Record Details

Prospects of the ICESat-2 Laser Altimetry Mission for Savanna Ecosystem Structural Studies Based on Airborne Simulation Data
External Online Source: doi:10.1016/j.isprsjprs.2016.04.009
Author and Affiliation:
Gwenzi, David(Colorado State Univ., Dept. of Ecosystem Science & Sustainability, Fort Collins, CO, United States);
Lefsky, Michael A.(Colorado State Univ., Dept. of Ecosystem Science & Sustainability, Fort Collins, CO, United States);
Suchdeo, Vijay P.(Sigma Space Corp., Greenbelt, MD, United States);
Harding, David J.(NASA Goddard Space Flight Center, Greenbelt, MD United States)
Abstract: The next planned spaceborne lidar mission is the Ice, Cloud and land Elevation Satellite 2 (ICESat-2), which will use the Advanced Topographic Laser Altimeter System (ATLAS) sensor, a photon counting technique. To pre-validate the capability of this mission for studying three dimensional vegetation structure in savannas, we assessed the potential of the measurement approach to estimate canopy height in an oak savanna landscape. We used data from the Multiple Altimeter Beam Experimental Lidar (MABEL), an airborne photon counting lidar sensor developed by NASA's Goddard Space Flight Center. ATLAS-like data was generated using the MATLAS simulator, which adjusts MABEL data's detected number of signal and noise photons to that expected from the ATLAS instrument. Transects flown over the Tejon ranch conservancy in Kern County, California, USA were used for this work. For each transect we chose to use data from the near infrared channel that had the highest number of photons. We segmented each transect into 50 m, 25 m and 14 m long blocks and aggregated the photons in each block into a histogram based on their elevation values. We then used an automated algorithm to identify cut off points where the cumulative density of photons from the highest elevation indicates the presence of the canopy top and likewise where such cumulative density from the lowest elevation indicates the mean terrain elevation. MABEL derived height metrics were moderately correlated to discrete return lidar (DRL) derived height metrics r(sub 2) and RMSE values ranging from 0.60 to 0.73 and 2.9 m to 4.4 m respectively) but MATLAS simulation resulted in more modest correlations with DRL indices r(sub 2) ranging from 0.5 to 0.64 and RMSE from 3.6 m to 4.6 m). Simulations also indicated that the expected number of signal photons from ATLAS will be substantially lower, a situation that reduces canopy height estimation precision especially in areas of low density vegetation cover. On the basis of the simulated data, there is reason to believe that the ability of ICESat-2 to estimate height in savannas will be comparable to the original ICESat mission although the respective sensors have different measurement principles.
Publication Date: May 10, 2016
Document ID:
20170003204
(Acquired Apr 19, 2017)
Subject Category: EARTH RESOURCES AND REMOTE SENSING
Report/Patent Number: GSFC-E-DAA-TN41051
Document Type: Journal Article
Publication Information: ISPRS Journal of Photogrammetry and Remote Sensing (ISSN 0924-2716); Volume 118; 68-82
Publisher Information: Elsevier
Financial Sponsor: NASA Goddard Space Flight Center; Greenbelt, MD United States
Organization Source: NASA Goddard Space Flight Center; Greenbelt, MD United States
Description: 15p; In English
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: Copyright
NASA Terms: OPTICAL RADAR; ICE, CLOUD AND LAND ELEVATION SATELLITE; LASER ALTIMETERS; ECOSYSTEMS; SIMULATION; PHOTONS; ELEVATION; CANOPIES (VEGETATION); AIRBORNE EQUIPMENT; BIOPHYSICS; BIOMASS; CARBON; OPTICAL MEASURING INSTRUMENTS
Availability Source: Other Sources
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