Modeling and analysis of bistatic scattering from forests in support of soil moisture retrieval

Bistatic Scattering Forward Model Validation Using GNSS-R Observations

“…Therefore, in order to compute the 𝝈 𝑹𝑹 and 𝝈 𝑳𝑹 , first our forward bistatic scattering model will be used to predict the radar cross section values corresponding to the linearly polarized received signal (𝝈 𝑯𝑯 , 𝝈 𝑽𝑽 ), and then equations ( 5) and ( 6) will be utilized to derive the cross section values related to the circularly polarized incident and scattered waves (𝝈 𝑹𝑹 , 𝝈 𝑳𝑹 ). For the case of scattering in the non-specular direction we will follow the same approach described above, however, we need to use the absolute value of co-polarization scattering elements of scattering matrix in lieu of reflection coefficients, namely (S 𝑯𝑯 , S 𝑽𝑽 ) [4][5].…”

“…Global land surface observations of soil moisture are essential for better understanding of how water, carbon, and energy cycles are linked. Soil moisture mapping has crucial impacts on many areas of human interest including weather and climate forecasting, wildfire and flood prediction, agriculture and drought analysis, and human health [1][2][3][4][5]. Soil moisture can be retrieved using active or passive microwave observations.…”

“…Therefore, it is important to advance novel soil moisture retrieval techniques by using the available SoOp from these sources [6][7][8][9][10][11][12]. In our previous works [3][4][5], a fully bistatic scattering forward model for vegetated terrain has been developed, which provides the possibility to exploit SoOp for soil moisture retrieval over various land covers including forests. The proposed bistatic scattering model has three main scattering mechanisms: direct ground scattering, vegetation volume scattering, and double bounce scattering from ground and vegetation layer.…”

“…The proposed bistatic scattering model has three main scattering mechanisms: direct ground scattering, vegetation volume scattering, and double bounce scattering from ground and vegetation layer. It also includes the Right-Hand Circularly Polarized (RHCP) incident and linearly polarized scattered wave cases [3][4][5]. The RHCP GNSS incident waves produce both RHCP (𝝈 𝑹𝑹 ) and Left-Hand Circularly Polarized (LHCP) scattered waves (𝝈 𝑳𝑹 ) upon reflection from the ground surface.…”

GNSS-R Soil Moisture Retrieval for Flat Vegetated Surfaces Using a Physics-Based Bistatic Scattering Model and Hybrid Global/Local Optimization

“…Using them enables retrieving scattered field measurements via passive receiver systems, which are simpler and less expensive than the monostatic radars and have the potential to provide more accurate soil moisture retrievals with higher spatial and temporal resolution. Studies recently focused on the use of signals of opportunity (SoOp) for addressing the soil moisture observation challenges on local and global scales [12,13].…”