A dielectric model at a frequency of 1.4GHz for frozen mineral soils in the temperature range −1 to −30°C

Abstract

A single-frequency dielectric model at 1.4 GHz for frozen mineral soils was developed, with the temperature and clay content varying from −1 to −30°C and 9.1 to 41.3%, respectively. The model is based on dielectric measurements of three typical soils (sandy loam, silt loam, and silty clay) collected in the Yamal peninsular. The refractive mixing model was applied to fit the data aggregates consisting of measured complex refractive indexes (CRI) for the three soils as a function of soil moisture at a fixed temperature. As a result, there were derived the parameters of the refractive mixing dielectric model as a function of temperature and texture. These parameters involve the maximum allowed gravimetric fraction of bound water and the CRIs of soil solids, bound soil water, and free soil water components, the latter being represented by capillary ice. The error of the dielectric model was evaluated by correlating the predicted complex relative permittivity (CRP) values of the soil samples with the measured ones. The coefficient of determination, R2, and the root mean square error, RMSE, were estimated to be R2 = 0.994, RMSE = 0.22 and R2 = 0.988, RMSE = 0.07 for the real and imaginary parts of the CRP, respectively. These values are on the order of the dielectric measurement error itself. The proposed dielectric model can be applied in active and passive remote sensing techniques used in the Arctic areas, mainly for the SMOS, SMAP and Aquarius missions.