COMPARISON OF DIRECTIONAL REFLECTANCE AND RADAR BACKSCATTER FROM DESERT SURFACES, THE EASTERN BADIA OF JORDAN

George Mackay1	1 Department of Geography, University of Leicester, Leicester, LE1 7RH, UK. e-mail: gm20@le.ac.uk
Kevin Tansey1	e-mail: kjt7@le.ac.uk
Andrew Millington1	e-mail: acm4@le.ac.uk
Kevin White2	2 Department of Geography, University of Reading, Reading, RG6 2AB, UK. e-mail: k.h.white@geography.rdg.ac.uk

Abstract

In this paper we present preliminary results of an investigation into the relationship between optical directional reflectance properties and surface roughness. We also compare the measure of optical roughness obtained from field spectroradiometer measurements for surfaces in the eastern desert of Jordan with the corresponding radar backscatter coefficient from ERS-1 SAR data. A measure of the optical roughness is assumed using the ratio, R, of the slope to the intercept determined in a simple linear fit of directional reflectance expressed as a function of phase angle. Observations demonstrate that R increases linearly as a function of the rms surface height. The implication of this work is that optical directional reflectance data could be used in conjunction with SAR data to constrain surface roughness estimates in a multisensor approach to retrieve surface environmental parameters. Further studies are planned to assess the robustness of R as an indicator of surface roughness and the sensitivity to the single scattering albedo, atmospheric turbidity, and solar elevation.

Keywords: surface roughness, directional reflectance, ERS SAR, desert surfaces.

Keywords: ESA European Space Agency - Agence spatiale europeenne, observation de la terre, earth observation, satellite remote sensing, teledetection, geophysique, altimetrie, radar, chimique atmospherique, geophysics, altimetry, radar, atmospheric chemistry