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To date, models describing the complex dielectric constant (CDC) of tundra soils with different contents of organic matter (more than 30%) in the P-band were poorly reported and not developed. In this letter, a refractive dielectric model for moist organic soils at a frequency of 435 MHz was developed. The model was developed on the basis of dielectric measurements of five samples of organic soils with different organic content from 35% to 80% and the soil moisture from air-dry to field capacity at a temperature of 20 °C. The developed model is a function of only two parameters, namely, the organic content by weight and volumetric soil moisture. The new model and future BIOMASS mission will be creating the bases for developing new soil moisture profile retrieving algorithms in the root zone. [ABSTRACT FROM AUTHOR]

The dielectric measurements were made for five organic soils taken from the tundra territories of Alaska, Yamal, and Taimyr, with the content of organic matter varying from 35% to 80%. The measurements were carried out in the temperature range from −30 °C to 25 °C, frequencies from 0.45 to 16 GHz and soil moisture from close to zero to the field moisture capacity. The refractive mixing model was applied to fit the measurements of the soil’s complex refractive index (CRI) as a function of soil moisture, with the values of temperature being fixed. As a result, a respective dielectric model was developed. The amounts of bound and transient water in the thawed and frozen soils were introduced as parameters of the developed model and derived as a function of temperature and content of soil organic matter. The other parameters which concern the CRIs of soil solids as well as bound, transient, and liquid soil water or ice components were derived as a function of temperature. The errors of the proposed model estimated in terms of the values of normalized root-mean-sqaure error for the real and imaginary parts of the soil complex relative permittivity appeared to be 6%–7% and 23%, respectively. The proposed dielectric model can be applied in active and passive remote sensing, in particular, for the SMOS, SMAP, and Aquarius missions after testing in ground-based experiments. [ABSTRACT FROM AUTHOR]

A single-frequency dielectric model for thawed and frozen Arctic organic-rich (80%–90% organic matter) soil was developed. The model is based on soil dielectric data that were measured over the ranges of volumetric moisture from 0.007 to 0.573\;\textcm^3/\textcm^3, dry soil density from 0.564 to 0.666\;\textg/cm^3, and temperature from 25 °C to -\mathbf30^\circ\mathbfC (cooling run), at the frequency of 1.4 GHz. The refractive mixing model was applied to fit the measurements of the soil’s complex refractive index (CRI) as a function of soil moisture, with the values of temperature being fixed. Using the results of this fitting, the parameters of the refractive mixing model were derived as a function of temperature. These parameters involve the CRIs of soil solids as well as bound, transient, and free soil water components. 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 (\mathbfR^\mathbf2) and the root-mean-square error (RMSE) were estimated to be \mathbfR^\mathbf2= \mathbf0.999, \mathbfRMSE = \mathbf0.27 and \mathbfR^\mathbf2= \mathbf0.993, \mathbfRMSE = \mathbf0.18 for the real and imaginary parts of the CRP, respectively. These values are in 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 areas with organic-rich soil covers, mainly for the SMOS, SMAP, and Aquarius missions. [ABSTRACT FROM PUBLISHER]