Passive and Active Multiple Scattering of Forests Using Radiative Transfer Theory With an Iterative Approach and Cyclical Corrections

Salim, Maryam; Tan, Shurun; Roo, R.D. De; Colliander, Andreas; Sarabandi, Kamal

doi:10.1109/tgrs.2021.3082137

Cited by 5 publications

(7 citation statements)

References 51 publications

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“…In each iteration, a further order of scattering is incorporated through a numerical integration of the product of the phase matrix and the microwave intensity. The iterative approach enables separations of individual contributions to microwave intensity from each scattering order and scattering mechanism, allowing for a comprehensive assessment of multiple scattering effects in vegetated land surfaces [10], [11], [29].…”

Section: A a Brief Review To The Rt Theory And The Numerical Iterativ...mentioning

confidence: 99%

“…The microwave electromagnetic scattering models for vegetated land surfaces can be categorized into full wave analysis based approaches [4]- [8] and radiative transfer (RT) theorybased approaches [9]- [11]. The full wave method considers the interaction of coherent waves between the vegetation, taking into account the impact of vertical structure and horizontal distribution characteristics of plants.…”

Section: Introductionmentioning

confidence: 99%

“…The effect of multiple scattering in vegetated land surfaces is analyzed by solving higher-order solutions to RT equations. Existing models obtain the higher-order solutions to RT equations through several methods including the numerical iterative approach [10], [11], [21], the discrete coordinate method with eigenvalue analysis [22], [23], and the matrix doubling method [9], [16]. The numerical iterative approach is adopted in this work following our recent study [24].…”

Section: Introductionmentioning

confidence: 99%

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A Multiple-Scattering Microwave Radiative Transfer Model for Land Emission with Vertically Heterogeneous Vegetation Coverage

Chen,

Tan

2024

Preprint

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A multiple scattering model for passive radiative transfer (RT) in vegetation that accounts for the vertical profile of the plant structure is developed, offering advancements over the commonly-used single-layer uniform scattering models prevalent in the vegetated land surface microwave remote sensing. The proposed model takes into account the complexities of the canopy morphology with vertical heterogeneity, enabling the representation of overlapping vegetation species applicable to diverse plant types and growth stages. Additionally, it serves as a valuable tool for understanding the influence of the vegetation vertical structure on the microwave brightness temperatures. The model is constructed based on high-order solutions to the RT equations, obtained through a numerical iterative approach with an efficient interpolation scheme for algorithm acceleration. This methodology facilitates the accurate distinction of the contributions to the brightness temperature from each scattering order and scattering mechanism, ensuring a comprehensive consideration of multiple scattering effects within various vegetated scenarios. The model is validated using the SMAPVEX12 L-band forest data set, encompassing a wide range of soil moisture variations. Comparisons are made between the brightness temperatures simulated by the newly developed multiple-scattering model with a continuous profile or layered profile and those obtained from a uniform single-layer model. Results demonstrate significant improvements in the multi-layered or the continuously profiled model, showing improved agreement with the measured brightness temperatures. Furthermore, the proposed model is parameterized by matching the high-order solutions to the RT equation to the widely adopted reduced order albedo-tau formalism. The resulting equivalent parameters are linked to the geometries and the electromagnetic properties of the vegetation layer, while also incorporating the effects of multiple scattering. Comparative analysis of the equivalent parameters derived from the layered model and those derived from the single-layer model reveals that the vertical heterogeneity of the vegetation structure has a notable influence on the effective scattering albedo and it yields a value more consistent with the albedo as chosen in the SMAP/SMOS inversion algorithms. Meanwhile, the impact of the vegetation vertical profile on the effective optical thickness and the effective transmissivity of the vegetation layer is weak. These insights are essential for the retrieval of soil moisture and vegetation characteristics including the plant vertical structures in microwave remote sensing.

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Section: A a Brief Review To The Rt Theory And The Numerical Iterativ...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A Multiple-Scattering Microwave Radiative Transfer Model for Land Emission with Vertically Heterogeneous Vegetation Coverage

Chen,

Tan

2024

Preprint

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“…The dielectric constants of tree parts can be estimated with empirical formulas [7,[47][48][49][50]. The effective dielectric constant of each voxel can be determined by applying proper mixing formulas to the constituent matters within the voxel.…”

Section: Parameters For Tomosar Simulationsmentioning

confidence: 99%

“…Wildfire risk increases as the soil dehydrates [4] or more dry bushes pile up [5]. L-band and C-band radars have been used to estimate the moisture content in the leaves, branches and trunks of trees [6], by detecting their dielectric constants [7].…”

Section: Introductionmentioning

confidence: 99%

High-Resolution L-Band TomoSAR Imaging on Forest Canopies with UAV Swarm to Detect Dielectric Constant Anomaly

Chuang,

Kiang

2023

Sensors

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A rigorous TomoSAR imaging procedure is proposed to acquire high-resolution L-band images of a forest in a local area of interest. A focusing function is derived to relate the backscattered signals to the reflectivity function of the forest canopies without resorting to calibration. A forest voxel model is compiled to simulate different tree species, with the dielectric constant modeled with the Maxwell-Garnett mixing formula. Five different inverse methods are applied on two forest scenarios under three signal-to-noise ratios in the simulations to validate the efficacy of the proposed procedure. The dielectric-constant profile of trees can be used to monitor the moisture content of the forest. The use of a swarm of unmanned aerial vehicles (UAVs) is feasible to carry out TomoSAR imaging over a specific area to pinpoint potential spots of wildfire hazards.

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An Efficient Multiple Scattering Solution to Radiative Transfer Equations in Strong Forward Scattering Environments for Vegetated Land Emission and its Representation Through an Equivalent Albedo-Tau Formalism

Chen,

Tan

2024

IEEE Trans. Geosci. Remote Sensing

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Passive and Active Multiple Scattering of Forests Using Radiative Transfer Theory With an Iterative Approach and Cyclical Corrections

Cited by 5 publications

References 51 publications

A Multiple-Scattering Microwave Radiative Transfer Model for Land Emission with Vertically Heterogeneous Vegetation Coverage

A Multiple-Scattering Microwave Radiative Transfer Model for Land Emission with Vertically Heterogeneous Vegetation Coverage

High-Resolution L-Band TomoSAR Imaging on Forest Canopies with UAV Swarm to Detect Dielectric Constant Anomaly

An Efficient Multiple Scattering Solution to Radiative Transfer Equations in Strong Forward Scattering Environments for Vegetated Land Emission and its Representation Through an Equivalent Albedo-Tau Formalism

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