Electromagnetic Backscattering from a Layer of Vegetation: A Discrete Approach

Lang, Roger H.; Sighu, Jagjeet S.

doi:10.1109/tgrs.1983.350531

Cited by 231 publications

(79 citation statements)

References 13 publications

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“…The Numerical Maxwell Model in 3 Dimensions [23,24] is adopted as the benchmark model for the bare surface. A "discrete scattering" approximation approach [25,26] is utilized for the non-woody vegetated surface, and a layered scattering geometry and vegetation model [27] are applied for the woody vegetated surface. Three channels radar backscattering coefficients, HH, HV and VV, as well as auxiliary data (including DEM, land cover class and crop type, etc.…”

Section: Smap Sm Productsmentioning

confidence: 99%

Multi-Scale Validation of SMAP Soil Moisture Products over Cold and Arid Regions in Northwestern China Using Distributed Ground Observation Data

Long

et al. 2017

Remote Sensing

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Abstract:The Soil Moisture Active Passive (SMAP) mission was designed to provide global mapping of soil moisture (SM) on nested 3, 9, and 36 km earth grids measured by L-band passive and active microwave sensors. The validation of SMAP SM products is crucial for the application of the products and improvement of the retrieval algorithm. Since the SMAP SM products were released, much effort has been invested in the evaluation of the SMAP radiometer SM product (SMAP_P). However, there has been little validation of SMAP radar (SMAP_A) and active/passive combined (SMAP_AP) SM products. This paper presents an evaluation of SMAP_P, SMAP_A and SMAP_AP SM products by using distributed ground observations networks in different landscapes in the Heihe River Basin of northwestern China. The standard error metrics of SMAP products and relative error are applied to measure the products' performances. The results show that the SMAP SM products exhibit consistent spatial-temporal variation with the ground measurements and typical precipitation events. Three products show various types of performance capability (e.g., active, passive and combined), surface coverage (e.g., bare, vegetated) and climatic region (e.g., cold, arid). Relatively, the SMAP_P shows the best performance, while the SMAP_A performs the worst. The best performances are observed over bare soils but with overestimation and the largest relative error, and unsatisfactory accuracies are observed over cold regions and woody vegetated surfaces with underestimation. The vegetation effect and the freezing-thawing cycle may be major factors that led to an unsatisfactory performance. Efforts on resolving the influence of these factors are expected to improve the accuracy and to promote the application of SMAP SM products over these regions. Overall, this evaluation provides an understanding of SMAP SM products over cold and arid regions, and suggestions for the further refinement of the SMAP SM retrieval algorithms.

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Section: Smap Sm Productsmentioning

confidence: 99%

Multi-Scale Validation of SMAP Soil Moisture Products over Cold and Arid Regions in Northwestern China Using Distributed Ground Observation Data

Long

et al. 2017

Remote Sensing

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“…Electromagnetic scattering from the forest is an important remote sensing problem for agricultural and environmental purposes [29,30]. For the microwave radar frequencies considered in this paper, the trunks in a typical forest are separated by multiple wavelengths.…”

Section: Forest To Radar Scattering E F -Rmentioning

confidence: 99%

Analysis of Moving Human Micro-Doppler Signature in Forest Environments

Garcia-Rubia¹,

Kıłıc²,

Dang³

et al. 2014

PIER

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Abstract-Automatic detection of human motion is important for security and surveillance applications. Compared to other sensors, radar sensors present advantages for human motion detection and identification because of their all-weather and day-and-night capabilities, as well as the fact that they detect targets at a long range. This is particularly advantageous in the case of remote and highly cluttered radar scenes. The objective of this paper is to investigate human motion in highly cluttered forest medium to observe the characteristics of the received Doppler signature from the scene. For this purpose we attempt to develop an accurate model accounting for the key contributions to the Doppler signature for the human motion in a forest environment. Analytical techniques are combined with full wave numerical methods such as Method of Moments (MoM) enhanced with Fast Multipole Method (FMM) to achieve a realistic representation of the signature from the scene. Mutual interactions between the forest and the human as well as the attenuation due to the vegetation are accounted for. Due to the large problem size, parallel programming techniques that utilize a Graphics Processing Unit (GPU) based cluster are used.

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“…Suppose a plane wave given by (1) is illuminating the ground plane from the upper half-space, where is the unit vector along the propagation direction given by (2) The vector in (1) is expressed in terms of a local coordinate system ( , , ) where and denote the horizontal and vertical unit vectors, respectively. Representing the direction of the observation point by , the polarization of the scattered field can also be expressed in terms of a local coordinated system ( , , ) where (3) and and can be obtained using similar expressions as those given for and , respectively. …”

Section: Theoretical Analysismentioning

confidence: 99%

“…medium, and the single scattering theory was applied to account for the scattering and propagation in the random medium [1]- [3]. For example, in [1], a forest stand is represented in terms of a two-layer random medium, including a crown layer composed of randomly oriented cylinders and disks representing branches and leaves and a trunk layer containing nearly vertical cylinders representing tree trunks below the crown layer.…”

Section: Introductionmentioning

confidence: 99%

Electromagnetic scattering from short branching vegetation

Chiu

Sarabandi

2000

IEEE Trans. Geosci. Remote Sensing

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Abstract-A polarimetric coherent electromagnetic scattering model for short branching vegetation is developed in this paper. With the realistic structures that reasonably describe the relative positions of the particles, this model is able to consider the coherent effect due to the phase difference between the scattered fields from different particles, and account for the second-order, near-field interaction between particles, to which the relative positions and orientation of the particles are essential. The model validation with measurements is also presented, and excellent agreement is obtained. The polarimetric radar backscatter measurements for soybean plants using truck-mounted scatterometers were conducted at L-band and C-band under different soil-moisture conditions. Through an extensive ground truth, the important plant and rough surface parameters such as the soil moisture and surface roughness, vegetation dielectric constant, and geometry of the soybean plants, were characterized for model verification. It is found that the second-order near-field scattering is significant at C-band for fully grown soybeans due to the high vegetation particle density, and at L-band, the contribution from the second-order near field is negligible. The coherence effect is shown to be important at L-band and to a much lesser extent at C-band. This model is then used to demonstrate its ability for estimating the physical parameters of a soybean field, including soil moisture from a polarimetric set of AIRSAR images.

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Electromagnetic Backscattering from a Layer of Vegetation: A Discrete Approach

Cited by 231 publications

References 13 publications

Multi-Scale Validation of SMAP Soil Moisture Products over Cold and Arid Regions in Northwestern China Using Distributed Ground Observation Data

Multi-Scale Validation of SMAP Soil Moisture Products over Cold and Arid Regions in Northwestern China Using Distributed Ground Observation Data

Analysis of Moving Human Micro-Doppler Signature in Forest Environments

Electromagnetic scattering from short branching vegetation

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