Mapping surface mineralogy and scattering behavior using backscattered reflectance from a hyperspectral midinfrared airborne CO2 laser system (MIRACO2LAS)

• Published in: IEEE transactions on geoscience and remote sensing 1999-07, Vol.37 (4), p.2019-2034
• Main Authors: CUDAHY, T. J, WHITBOURN, L. B, CONNOR, P. M, MASON, P, PHILLIPS, R. N
• Format: Article
• Language: English
• Subjects: Applied geophysics; Earth sciences; Earth, ocean, space; Exact sciences and technology; Internal geophysics
• ISSN: 0196-2892; 1558-0644
• DOI: 10.1109/36.774713

Airborne, high-spectral resolution, thermal-IR (TIR) MIRACO2LAS reflectance data were evaluated for mapping surface mineralogy and scattering behavior for a variety of semi-arid, geological test sites in Australia. MIRACO2LAS is a rapidly tuned, airborne CO2 laser system that measures backscattered (bidirectional) reflectance at 100 wavelengths between 9.1 and 11.2 microns for 2-m footprints in line profile mode. An operational methodology is described that permits reduction of the raw airborne signal-to-ground reflectance. Comparisons between the airborne MIRACO2LAS spectra and laboratory directional hemispherical reflectance (DHR) spectra show the same spectral shapes, though differences in average reflectance occur for some types of rocks. Based on an empirical relationship between the minimum and maximum reflectance established using laboratory DHR spectra, a method is proposed that allows the use of MIRACO2LAS data to identify surfaces that are characterized by Lambertian or specular scattering. The MIRACO2LAS results show that Lambertian-type scatterers include soils and many types of isotropic rocks. Specular-type scatterers include water and anisotropic rocks. This ability to map a given pixel's scattering behavior has implications for temperature-emissivity separation in passive TIR data, as MIRACO2LAS can be used to provide an independent estimate of emissivity, provided the surface is judged to be a Lambertian scatterer. (Author)