Towards pantropical structure and biomass mapping from fusion of GEDI and TanDEM-X data

Abstract:

A key objective of NASA’s Carbon Monitoring System (CMS) is the development of transparent and high Application Readiness Level (ARL) data products that achieve levels of precision and accuracy required by current carbon credit trading protocols. Tropical forests store the highest aboveground biomass densities, but existing biomass products have highest uncertainties in this region. Accurately mapping forest aboveground biomass across the tropics at high spatial resolution remains challenging. Here, we present progress on a new approach developed in collaboration with the German Aerospace Center (DLR) for accurately mapping current aboveground carbon stocks by fusion of measurements from the NASA Global Ecosystem Dynamics Investigation (GEDI) mission and the DLR TerraSAR-X/TanDEM-X (TDX) mission. We focus initially on Gabon, Africa, for the current GEDI epoch (2019-2020). First, we show large area mapping of canopy height at 1 ha spatial resolution by establishing a link between physical forest structure measured by GEDI lidar data (i.e. vertical canopy profiles) and TDX InSAR data (i.e. radar reflectivity profiles). Second, we show application of these canopy height data along with GEDI footprint estimates of biomass for wall-to-wall mapping of biomass and uncertainty using Generalized Hierarchical Model based inference, and then validate these maps using NASA LVIS biomass estimates from the AfriSAR campaign following the CEOS Land Product Validation protocol. Finally, we discuss our interaction with stakeholders through Forests 2020/Ecometrica and expected benefits for conservation and restoration efforts across the pantropics.