Estimation of Soil Moisture with Dual-Frequency - PALS

The purpose of this study is to evaluate whether the NASA/JPL dual frequency airborne system, Passive Active L-band and S-band (PALS), can provide a reliable soil moisture measurements so that they can be integrated to provide soil moisture data at the scales of the spaceborne coarse resolutions. Through evaluations of the AIEM simulated the random rough surface emissivities with a wide range of soil moisture and roughness conditions at both L-band and S-band, it was found that the bare surface emission signals at above two frequencies are essentially close to identical regardless of the surface soil moisture and roughness properties when the effect of soil properties (temperature and moisture) in the vertical profile on emission signals is minor. This makes it possible to further estimate the vegetation components in the omega-tau model at each frequency and polarization and to carry out the corrections for the vegetation effects without assumption on polarization dependence of the vegetation effects. Thus, the surface soil moisture can be inferred by the estimated surface emission signals. We will show the evaluation and validation of this technique with the airborne PALS measurements obtained during SMEX´02 soil moisture experiment with the intensive ground soil moisture measurements.