Quantitative retrieval of soil moisture content and surface roughness from multipolarized radar observations of bare soil surfaces

Abstract

A semiempirical polarimetric backscattering model for bare soil surfaces is inverted directly to retrieve both the volumetric soil moisture content M-upsilon and the rms surface height s from multipolarized radar observations. The rms surface height s and the moisture content M-upsilon can be read from inversion diagrams using the measurements of the cross-polarized backscattering coefficient sigma(vh)(0) and the copolarized ratio p(= sigma(hh)(0)/sigma(vv)(0)). Otherwise, the surface parameters can be estimated simply by solving two equations (sigma(vh)(0) and p) in two unknowns (M-upsilon and s). The inversion technique has been applied to the polarimetric backscattering coefficients measured by ground-based polarimetric scatterometers and the Jet Propulsion Laboratory airborne synthetic aperture radar. A good agreement was observed between the values of surface parameters (the rms height s, roughness parameter ks, and the volumetric soil moisture content M-upsilon) estimated by the inversion technique and those measured in situ.