Ground and Volume Decomposition as a Proxy for AGB from P-Band SAR Data

Abstract

In this work, the role of volume scattering obtained from ground and volume decomposition of P-band synthetic aperture radar (SAR) data as a proxy for biomass is investigated. The analysis here presented originates from the BIOMASS L2 activities, part of which were focused on strengthening the physical foundations of the SAR-based retrieval of forest above-ground biomass (AGB). A critical analysis of the observed strong correlation between tomographic intensity and AGB is done in order to propose simplified AGB proxies to be used during the interferometric phase of BIOMASS. In particular, the aim is to discuss whether, and to what extent, volume scattering obtained from ground/volume decomposition can provide a reasonable alternative to tomography. To do this, both are tested on P-band data collected at Paracou during the TropiSAR campaign and cross-validated against in-situ AGB measurements. Results indicate that volume backscattered power as obtained by ground/volume decomposition is weakly correlated to AGB, notwithstanding different solutions for volume scattering are tested, and support the conclusion that forest structure actually plays a non-negligible role in AGB retrieval in dense tropical forests.

Estimation of potato above-ground biomass based on unmanned aerial vehicle red-green-blue images with different texture features and crop height

“…At present, the four primary techniques used to enhance the accuracy of AGB estimates are (i) the synthetic aperture radar technique (Montesano et al, 2013(Montesano et al, , 2014, (ii) the laser intensity direction and ranging (LiDAR) technique (Cao et al, 2018;Hu et al, 2020), (iii) the narrowband hyperspectral technique (Filippi et al, 2014;Tao et al, 2020), and (iv) the crop-height model (CHM; Roth and Streit, 2018;Zhu et al, 2019a;Issa et al, 2020). Given the use of long-wavelength electromagnetic radiation, synthetic aperture radar remote-sensing techniques can penetrate the crop canopy and are not affected by weather conditions, which means that they overcome the problem of premature saturation of AGB estimates by optical remote-sensing VIs and are thus highly suitable for long-term monitoring of AGB for areas with high crop coverage (Banda and Tebaldini, 2020). Previous studies have confirmed that using the backscattering coefficient of synthetic aperture radar remote sensing produces highly accurate estimates of crop AGB for wheat (Han et al, 2019), maize (Hosseini et al, 2019), and rice (Yang et al, 2016).…”

“…Given the use of long-wavelength electromagnetic radiation, synthetic aperture radar remote-sensing techniques can penetrate the crop canopy and are not affected by weather conditions, which means that they overcome the problem of premature saturation of AGB estimates by optical remote-sensing VIs and are thus highly suitable for long-term monitoring of AGB for areas with high crop coverage ( Banda and Tebaldini, 2020 ). Previous studies have confirmed that using the backscattering coefficient of synthetic aperture radar remote sensing produces highly accurate estimates of crop AGB for wheat ( Han et al, 2019 ), maize ( Hosseini et al, 2019 ), and rice ( Yang et al, 2016 ).…”

The BIOMASS Level 2 Prototype Processor: Design and Experimental Results of Above-Ground Biomass Estimation

“…Volume separation can be obtained through model-based ground and volume decomposition techniques [33,34], although the decomposition does not have a unique solution and the preferred solution is obtained by imposing physical constraints on the model [35,36]. Interferometric ground cancellation [37] instead relies purely on geometry.…”

Introduction to Radar Scattering Application in Remote Sensing and Diagnostics: Review

“…When an electromagnetic wave passes from one medium to another, changing, therefore, refraction index, or when it strikes an object such as a radar target and it is reflected, it allows a polarization control to acquire knowledge of the characteristic information about the reflectivity, e.g., the orientation and shape of the reflecting object. In classical radars, i.e., amplitude-only radars, the information about a target is mainly obtained from the energy of the returned pulse; interferometric SAR exploits fully the phase and Doppler information, but not the polarization information of the electromagnetic vector wave-scatterer interrogation process [116][117][118][119].…”