Radar Backscatter and Biomass Saturation: Ramifications for - Geoscience and Remote Sensing, IEEE Transactions on
نویسنده
چکیده
Two SAR and biomass data sets of forests with different canopy architectures were examined for commonalties regarding backscatterhiomass saturation. The SAR data were collected using the NASNJPL AIRSAR at incidence angles between 40’ and 50’ for tropical broadleaf evergreen forests in Hawaii and coniferous forests in North America and Europe. Radar signal saturation L i t s with respect to biomass for both forest types were determined to be nl00 tonsha for Pband (0.44 GHz), x40 tonsha for L-band (1.25 GHz), and n20 tonsha for C-band (5.3 GHz). The effect of the saturation limits on making global biomass inventories with SAR sensors was aesessed by comparing the biomass saturation limits to a global vegetation type and biomass data base. C-band can be used to measure biomass in biomes covering 25% of the world’s total ice-free vegetated surface area accounting for 4% of Earth’s store of terrestrial phytomass. Land P-band can be used to measure biomass in biomes covering 37% and 62% of the total vegetated surface area accounting for 8% and 19% of Earth’s pool of terrestrial phytomass respectively. Biomes occupying approximately 38% of Earth’s vegetated surface area containing 81% of the estimated total terrestrial phytomass have biomass densities above the saturation limit of current SAR systems (>lo0 tondha for P-band). Since P-band radar systems cannot currently operate effectively from orbit, the use of SAR sensors for biomass surveys may be limited even further to the L-band threshold. Emphasis should be shifted toward using SAR to characterize forest regeneration and development up to the saturation limits shown here rather than attempting to measure biomass directly in heavy forests. The development of new and innovative technologies for measuring biomass in high density vegetation is encouraged.
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