Impact of Soil Structure on Microwave Volume Scattering Evaluated by a Two-Dimensional Numerical Model

Abstract

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Theoretical Modeling and Analysis of L- and P-band Radar Backscatter Sensitivity to Soil Active Layer Dielectric Variations

“…To calculate direct backscattering and bi-static scattering from the surface, the Advanced Integral Equation Method (AIEM) [33] was implemented in the model. Similar to [35], in which soil clods are deemed as dominant scatters and modeled as deformed ellipses, we modeled soil scatters as ellipsoids with short to long axis ratio 0.8. Rayleigh Approximation [36] was applied to the ellipsoid particles to calculate the phase matrix of the soil layer.…”

“…The effects of soil volume scattering on radar or radiometer measurements at C-band or higher frequencies have been observed and modeled in a few studies [35,43]. The lower frequency L-and P-band observations, relative to C-and X-band, have deeper soil penetration depth and smaller volume scattering effects.…”

“…The lower frequency L-and P-band observations, relative to C-and X-band, have deeper soil penetration depth and smaller volume scattering effects. It is interesting to evaluate soil volume scattering effects for these two frequencies, especially for dry or frozen soil when volume scattering becomes more important [35,43]. For this purpose, we make a similar assumption as [35] that the soil medium is composed of fine earth and large soil particles, which are the primary elements of soil volume scattering.…”

“…It is interesting to evaluate soil volume scattering effects for these two frequencies, especially for dry or frozen soil when volume scattering becomes more important [35,43]. For this purpose, we make a similar assumption as [35] that the soil medium is composed of fine earth and large soil particles, which are the primary elements of soil volume scattering. Based on the FTSS, we evaluated soil volume scattering effects by considering one deep frozen layer with ellipsoid soil particles of varying sizes.…”

“…Parameters such as soil clod size, volume fraction and dielectric properties are described in [35]. As the diameter of the equivalent soil particle sphere increases from 5 mm to 15 mm, the volume backscattering at L-band VV polarization increases from a negligibly small value of −41.6 dB to −27.3 dB, which is still much lower than the direct backscatter (about −14.9 dB) from the air-soil interface.…”