SAR for REDD
SAR for REDD
The ESA DUE Innovator III project "SAR for REDD" aims to provide satellite synthetic aperture radar (SAR) pre-processing and analyzing capabilities and tools for operational tropical forest monitoring to REDD countries and primarily in Africa.
The UN initiative Reducing Emissions from Deforestation and Forest Degradation, including conservation, sustainable management of forests and enhancement of forest carbon stocks (REDD+), is an effort to create a financial value for the carbon stored in forests, offering incentives for developing countries to reduce emissions from forested lands and invest in low-carbon paths to sustainable development. A necessity to implement REDD+ is a consistent and accurate monitoring, reporting and verification (MRV) system based on both remote sensing and in-situ measurements.
As persistent cloud cover in the humid tropics prevent reliable observations at any time with optical satellite sensors, cloud-penetrating SAR imagery has proven to be a useful tool for interoperability and/or to complement optical satellite forest monitoring systems. For forest applications, L-band SAR is generally better suited than C-band since its longer wavelength penetrates deeper into the forest canopy and thus, also provides more information on biomass. However, ESA’s freely available, fully operational Sentinel-1 CSAR since 2014 allows higher coverage and revisit frequencies to establish denser time-series with increased radiometric accuracy that balances the L-band advantages.
SAR pre-processing and analysis has not been at the reach for everybody and there is still a strong need for technical and human capacity in developing countries for this sensor type to be fully used. Since the 1990s, Norut has developed automatic SAR pre-processing tools, analysis and operational SAR-based monitoring systems, able to process the main historical and current SAR sensors: ERS-1&2 SAR, Envisat ASAR, ALOS Palsar (1&2), Radarsat-2 and Sentinel-1.
In this project, Norut therefore not only provides already processed remote sensing products in the form of radiometric calibrated and geo-referenced SAR images, regional mosaics, forest/non-forest maps and forest change maps for specific periods, but also provides those necessary tools for mosaicking, temporal averaging and classification to enhance the technical capacity in tropical countries. This will give REDD countries the possibility to process and analyze historical and future SAR imagery and implement SAR into their operational forest monitoring systems to improve their monitoring, reporting and verification of REDD activities.
Interoperability and complementarity with optical remote sensing will be investigated benefitting from the SPOT5/TAKE5, Landsat-8 and Sentinel-2 programs. The project also includes a validation field campaign where forest parameters, ground and aerial photography will be collected. User workshops are planned insure human capacity building and the technical implementation of the SAR processing tools at the user’s premises.
The pilot focus region is the Mai-Ndombe district in the Democratic Republic of Congo and the service user is the Observatoir Satellitale des Forêts d’Afrique Centrale (OSFAC), a Congolese NGO that has been a close collaborator and partner to Norut since 2010. OSFAC’s primary objective is to support the management of natural resources and promote sustainable development by producing reliable land cover products, distributing satellite data, building capacity and providing technical assistance to implementing partners. Among those partners are the environmental ministries of several Congo Basin countries which are responsible for the REDD implementation and development of tropical forest monitoring systems in these countries.