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

Abstract

[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,

Polarimetric analysis of radar backscatter from ground-based scatterometers and wheat biomass monitoring with advanced synthetic aperture radar images

“…An F-test was used to verify the extraction accuracy. 33,34 The average values of the measured biomass are 0.42 and 4.14 kg∕m 2 , and of the retrieved biomass are 0.39 and 3.74 kg∕m 2 August 5, 2009, in the research, which were lower than the critical value 3.79, so the retrieved parameters were not significantly different from the measured values. …”

“…However, the backscattering coefficients on the 145th growth day are smaller than those on the 115th growth day, which demonstrates that the wheat canopy contributed more to the backscatter attenuation. The soil moisture is 30.5% and 27.6% on the 145th and 165th days, respectively, and the values of biomass, LAI, and weight and length of wheat ears increase by 1.06 kg∕m 2 , 0.99, 1.11 kg∕m 2 , and 4.6 cm, respectively. The backscattering coefficients on the 165th day are larger than those on the 145th day, which shows that the backscatter returned directly from the wheat canopy increases because volume scattering dominates the total backscatter.…”

“…Consequently, analyzing the radar backscatter characteristics of wheat has become an active research field in recent years. 1,2 Further, backscatter modeling of wheat and biomass retrieval from SAR images has also been attributed great attention by the researchers. [3][4][5][6] Scatterometers have been used to measure and analyze vegetation scattering characteristic because of their associated ease of use.…”

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Engineering Concepts in Stem Cell Research

“…They concluded that this technique was promising for vascular tissue engineering. [113] Additionally, scaffolds for fabrication and/ or regeneration of body organs (such as heart, liver, and kidney) and the nervous system (including the spinal cord and brain) have been developed. [114] Akhavan et al developed rolled graphene oxide foam (GOF) layers as an electrical conductive 3D scaffold for differentiation of human neural stem cells (hNSCs) that are useful in neural tissue engineering.…”