Infrared measurements of pristine and disturbed soils 2. Environmental effects and field data reduction

We have expanded on previous methods for co,-rEding thermal infrared field measurements for atmospheric downwelling radiance (Salisbury and D'Aria, 1992; Korb et al., 1996; Hook and Kahle, 1996) by comparing the sensitivity of various input parameters (sample temperature, diffuse gold plate emissivity, and temperature) on this correction. We find that the sample temperature has the greatest influence on the applied atmospheric correction (cf. Nerry et al., 1990a,b; Labed and Stoll, 1991), and we present a method in which the sample temperature is varied to minimize the residual atmospheric emission liner in the measured field emissivity spectra. Direct comparison of laboratory hemispherical reflectance measurements of wet-sieved and dry-sieved samples with these appropriately corrected field observations of undisturbed and disturbed soils, respectively, provides a means to predict the expected infrared spectral contrast differences between such soils (see preceding article). (C) Elsevier Science Inc., 1998.