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Technical Note

L-Band SAR Co-Polarized Phase Difference Modeling for Corn Fields

1
Quantitative Remote Sensing Group, Institute of Astronomy and Space Physics (IAFE), Buenos Aires 1428, Argentina
2
Department of Physics, Engineering School, University of Buenos Aires (UBA), Buenos Aires 1428, Argentina
3
Signal Theory and Communications Department (TSC), Universitat Politècnica de Catalunya (UPC), 08034 Barcelona, Spain
*
Author to whom correspondence should be addressed.
Academic Editors: Takeo Tadono, Masato Ohki and Klaus Scipal
Remote Sens. 2021, 13(22), 4593; https://doi.org/10.3390/rs13224593
Received: 29 August 2021 / Revised: 9 November 2021 / Accepted: 11 November 2021 / Published: 15 November 2021
(This article belongs to the Special Issue ALOS-2/PALSAR-2 Calibration, Validation, Science and Applications)
This research aims at modeling the microwave backscatter of corn fields by coupling an incoherent, interaction-based scattering model with a semi-empirical bulk vegetation dielectric model. The scattering model is fitted to co-polarized phase difference measurements over several corn fields imaged with fully polarimetric synthetic aperture radar (SAR) images with incidence angles ranging from 20° to 60°. The dataset comprised two field campaigns, one over Canada with the Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR, 1.258 GHz) and the other one over Argentina with Advanced Land Observing Satellite 2 (ALOS-2) Phased Array type L-band Synthetic Aperture Radar (PALSAR-2) (ALOS-2/PALSAR-2, 1.236 GHz), totaling 60 data measurements over 28 grown corn fields at peak biomass with stalk gravimetric moisture larger than 0.8 g/g. Co-polarized phase differences were computed using a maximum likelihood estimation technique from each field’s measured speckled sample histograms. After minimizing the difference between the model and data measurements for varying incidence angles by a nonlinear least-squares fitting, well agreement was found with a root mean squared error of 24.3° for co-polarized phase difference measurements in the range of −170.3° to −19.13°. Model parameterization by stalk gravimetric moisture instead of its complex dielectric constant is also addressed. Further validation was undertaken for the UAVSAR dataset on earlier corn stages, where overall sensitivity to stalk height, stalk gravimetric moisture, and stalk area density agreed with ground data, with the sensitivity to stalk diameter being the weakest. This study provides a new perspective on the use of co-polarized phase differences in retrieving corn stalk features through inverse modeling techniques from space. View Full-Text
Keywords: synthetic aperture radar; polarimetric radar; co-polarized phase difference; radar scattering; vegetation; radar applications; agriculture synthetic aperture radar; polarimetric radar; co-polarized phase difference; radar scattering; vegetation; radar applications; agriculture
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MDPI and ACS Style

Barber, M.E.; Rava, D.S.; López-Martínez, C. L-Band SAR Co-Polarized Phase Difference Modeling for Corn Fields. Remote Sens. 2021, 13, 4593. https://doi.org/10.3390/rs13224593

AMA Style

Barber ME, Rava DS, López-Martínez C. L-Band SAR Co-Polarized Phase Difference Modeling for Corn Fields. Remote Sensing. 2021; 13(22):4593. https://doi.org/10.3390/rs13224593

Chicago/Turabian Style

Barber, Matías E., David S. Rava, and Carlos López-Martínez. 2021. "L-Band SAR Co-Polarized Phase Difference Modeling for Corn Fields" Remote Sensing 13, no. 22: 4593. https://doi.org/10.3390/rs13224593

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