National Aeronautics and Space Administration

National Climate Assessment

NASA National Climate Assessment (NCA) Activities

NASA Centers Call for Proposals

National Climate Assessment - 2011 NASA Centers Call For Proposals

Lead PI and Center: Christopher Potter, Ames Research Center
Title:  CASA-CQUEST Modeling for Carbon Cycle Assessments in Forested Ecosystems of the United States
Proposal type: Assessment Capabilities & Products
Project website:
News article about research:
NCA project publications:


Over the past three years, this project has developed new satellite image dataset inputs to carbon cycle models for understanding how ecosystem carbon dioxide exchange and forest land cover has been affected by climate trends since the 1980s. Both Landsat and MODIS vegetation index time series have been utilized to accomplish these assessments across all of North America, with special emphasis on California and Alaskan ecosystem change. For example, Potter (2014) reported a detailed geographic record of recent vegetation regrowth and disturbance patterns in forests of the Sierra Nevada mountains with Landsat Thematic Mapper (TM) imagery. TM data was analyzed to detect recent changes in forest vegetation cover for areas burned by wildfires between years of 1995 and 1999 in the region. Results confirmed the prevalence of regrowing forest vegetation during the period over 17% of the forest burned areas. In general, the NASA Ames group has shown that Landsat and MODIS time series analysis can fulfill much of the need for consistent, low-cost monitoring of changes due to climate and biological factors in US forests that are regrowth following stand-replacing disturbances.


CASA model

(Left) CASA model monthly predictions of net ecosystem CO2 flux closely matches AmeriFlux eddy-correlation monthly estimates at (a) Atqasuk wetland, (b) Ivotuk shrubland, (c) Delta Junction forest of Alaska; (Right) CASA model prediction of mean net ecosystem CO2 flux over Alaska for the years 2000 to 2010. The relatively warm and wet years of 2004 and 2007 resulted in the highest positive CO2 flux totals northern and western coastal zones in the state (i.e., the Brooks Range Mountains and Arctic Foothills). Potter et al. 2013. Ecosystems (in review).

The CASA (Carnegie-Ames-Stanford Approach) model and CQUEST (Carbon Query and Evaluation Support Tools) are already in use nationwide for development of spatially explicit data for carbon sequestration and greenhouse gas (GHG) emission assessments in U. S. forested lands. CASA-CQUEST modeling has focused increased attention on regional scales of carbon fluxes.

Proposed Effort:
The CASA model will be applied at NASA Ames Research Center using MODIS 1-km resolution satellite data inputs for the Enhanced Vegetation Index (EVI) and forested land cover from the year 2000 to the present. CASA will predict changes in forest NPP (positive = CO2 sequestration rate, negative = CO2 emission rate). Annual carbon sink or source fluxes from all forested lands in the continental US will be quantified. Pools of wood and soil biomass carbon will be predicted based on the best available stand age and disturbance survey data sets. We will carry out statistical analysis of recent patterns in forest production across each U. S. forest region, with reference to both environmental variables (elevation, slope, aspect, soils, etc.) and human management (protected areas, logging practices, wildfire/suppression, etc.).

This project will produce and deliver assessment products on forest carbon and GHG fluxes, including appropriate coordination with NCA and other agencies. CASA-CQUEST will provide analyses of existing satellite sensor data sets and NASA models, as well as support scenario creation and assessment products from other state and federal agencies. The project will deliver freely available on-line visualization services to support analysis and communication of results for the NCA. The Principal Investigator will participate in the technical input, writing, and/or development of relevant section(s) of the 2013 NCA.


Map of Alaska showing trends in the monthly MODIS Enhanced Vegetation Index (EVI) time-series over the past decade (2000-2010). Green pixels identify vegetated areas that have become more productive as they are warming most rapidly over the past decade.  Results showed that 7% of all tundra-dominated areas in Alaska were detected with positive MODIS growing season EVI trends. Potter et al. 2013, J. of Geophysics & Remote Sensing, 2:107.

This assessment will address the overarching question of which variables are most closely associated with high sustained forest production and sinks for CO2 over the past decade, and which variables are most closely associated with unsustained forest production and large annual sources fluxes of CO2. CASA-CQUEST will thereby provide an ongoing, national-scale, consistent capability to assess current and projected carbon fluxes and climate-related risks to carbon storage in all forested lands of the U.S. CASA assessments will enable land owners and managers anywhere in the U. S. to

  1. plan carbon management activities more economically and effectively, now and in the future,
  2. design new activities to optimize production (food and fiber) needs, and
  3. meet resource conservation and GHG reductions goals previously unobtainable. When considering ecological services of soil, water and biodiversity, users will be able to query information of old-growth forests, woody stand composition, regeneration from fire, and all related carbon sequestration rates.
  4. CASA-CQUEST will uniquely support national GHG scaling issues, as well as understanding system interactions between mitigation and adaptation.

Project Publications:

Potter, C. S., 2014, Ten years of forest cover change in the Sierra Nevada detected using Landsat satellite image analysis, International Journal of Remote Sensing, 35: 7136–7153.

Potter, C., 2014, Geographic analysis of burn severity for the 2013 California Rim Fire, Natural Resources, 5, 597-606, doi:10.4236/nr.2014.511052.

Potter, C., 2014, Regional analysis of NASA satellite greenness trends for ecosystems of arctic Alaska, International Journal of Geosciences, 5, 997- 1006.

Potter, C. 2014, Regional analysis of MODIS satellite greenness trends for ecosystems of interior Alaska, GIScience & Remote Sensing, 51, 390-402.

Potter, C., S. Klooster, and V. Genovese, 2013, Alaska ecosystem carbon fluxes estimated from MODIS satellite data inputs from 2000 to 2010, Carbon Balance and Management, 8:12.

Potter, C., 2013, Ten years of land cover change on the California coast detected using Landsat satellite image analysis: Journal of Coastal Conservation, 10.1007/s11852-013-0270-3.

Shupe, J., and C. Potter, 2013, Modeling Discharge Rates for the Merced River in Yosemite National Park, Journal of the American Water Resources Association, 1-10. DOI:10.1111/jawr.12124.

Potter, C., S. Li, and R. Crabtree, 2013, Changes in Alaskan tundra ecosystems estimated from MODIS greenness trends, 2000 to 2010, Journal of Geophysics & Remote Sensing, 2: 107, doi:10.4172/2169-0049.1000107.

Potter, C., S. Li, and C. Hiatt, 2012, Declining vegetation growth rates in the eastern United States from 2000 to 2010, Natural Resources, doi:10.4236/nr.2012.

Li, S. and C. S. Potter, 2012, Vegetation regrowth trends in post forest fire ecosystems across North America from 2000 to 2010, Natural Sciences, doi:10.4236/ns.2012.

Potter, C., S. Klooster, and V. Genovese, 2012, Net primary production of terrestrial ecosystems from 2000 to 2009, Climatic Change, doi:10.1007/s10584-012-0460-2.

Potter, C., S. Klooster, V. Genovese, C. Hiatt, S. Boriah, V. Kumar, V. Mithal, and A. Garg, 2012, Terrestrial ecosystem carbon fluxes predicted from MODIS satellite data and large-scale disturbance modeling, International Journal of Geosciences, doi:10.4236/ijg.2012.

Huntzinger, D.N., et al., 2012, North American Carbon Program (NACP) regional interim synthesis: Terrestrial biospheric model intercomparison, Ecological Modelling, 232, 144-157.

Li, S., and C. S. Potter, 2012, Patterns of aboveground biomass regeneration in post-fire coastal scrub communities, GIScience & Remote Sensing, 49, 182-201.