Project Funding: 2005 - 2009

NRA: 2004 NASA: Carbon Cycle Science   

Funded by NASA

Abstract:
A major goal of the North American Carbon Program (NACP) is to develop a quantitative scientific basis for regional to continental scale carbon accounting to reduce uncertainties about the carbon cycle component of the climate system. In support of this goal, the overall objective of the proposed research is the quantification of terrestrial carbon stocks held in aboveground biomass at an unprecedented spatial resolution for the entire continental U.S. Given the highly complementary nature and quasi-synchronous data acquisition of the 2000 Shuttle Radar Topography Mission (SRTM) and the Landsat-based 2001 National Land Cover Database (NLCD), an exceptional opportunity exists for exploiting data synergies afforded by the fusion of these high-resolution data sources. Accurate area-based estimates of terrestrial biomass and carbon require biophysical measures that capture both horizontal and vertical vegetation structure. Whereas the thematic layers of the NLCD are suitable for characterizing horizontal structure (i.e., cover type, canopy density, etc.), SRTM provides information relating to the vertical structure, i.e., primarily height. Recent research from pilot study sites in Georgia and California has shown that SRTM height information, analyzed in conjunction with bald Earth elevation data from the National Elevation Dataset (NED), is highly correlated with vegetation canopy height, yielding r2 values of 0.86 and 0.76 (rms errors of 1.2 and 4.4 m), respectively. The fusion of SRTM, NLCD, and NED datasets will contribute to 1) innovative processing of SRTM data to reduce noise, and b) inverse model development for height and biomass estimation based on empirical regression analysis. The proposed modeling approach will be ecoregion-based, using NLCD mapping zones to control for vegetation structural and regional climatic conditions across the conterminous U.S. Given the national scope of this effort, a collaboration has been established with the national Forest Inventory and Analysis (FIA) Program of the USDA Forest Service which provides a nationwide network of over 150,000 regularly surveyed forest plots, some 52,000 of which were surveyed during the SRTM mission timeframe. Within mapping zones, stepwise regression modeling will be used to develop canopy height and volume/biomass relationships based on FIA survey data and the various remote-sensing input datasets. Ecoregional estimates of carbon stock will be derived in turn. Under the supervision of FIA Spatial Data Services staff, all regression models will be subject to extensive validation and error accounting using independent testing populations. The project is proposed in two phases. Phase I is a proof-of-concept phase where biomass and carbon estimates will be generated for six of the 66 NLCD mapping zones (10% of U.S. by area), each representing different ecoregions. Phase II extends the knowledge base acquired during Phase I to the remainder of the conterminous U.S. Key research topics to be considered as part of this project include: 1) sensitivity of SRTM to vegetation structure and limitations for modeling vegetation canopy height, 2) optical/radar data fusion for modeling of biomass and carbon stocks, 3) value and limitations of FIA for regression modeling, 4) variability of vegetation structure among ecoregions and its relationship to model transferability, and 5) operational procedure development for integrating FIA and remote sensing data at regional to national scales. In general, the proposed research focuses on development of remote sensing technologies and the optimization of national forest inventories, which the NACP views as “critical needs in the near-term” for enabling more rigorous carbon accounting practices. Generation of a “millennium” high-resolution ecoregional database of circa-2000 vegetation canopy height, aboveground biomass, and carbon stocks for the conterminous U.S. will provide an unprecedented baseline against which to compare data products from the next generation of advanced microwave and optical remote sensing platforms.

Publications:

Kellndorfer, J. M., Walker, W. S., LaPoint, E., Kirsch, K., Bishop, J., Fiske, G. 2010. Statistical fusion of lidar, InSAR, and optical remote sensing data for forest stand height characterization: A regional-scale method based on LVIS, SRTM, Landsat ETM+, and ancillary data sets. Journal of Geophysical Research: Biogeosciences. 115(G2). DOI: 10.1029/2009JG000997

Walker, W. S., Kellndorfer, J. M., Pierce, L. E. 2007. Quality assessment of SRTM C- and X-band interferometric data: Implications for the retrieval of vegetation canopy height. Remote Sensing of Environment. 106(4), 428-448. DOI: 10.1016/j.rse.2006.09.007

Walker, W. S., Kellndorfer, J. M., LaPoint, E., Hoppus, M., Westfall, J. 2007. An empirical InSAR-optical fusion approach to mapping vegetation canopy height. Remote Sensing of Environment. 109(4), 482-499. DOI: 10.1016/j.rse.2007.02.001

Kellndorfer, J., Walker, W., Pierce, L., Dobson, M., Fites, J., Hunsaker, C., Vona, J., & Clutter, M. (2004). Vegetation height estimation from Shuttle Radar Topography Mission and National Elevation Datasets. Remote Sensing of Environment, 93:339-358.

2013 NASA Terrestrial Ecology Science Team Meeting Poster(s)

• Update of the National Biomass and Carbon Dataset 2000 using ALOS PALSAR L-band   --   (Josef Kellndorfer, Oliver Cartus, Wayne Walker)   [abstract]

2011 NASA Carbon Cycle & Ecosystems Joint Science Workshop Poster(s)

• Biomass Mapping of US forests using synergy of SAR and optical Remote Sensing   --   (Josef Kellndorfer, Alessandro Baccini, Jesse B. Bishop, Oliver Cartus, Tina Cormier, Wayne S. Walker, Maurizio Santoro)   [abstract]

2010 NASA Terrestrial Ecology Science Team Meeting Poster(s)

• National Biomass and Carbon Dataset 2000: A High-Resolution Dataset for the Conterminous U.S. from InSAR/Optical Fusion   --   (Josef Kellndorfer, Wayne Walker, Katie Kirsch, Greg Fiske, Jesse Bishop, Elizabeth LaPoint, Michael Hoppus, James Westfall)   [abstract]

2008 NASA Carbon Cycle & Ecosystems Joint Science Workshop Posters

• The National Biomass and Carbon Dataset 2000: A High Spatial Resolution Baseline to Reduce Uncertainty in Carbon Accounting and Flux Modeling   --   (Josef Kellndorfer, Wayne Walker, Katie Kirsch, Greg Fiske, Jesse Bishop, Elizabeth LaPoint, Michael Hoppus, James Westfall)   [abstract]

More details may be found in the following project profile(s):

• NASA Terrestrial Ecology (TE) Project Profile
• North American Carbon Program (NACP) Project Profile