ALBIOM (ALtimetry for BIOMass)

The ALBIOM project (ALtimetry for BIOMass) proposes to derive forest biomass using SAR Altimetry Data from the Copernicus Sentinel-3 (S3) Mission.

Biomass is at present monitored globally using optical satellites, SAR and LiDAR technology, but it is still poorly quantified in most parts of the world, and the satellite data currently exploited for this purpose are not enough to achieve the goal of global biomass mapping and monitoring with sufficient accuracy.

In this context, data from existing satellites but unexploited so far, capable of providing additional independent biomass information, have the potential for a very important role in global observation of biomass, advancing our understanding of the carbon cycle and management of forests, biodiversity and ecosystems.

The ALBIOM project combines:

• A modelling component, through the development of a Sentinel-3 altimeter backscattering simulator over vegetated areas, based on the existing state of the art modelling of the backscattering of Ku and C-band signals from vegetation, to establish the physical relationships between the backscattered signal from S3 altimeter and the different levels of biomass;
• An algorithm component, through the development of a suitable inversion algorithm for biomass estimation from S3 altimeter data, investigating both a simple method based on error minimization (i.e. derivation of analytical or empirical model function) and a more empirical Artificial Neural-Network (ANN) approach trained on the model outputs, or on a combination of model outputs and data;

A prototype biomass product is generated as final project output over specific sites of boreal and tropical forests and shared with a number of users to assess its validity.

ALBIOM is an innovative project, since both the use of Sentinel-3 SAR altimeter data to retrieve biomass and the generation of a Sentinel-3 SAR altimeter backscatter simulator over vegetated areas have not been accomplished before.

The outcome of such project will have an important scientific impact, as it can provide a new global biomass dataset derived from S3 altimetry, which could be integrated into existing high-resolution biomass products derived from data fusion methods.

The project would also open up new perspectives on the use of all the historical data from the past altimetry missions for biomass mapping.

Users potentially interested in the results of ALBIOM include environmental agencies, space agencies, private companies, and all the entities interested in bioenergy, deforestation and forest degradation, biodiversity conservation, and sustainable management of biomass resources.

This 12 month activity is led by Deimos Space UK with the participation of University of La Sapienza (IT) and Tor Vergata University (IT).

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Methods and Results

The developed Sentinel-3 SRAL altimeter waveforms simulator, obtained through the modification & merging of the Tor Vergata Vegetation Scattering Model (TOVSM) and the Soil And Vegetation Reflection Simulator (SAVERS), can simulate both bare soil and forest backscattered waveforms. 

Simulated signals have been compared to both innovative Sentinel-3 waveforms, provided by the G-POD SARvatore for Sentinel-3 service (now moved to the ESA Altimetry Virtual Lab on EarthConsole®), and official Sentinel-3 L2 products.

The analysis of results over different types of surfaces has shown that waveforms related to forested surfaces present at least two peaks, due to the top of canopy and the ground. The presence of topography may introduce other peaks in the waveforms making the identification of vegetation and topographic effects very challenging. Despite these composite patterns, the developed simulator proved its capability to reproduce the main characteristics of Sentinel-3 waveforms.

Citations

• De Felice Proia G.,Restano M., Comite D.,Clarizia M.P., Benveniste J., Pierdicca N. and Guerriero L., “AnElectromagnetic Simulator for Sentinel-3 SAR Altimeter WaveformsOver Land—PartI: Bare Soil,” in IEEE Transactions on Geoscience and RemoteSensing, vol. 60, pp. 1-11, 2022, Art no. 2007211, doi:10.1109/TGRS.2022.3210720.

• De Felice Proia G.,Restano M., Comite D.,Clarizia M.P., Benveniste J., Pierdicca N. and Guerriero L., “AnElectromagnetic Simulator for Sentinel-3 SAR Altimeter WaveformsOver Land—PartII: Forests,” in IEEE Transactions on Geoscience and RemoteSensing, vol. 60, pp. 1-10, 2022, Art no. 2007310, doi:10.1109/TGRS.2022.3210722.

• ESA Altimetry Virtual Lab: https://earthconsole.eu/wp-content/uploads/2022/03/SARvatore_br_singlepages_220315.pdf

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