Abstract
Soil moisture is an important parameter for the terrestrial water, energy and carbon cycles. Measurement of the dielectric properties is critical for near-surface soil moisture estimation using microwave remote sensing. A number of empirical and semi-empirical models have been derived to describe the relationship. In this study, four widely-used soil dielectric models for soil moisture retrieval, the Wang-Schmugge model, the Dobson model, the Hallikainen model, and the GRMDM (generalized refractive mixing dielectric model) model were compared and the effect of uncertainties of them on soil retrievals were also investigated. Theoretical values of soil dielectric constant were calculated for three soil textures (60% sand, 20% clay; 30% sand, 30% clay; and 20% sand, 60% clay) with the four soil dielectric constant models. The effective soil dielectric constants calculated by models are seen to differ more as the sand content of soil increases. Errors induced by wrong soil texture may exceed 10% for the worst case. The results indicate that the errors induced by the alternative dielectric mixing model may be over the standard accuracy requirement (4% volumetric soil moisture) in soil moisture retrievals.
Published Version
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