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Update of the National Biomass and Carbon Dataset 2000 using ALOS PALSAR L-band
Josef
Kellndorfer, WHRC, josefk@whrc.org
(Presenter)
Oliver
Cartus, WHRC, ocartus@whrc.org
Wayne
Walker, WHRC, wwalker@whrc.org
The availability of several national high-resolution (30m) Earth Observation datasets for year 2000 (SRTM, NLCD, MRLC Landsat data) represented a unique opportunity for producing baseline canopy height (CH) and aboveground biomass (AGB) maps for the entire conterminous US, the National Biomass and Carbon Dataset, NBCD2000. SRTM scattering phase center heights, NLCD and Landsat datasets were used as predictor layers in randomForest for predicting CH and AGB; FIA inventory data were used for model development and validation. A multi-scale validation resulted in an RMSE for AGB of 55 (plot-), 19 (hexagon-) and 14 t/ha (county-level). The feasibility of an update of NBCD using ALOS PALSAR L-band data was investigated. For the biomass retrieval with L-band (from~2007), a novel retrieval algorithm was adopted (Santoro et al., 2011; Cartus et al., 2012) that does not rely on the availability of field inventory data for model calibration. A semi-empirical model, calibrated for each intensity image, was inverted to estimate biomass from 655 PALSAR dual-polarization images covering the Northeastern US. Where possible, a multi-temporal combination of single-image estimates was performed. A comparison with NBCD generally confirmed the feasibility of the approach. While characterized by pronounced scatter at full (30m) resolution, the agreement of the ALOS and NBCD maps improved substantially when aggregating the maps to coarser pixel sizes. We found that for the AGB retrieval with L-band, four acquisitions or more were required since the results for single acquisitions were in many cases affected by the imaging conditions (e.g., precipitation). The feasibility of the L-band SAR-based AGB retrieval was further confirmed when comparing the ALOS maps to FIA county AGB estimates (RMSE=12.9 t/ha). The results pointed out the potential of the planned ALOS-2 and DESDynI-R L-band missions, which will provide for significantly improved multi-temporal coverage, for large-area forest biomass mapping.
Presentation Type: Poster
Session: Poster Session 1-A
(Tue 11:00 AM)
Associated Project(s):
Poster Location ID: 11
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