Spectral Unmixing Applied to Desert Soils for the - Naval ...

The absorption feature band depths for the ~500 nm, 1125 nm, and 2200 nm
features are 0.0232, 0.0176, and 0.0304 for burnt clay (Table 1). The field road clay
values were 0.052, 0.0193, 0.0745, gate clay values 0.057, 0.021, 0.0645, gopher till
values 0.0419, 0.026, 0.073, home hill clay values 0.092, 0.0087, 0.137, and hard picnic
area clay values 0.0805, 0.154, 0.000 (flat) are for 500 nm, 1125nm, and 2200 nm,
respectively (Table 1). The continuum removed values are representative of the depths of
the absorption features at each wavelength calculated using (5) and (6), and are thought
to be associated with how the soil components are altered with various levels of
disturbance. As previously mentioned, Clark and Roush (1984) discussed how the use of
the continuum removed function allows one to analyze a spectrum that is not heavily
influenced by the processes of other minerals in a mixture or those within the mineral
itself. Therefore, the depths of the absorption features and the changes occurring
amongst them must be related to some change in the intrinsic properties of the soils
themselves, as was suggested by Prose (1985) and postulated by this study.
Table 1. This table lists the absorption feature depths for each soil spectrum
using the continuum removed function and the deepest portion of the
feature. The values listed show changes in the depth of features for the
same material under different disturbance conditions for wavelengths of
~500 nm, 1125 nm, and 2200 nm. The depths are ordered by least to
greatest disturbance and show, for the most part, a trend of decreasing
depth, increasing depth, and decreasing depth at 500 nm, 1125 nm, and
2200 nm, respectively.
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