Radar backscatter/biomass saturation: observations and implications for global biomass assessment

SAR sensors are being evaluated for application to global carbon modeling as a means of acquiring biomass data for vegetated ecosystems. While good correlations have been reported linking SAR backscatter to biomass, biomass saturation limits, or the point where backscatter no longer scales with biomass, have also been noted. This study examines two SAR and biomass data sets of forests with different canopy architectures for commonalties regarding backscatter/biomass saturation. The SAR data were collected using the same instrument and incidence angles. The effect of the saturation limits on the usefulness of SAR for making global biomass inventories was assessed by comparing the biomass limits to a global vegetation biomass map. The areal extent and total global biomass represented by ecosystems that exceed the biomass saturation level for each band are estimated