPLICATIONS OF SPACEBORNE RADAR LABORATORY DATA TO THE STUDY OF AEOLIAN PROCESSES

Aerodynamic roughness (z(0)) is an important parameter in studies of s and and dust transport, as well as atmospheric circulation models. Aer odynamic roughness is a function of the size and spacing of surface ro ughness elements and is typically determined at point locations in the field from wind velocity profiles. Because field measurements require complex logistics, z(0) values have been obtained for very few locali ties. If radar can be used to map z(0), estimates can be obtained for large areas. In addition, because aerodynamic roughness can change in response to surface processes (e.g., flooding of alluvial surfaces), r adar remote sensing could obtain new measurements on short timescales. Both z(0) and the radar backscatter coefficient sigma(0) are dependen t on topographic roughness at the submeter scale, and correlation betw een these two parameters was developed based on radar data obtained fr om aircraft (AIRSAR). The Spaceborne Radar Laboratory (SRL) afforded t he opportunity to test the correlation for data obtained from orbit. S RL data for sites in Death Valley, California; Lunar Lake, Nevada; and Gobabeb, Namibia, were correlated with wind data and compared with pr evious radar z(0) relations. Correlations between sigma(0) and z(0) fo r L band (lambda = 24 cm) HV (H, vertically and V, vertically polarize d modes) L band HH, and C band (lambda = 5.6 cm) HV compare favorably with previous studies. Based on these results, maps of z(0), values we re derived from SRL data for each site, demonstrating the potential to map z(0) for large vegetation-free areas from orbit using radar syste ms.