Modeling microwave interactions with crops and comparison with ERS-2 SAR observations

Cookmartin, G.; Saich, P.; Quegan, S.; Cordey, R.A.; Burgess-Allen, P.; Sowter, Andrew

doi:10.1109/36.841996

Cited by 94 publications

(64 citation statements)

References 18 publications

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“…At the beginning of this period, the NDVI reaches its maximum value (~0.85) and saturates; the crop height increases from 0.3 to 0.9 m. Maximal top soil moisture values are observed during this period, inducing only little inflection of the backscattering coefficients after the highest rainfall event of the beginning of year 2010 (45 mm). Based on a radiative transfer model, [51] confirms that at C-band the breakdown of scatter contributions is first dominated by the ground before being masked by leaves and stems. Finally, from day 140 until harvest, the backscattering coefficients increase by approximately 5 and 3 dB at X-and C-bands, respectively.…”

Section: Multi-frequency Temporal Behaviorsmentioning

confidence: 58%

“…As observed, the increase of radar signal during this period is not linked to the top soil moisture variations. The breakdown of scatter contributions is dominated by the ground, followed by vegetation with the development of different rapeseed organs (leaves, branches, petioles and pods) [22,51]. As for X-band, Figure 8(b) shows that the general trend observed for one field is conserved over twelve fields during the entire crop cycle.…”

Section: Multi-frequency Temporal Behaviorsmentioning

confidence: 75%

“…During this period, the decrease of the NDVI is well pronounced and values reaches 0.25 just before harvest. These behaviors are associated with an increase in crop absorption when vegetation is wet, and the opposite effect occurs when vegetation is drying, particularly with the VV polarization state [51]. Over this field, radar signal seems insensitive to the soil moisture variations.…”

Section: Hh Vvmentioning

confidence: 99%

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Monitoring Wheat and Rapeseed by Using Synchronous Optical and Radar Satellite Data—From Temporal Signatures to Crop Parameters Estimation

Fieuzal¹,

Baup²,

Marais-Sicre³

2013

ARS

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This paper investigates the sensitivity of multi-temporal SAR data acquired at different frequencies (X-, C-and L-bands), polarizations (HH, VV, VH and HV) and incidence angles (from 24˚ to 53˚) during the growing season of two winter crops (rapeseed and wheat). This study was part of a multi-sensor crop-monitoring experiment that was performed from February to November 2010 (MCM'10). During the experiment, dense series of satellite data were acquired in microwave, optical and thermal domains (more than 150 images were provided by TerraSAR-X, Radarsat-2 Alos, Formosat-2, Spot-4/5 and Landsat-5/7) were synchronous with ground measurements over an agricultural area located in southwestern France, near Toulouse. An angular normalization of radar signals is first performed for each crop type at X-and C-bands by using a dense temporal satellite series and the complementarity provided by microwave and optical data. The results show that the angular sensitivity of radar backscatter decreases with the increase of the vegetation index (from 0.4 dB.˚− 1 over bare soils to 0.05 dB.˚− 1 for fully vegetated fields). Lower angular sensitivity is observed at X-band (compared to C-band), and for the cross-polarized signal. Analyses of the temporal signatures of the radar backscatter show a well-marked signal dynamic at X-, C-and L-bands, depending on the crops and theirs associated phenological stages. During the stems elongation of wheat while the NDVI increases of 0.2, a dynamic of 10 dB is observed at X-band and at C-band with VV polarization. Interesting behaviors are also observed during the crop senescence with an increase of several dB (depending on the sensor configuration), while the NDVI decreases of 0.5. Over rapeseed, cross-polarized backscatters offer promising dynamic of 6 dB during the seed development, while the NDVI saturates at maximum values. The use of radar signals, in complement of optical, for crop parameters monitoring is achieved in terms of leaf area index and crop height estimations. Over rapeseed, best correlations between crop parameters and radar signals are obtained at C-band, by combining co-and cross-polarized backscatters (R 2 > 0.61). Over wheat, best results are achieved by using X-band data (R 2 > 0.64).

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Section: Multi-frequency Temporal Behaviorsmentioning

confidence: 58%

Section: Multi-frequency Temporal Behaviorsmentioning

confidence: 75%

Section: Hh Vvmentioning

confidence: 99%

See 1 more Smart Citation

Monitoring Wheat and Rapeseed by Using Synchronous Optical and Radar Satellite Data—From Temporal Signatures to Crop Parameters Estimation

Fieuzal¹,

Baup²,

Marais-Sicre³

2013

ARS

View full text Add to dashboard Cite

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“…The involvement of large number of variables and parameter make their inversion complicated and cumbersome task. For examples, Cookmartin [8] developed a multilayer second order radiative transfer model. The limitation of Cookmartin [8] model is that it needs the attenuation parameters of various layers and inversion of this formulation is quite complex to retrieve the crop variables.…”

Section: Introductionmentioning

confidence: 99%

“…For examples, Cookmartin [8] developed a multilayer second order radiative transfer model. The limitation of Cookmartin [8] model is that it needs the attenuation parameters of various layers and inversion of this formulation is quite complex to retrieve the crop variables. Picard [9] has developed multiple scattering coherent models for understanding C-band radar backscatter from wheat canopy.…”

Section: Introductionmentioning

confidence: 99%

A Radial Basis Function Approach to Retrieve Soil Moisture and Crop Variables From X-Band Scatterometer Observations

Prasad¹,

Kumar²,

Singh³

2009

PIER B

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Abstract-An outdoor crop-bed was prepared to observe scatterometer response in the angular range of 20 • to 70 • at VV-and HHpolarization. The soil moisture and crop variables like plant height, leaf area index and biomass of crop ladyfinger were measured at different growth stages of the crop ladyfinger. Temporal variation in scattering coefficient was found highly dependent on crop variables and observed to increase with the increase of leaf area index and biomass for both polarizations. In this paper, a novel approach is proposed for the retrieval of soil moisture and crop variables using ground truth microwave scatterometer data and artificial neural network (ANN). Two different variants of radial basis function neural network (RBFNN) algorithms were used to approximate the function described by the input output relationship between the scattering coefficient and corresponding measured values of the soil moisture and crop variables. The new Corresponding author: R. Prasad (rprasad1@rediffmail.com). 202Prasad, Kumar, and Singh model proposed in this paper gives near perfect approximation for all three target parameters namely soil moisture, biomass and leaf area index. The retrieval with minimal error obtained with the test data confirms the efficacy of the proposed model. The generalized regression network was observed to give minimal system error at a much lower spread constant.

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Multitemporal radar backscattering measurement of wheat fields using multifrequency (L, S, C, and X) and full‐polarization

et al. 2013

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[1] This paper presents the measurements of the backscattering coefficients over the wheat fields using an L-, S-, C-, and X-band scatterometer system during a whole period of wheat growth. The wheat field located at Qionglai County of China was measured during a wheat growing season from November 2010 to May 2011. Twelve experimental acquisitions (ground and radar data) were measured over the wheat field in a flat area at VV-, VH-, HV-, and HH-polarizations of L-, S-, C-, and X-bands, with the incidence angles ranging from 0°to 80°. Wheat biomass, canopy structure, leaf area index (LAI), soil moisture, and eco-physiological canopy variables were also collected to investigate the radar sensitivity. It shows that the HH measurements for wheat are higher than VV at each band after jointing, and the value of HH/VV is larger for lower frequency. The temporal variations of each band at selected incidence angles were compared with the wheat biomass, canopy height, LAI, and soil moisture. The correlations were analyzed between backscattering coefficients and wheat crop variables at 23°, 38°, 53°, and 68°, respectively. The results show that the backscattering coefficient has a strong correlation with biomass and LAI, especially for the HH-and cross-polarizations of L-band, and the radar backscatter signatures at high frequency (X-and C-bands) are sensitive to detect newly transplanted thin wheat seedlings at the high incident angle. These data can provide experimental evidence to allow for determining the growth status and/or condition of wheat by use of measured radar backscatters.Citation: Jia, M., L. Tong, Y. Zhang, and Y. Chen (2013), Multitemporal radar backscattering measurement of wheat fields using multifrequency (L, S, C, and X) and full-polarization, Radio Sci., 48, 471-481,

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Modeling microwave interactions with crops and comparison with ERS-2 SAR observations

Cited by 94 publications

References 18 publications

Monitoring Wheat and Rapeseed by Using Synchronous Optical and Radar Satellite Data—From Temporal Signatures to Crop Parameters Estimation

Monitoring Wheat and Rapeseed by Using Synchronous Optical and Radar Satellite Data—From Temporal Signatures to Crop Parameters Estimation

A Radial Basis Function Approach to Retrieve Soil Moisture and Crop Variables From X-Band Scatterometer Observations

Multitemporal radar backscattering measurement of wheat fields using multifrequency (L, S, C, and X) and full‐polarization

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