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|Analysis of Long Wave Infrared (LWIR) soil data to predict reflectance response
|Simms, Janet E.
Berney, Ernest S.
Harrelson, Danny W.
Corcoran, Maureen K.
Castellane, Raymond M.
Long wave infrared
|Geotechnical and Structures Laboratory (U.S.)
Engineer Research and Development Center (U.S.)
|ERDC/GSL TR ; 09-25.
Abstract: The spectral response of quartz is a phenomenon of interest to countermine technologies because of suspected disruption in spectral signature from disturbed soil during emplacement of landmines in the subsurface. The research was divided into two studies: data analysis using spectral information from the Advanced Spaceborne Thermal Emission and Reflection (ASTER) spectral library and a laboratory study using a Fourier transform infrared (FTIR) spectrometer. Spectral and mineralogical data for five major soil orders (Alfisol, Aridisol, Entisol, Mollisol, and Inceptisol) were acquired from the spectral library. Using these data, the relationship of the percentage of reflectance around the 8.2-μm quartz peak to the percentage of quartz in a soil was used to develop a linear regression model. The equations from this model predict the expected quartz peak reflectance for a soil of given quartz percentage. The predictive equations determined from the ASTER database can be modified based on quartz species and grain size to enable better prediction of expected reflectance from natural soils. The FTIR system was used to measure the spectral response of different forms of quartz, clays, and quartz-clay mixtures. The spectral results revealed that different species of quartz exhibit different reflectance spectra, suggesting that the quartz reflectance response of a given soil type will vary depending on its impurities and depositional history. Grain-size fraction plays an important role in influencing the magnitude of reflectance. From the pure quartz studied, as grain size decreased from particle diameters of 1180 μm to less than 300 μm, FTIR reflectance increased according to a logarithmic relationship.
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