Model Analysis of Backscatter and Emission from Vegetated Terrains

Ferrazzoli, P.; Solimini, D.; Luzi, G.; Paloscia, S.

doi:10.1163/156939391x00554

Cited by 29 publications

(4 citation statements)

References 18 publications

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“…It has been reported in studies by Ferrazzoli et al, [70], Macelloni et al, [71] and Marliani et al, [72] that backscatter from 'broad' leaved crops (e.g. potatoes) increased with an increase in biomass, whereas backscattering from 'narrow' leaved crops (e.g.…”

Section: Coherence and Intensity Change Analysismentioning

confidence: 94%

The Use of C- and L-Band Repeat-Pass Interferometric SAR Coherence for Soil Moisture Change Detection in Vegetated Areas

Barrett¹,

Whelan²,

Dwyer³

2012

TORMSJ

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Abstract:Soil moisture estimation studies using Synthetic Aperture Radar (SAR) routinely utilise only the amplitude part of the received echo. In this study, repeat-pass C-and L-band interferometric SAR coherence from 2007 -2009 was evaluated for the detection of surface soil moisture changes in the presence of vegetation using two different approaches. In the first analysis, the association between low coherence and large in situ soil moisture changes was investigated using 24 interferometric pairs and the decorrelation effects due to vegetation and weather were also assessed. Results reveal that, in very few cases soil moisture differences between acquisitions contributed to the signal decorrelation. For the majority of cases, particularly in C-band, the change in vegetation tended to be the predominant source of decorrelation, suppressing the influence of any soil moisture changes. The second analysis applied thresholds to both coherence and intensity data to determine if a coalesced coherence ( ) and intensity change ( 0 ) approach could improve detection of changes in measured soil moisture content. The aim was to test the usefulness of a > 0.3 and 0 > 1.5 dB thresholding approach to separate the effects of a vegetation change and a soil moisture change on the SAR signal. Results suggest that the approach improves the reliability of the soil moisture change detection although clearly limits the use of available image pairs. These analyses demonstrate the increased information the coherence adds to SAR studies over agricultural areas.

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Section: Coherence and Intensity Change Analysismentioning

confidence: 94%

The Use of C- and L-Band Repeat-Pass Interferometric SAR Coherence for Soil Moisture Change Detection in Vegetated Areas

Barrett¹,

Whelan²,

Dwyer³

2012

TORMSJ

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“…These schemes estimate the attenuation characteristics including volume absorption and scattering from the discrete scatterers of the vegetation elements. The contributions of the different scatterers are then combined by means of the double matrix method [4,20]. Representing vegetation as a single continuum element is only valid under certain conditions, whereas an ensemble of discrete scattering elements can provide a more correct representation of vegetation [4,15].…”

Section: Introductionmentioning

confidence: 99%

Modeling Microwave Emission from Short Vegetation-Covered Surfaces

et al. 2015

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Owing to the temporal and spatial variability of the emissivity spectra, problems remain in the interpretation and application of satellite passive microwave data over vegetation-covered surfaces. The commonly used microwave land emissivity model, developed by Weng et al. (2001) and implemented into the community radiative transfer model (CRTM), treats vegetation-covered surfaces as a three-layer medium. This simplification comes at the cost of accuracy. In this study, to reduce bias in the modeling of microwave emissions from short vegetation-covered surfaces, two modifications are made. First, vegetation was considered as a multilayered medium including leaves and stems to simulate volumetric absorption and scattering. The results suggest that the calculated brightness temperatures well agree with field experiments under different incidence angles for low soil moisture and sparse crop cover. On the other hand, large errors from the measurements are found for high soil moisture content and dense crop cover. Second, the advanced integral equation model (AIEM) was also used to improve the simulation of reflectivity from rough soil surfaces. Comparisons with field experimental data show that the determination coefficient between the calculated and measured brightness temperatures significantly increased and the root-mean-square errors OPEN ACCESSRemote Sens. 2015, 7 14100 remarkably decreased. The average improvement using the proposed approach is about 80% and 59% in accuracy for the vertical and horizontal polarization, respectively.

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“…In active microwave remote sensing of soil moisture through vegetation, analyseis of the backscatter data acquired by ground-based radars were usually carried out by microwave discrete vegetation models based on analytical wave formulation [6][7][8][9] or phenomenological radiative transport theory [10][11][12][13]. The uniform plane wave assumption for incident and scattered waves is often introduced in these models due mainly to simplicity, and the scattered power is usually represented in terms of backscattering coefficient, which is proportional to the ratio of far-field observation of backscattered power to incident power of plane wave illumination.…”

Section: Introductionmentioning

confidence: 99%

Backscatter measurements over vegetation by ground-based microwave radars

Kurum

O'Neill

2011

2011 XXXth URSI General Assembly and Scientific Symposium

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In the study of radar backscattering from vegetated terrain, it is important to understand how the electromagnetic wave interacts with vegetation and the underlying ground. In this paper, an expression of backscattering from a vegetation canopy in the case of spherical wave illumination is derived. Such an expression might apply to the practical case of a ground-based scatterometer overlooking vegetation. The relative importance of the beamwidth as well as the platform height on backscattering from vegetated terrain is studied. Preliminary results indicate that the discrepancy with plane wave illumination can be rather significant, and therefore should not be overlooked.

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Model Analysis of Backscatter and Emission from Vegetated Terrains

Cited by 29 publications

References 18 publications

The Use of C- and L-Band Repeat-Pass Interferometric SAR Coherence for Soil Moisture Change Detection in Vegetated Areas

The Use of C- and L-Band Repeat-Pass Interferometric SAR Coherence for Soil Moisture Change Detection in Vegetated Areas

Modeling Microwave Emission from Short Vegetation-Covered Surfaces

Backscatter measurements over vegetation by ground-based microwave radars

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