Passive and active microwave remote sensing of soil moisture under a forest canopy

Active and passive microwave remote sensing of soil moisture is compared at L-band for forested covered terrain. Data collected in Howland, Maine during the Forest Ecosystem Dynamics (FED) experiment in 1990 have been used to validate a discrete scatter model. The model is then used in a series of parameter studies to extrapolate the results to canopies with a wide range of biomass and surface conditions. The objective of this study is to gain insight into the range of biomass over which soil moisture can be measured by the two sensors. Tree and surface parameters are varied to generate different biomass and ground conditions. Both radar and radiometer exhibit sensitivity to soil moisture under a wide range of conditions. How these sensitivities diminish with increasing biomass and surface roughness is an important factor in the response of both sensors