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 f ield measurements for atmospheric downwelling radiance (Salisbury and D'Aria, 1992; Korb et al., 1996; Hook and Kahle, 1996) by comparing th e sensitivity of various input parameters (sample temperature, diffuse gold plate emissivity, and temperature) on this correction. We find t hat the sample temperature has the greatest influence on the applied a tmospheric correction (cf. Nerry et al., 1990a,b; Labed and Stoll, 199 1), and we present a method in which the sample temperature is varied to minimize the residual atmospheric emission liner in the measured fi eld emissivity spectra. Direct comparison of laboratory hemispherical reflectance measurements of wet-sieved and dry-sieved samples with the se appropriately corrected field observations of undisturbed and distu rbed soils, respectively, provides a means to predict the expected inf rared spectral contrast differences between such soils (see preceding article). (C) Elsevier Science Inc., 1998.