Microwave remote sensing of soil moisture: elimination of texture effect

In view of the influence of soil texture on microwave radiation, an attempt is made to eliminate the textural effects on the microwave reflectivity/emission. To determine the appropriate soil moisture parameter that minimizes the textural influences on microwave radiation from soils, soil moisture is expressed in terms of gravimetric and volumetric units and percentage of field capacity (M_fc ) and is plotted individually against the microwave reflectivity of soils. Only when soil moisture is in volumetric units are the textural influences significantly reduced. Therefore, a parameter, termed the critical water content (W_c), that takes into account the bound-water content of soils is used. An empirical relation between the interpolated values of W_c and the wilting point of soils has been developed. The soil water content above the W_c of each soil is considered as effective water M_eff