Bidirectional reflectances of selected desert surfaces and their three-parameter soil characterization

Abstract Spectral bidirectional reflectances were measured over three natural alkali soil sites using a specially designed radiometer called the Portable Apparatus for Rapid Acquisition of Bidirectional Observations of Land and Atmosphere (PARABOLA). Two of the sites were void of vegetation with different surface characteristics (alkali flat and dune sand flat), while the third had a sparse cover of desert scrub. The reflectances were strongly non-Lambertian for all three surfaces, but with markedly different patterns. The measured data were fitted with a quasi-physical reflectance model in which the surface backscattering and forwardscattering are separately formulated. A soil reflectance characterization was obtained by assessing the fractional contributions of the forward, backward and Lambertian components. For the desert scrub surface the backscattering component was larger by a factor of 10 or more than the forwardscattering component and by a factor of about two larger than the Lambertian component. The alkali flat backscatter component was little more than half the magnitude of the Lambertian component, and the dune sand was characterized by a forwardscatter component more than double the backscatter component. This three-parameter characterization produced a satisfactory fit to the measured reflectances. Since the component values remain relatively constant at different sun angles, this approach appears very promising as a basis for soil patterns or terrain categorization based on their anisotropic reflectance patterns.

[1]  Elizabeth M. Middleton,et al.  Surface anisotropy and hemispheric reflectance for a semiarid ecosystem , 1987 .

[2]  G H Weiss,et al.  Reflection from a field of randomly located vertical protrusions: errata. , 1984, Applied optics.

[3]  Piers J. Sellers,et al.  Inferring hemispherical reflectance of the earth's surface for global energy budgets from remotely sensed nadir or directional radiance values , 1985 .

[4]  Thomas F. Eck,et al.  Atmospheric optical depth effects on angular anisotropy of plant canopy reflectance , 1987 .

[5]  D. Deering,et al.  A sphere-scanning radiometer for rapid directional measurements of sky and ground radiance: The PARABOLA field instrument , 1984 .

[6]  Vincent V. Salomonson,et al.  Airborne measurements of reflected solar radiation , 1971 .

[7]  D. Kimes.  Dynamics of directional reflectance factor distributions for vegetation canopies. , 1983, Applied optics.

[8]  S. Gerstl,et al.  Radiation physics and modelling for off-nadir satellite sensing of non-Lambertian surfaces , 1986 .

[9]  L. Biehl,et al.  Variation in spectral response of soybeans with respect to illumination, view, and canopy geometry , 1984 .

[10]  Daniel S. Kimes,et al.  Diurnal variations of vegetation canopy structure , 1983 .

[11]  Narendra S. Goel,et al.  Bidirectional canopy reflectance and its relationship to vegetation characteristics , 1989 .

[12]  J. Otterman.  Reflection from soil with sparse vegetation , 1981 .

[13]  Kriebel Kt,et al.  Measured spectral bidirectional reflection properties of four vegetated surfaces. , 1978 .

[14]  F. Eaton,et al.  Reflected irradiance indicatrices of natural surfaces and their effect on albedo. , 1979, Applied optics.

[15]  J. Otterman.  Satellite and field studies of man's impact on the surface in arid regions , 1981 .

[16]  J. Otterman,et al.  Satellite Measurements of Surface Albedo and Temperatures in Semi-Desert , 1985 .

[17]  Jerzy Cierniewski.  The influence of the viewing geometry of bare rough soil surfaces on their spectral response in the visible and near-infrared range , 1989 .

[18]  D. Diner,et al.  MISR: A multiangle imaging spectroradiometer for geophysical and climatological research from Eos , 1989 .

[19]  F. E. Nicodemus,et al.  Geometrical considerations and nomenclature for reflectance , 1977 .