Data Processing Technique for Deriving Soil Water Spectroscopic Parameters in Microwave

Abstract

In this paper, the technique employed in the generalized refractive mixing dielectric model (GRMDM) (1), (2) for soil water spectroscopic analysis is extended to include fitting the refractive mixing dielectric model to moist soil complex dielectric constant (CDC) data in the frequency domain, with a restricted number of volumetric moistures being available. To reach this goal, the refractive mixing dielectric model was fitted to the moist soil CDCs measured first at volumetric moistures in the range below the maximum bound water fraction (MBWF). At this phase of data processing, spectroscopic parameters, that is, static dielectric constant, relaxation time, and conductivity, relating to the bound soil water were derived, along with the values of CDCs relating to a dry soil. Further fitting in frequency domain to the CDCs of moist soil, measured in the range of free soil water moistures, yielded the values of MBWF, as well as the spectroscopic parameters related to the free soil water. After this final stage of data processing, a full set of the GRMDM spectroscopic parameter became available to insure CDCs prediction as a function of soil moisture and frequency. The technique was validated on the basis of correlating the predicted moist soil dielectric data to those measured.