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The BigFoot project gathered Net Primary Production (NPP) data for nine EOS Land Validation Sites located from Alaska to Brazil from 2000 to 2004. Each site is representative of one or two distinct biomes, including the Arctic tundra; boreal evergreen needleleaf forest; temperate cropland, grassland, evergreen needleleaf forest, and deciduous broadleaf forest; desert grassland and shrubland; and tropical evergreen broadleaf forest.

At this time we are archiving data for the following sites.

Site Site Location Biome 2000 2001 2002 2003 2004
NOBS BOREAS NSA, Canada boreal forest   X X X  
AGRO Bondville, Illinois, USA cropland (corn and soybean) X        
HARV Harvard Forest LTER, Massachusetts, USA temperate mixed forest   X X X  
KONZ Konza Prairie LTER, Kansas, USA tallgrass prairie X        
CHEQ Park Falls, Wisconsin, USA temperate mixed forest X        
METL Cascades, Oregon, USA temperate needleleaf forest     X    
SEVI Sevilleta LTER, New Mexico, USA desert     X X  
TAPA Tapajos, Brazil tropical broadleaf evergreen forest         X
TUND Barrow, AK, USA arctic tundra     X    

The NPP surfaces were produced by a spatial version of an ecosystem process model named, Biome-BGC. Inputs to the model included Landsat ETM+ derived Land Cover and LAI, tower derived meteorological variables, and a set of site-level ecophysical parameters. The model was calibrated using field measured NPP and validated by tower derived estimates of GPP.

Each BigFoot NPP product covers a 7 x 7 km extent and consists of the NPP surface in ASCII Raster (BIL - Band Interleaved by Line) format (280 rows by 280 columns at 25 meter resolution) and an accompanying text file which provides metadata specific to the image (such as projection, data type, etc).

Additional information on NPP surface development can be found on the BigFoot website at

BigFoot Project Background: Reflectance data from MODIS, the Moderate Resolution Imaging Spectrometer onboard NASA's Earth Observing System (EOS) satellite Terra (, is used to produce several science products including land cover, leaf area index (LAI), gross primary production (GPP) and net primary production (NPP). The overall goal of the BigFoot Project was to provide validation of these products. To do this, BigFoot combined ground measurements, additional high resolution remote sensing data, and ecosystem process models at nine flux tower sites representing different biomes to evaluate the effects of the spatial and temporal patterns of ecosystem characteristics on MODIS products. BigFoot characterized up to a 7 x 7 km area (49 MODIS pixels) surrounding the CO2 flux towers located at each of the nine sites. We collected multi-year, in situ measurements of ecosystem structure and functional characteristics related to the terrestrial carbon cycle. Our sampling design allowed us to examine scales and spatial pattern of these properties, the inter-annual variability and validity of MODIS products, and provided for a field-based ecological characterization of the flux tower footprint. BigFoot was funded by NASA's Terrestrial Ecology Program.

For more details on the BigFoot Project, please visit the website:

Additionally, a set of NPP/GPP summary figures was developed for each of the nine BigFoot sites. Each set contains images and figures associated with creating the BigFoot NPP and GPP products, comparing them to MODIS products, and assessing the causes of differences. Check the GPP/NPP Site Summaries description and index.

Data Citation:

Cite this data set as follows:

Turner, D. P., W. D. Ritts, and M. Gregory. 2006. BigFoot NPP Surfaces for North and South American Sites, 2000-2004. Data set. Available on-line [] from Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, U.S.A. doi:10.3334/ORNLDAAC/750.


Turner, D. P., W. D. Ritts, W. B. Cohen, S. T. Gower, M. Zhao, S. W. Running, S. C. Wofsy, S. Urbanski, A. Dunn, and J. W. Munger. 2003. Scaling gross primary production (GPP) over boreal and deciduous forest landscapes in support of MODIS GPP product validation. Remote Sensing of Environment 88:256-270.

Turner, D. P., W. D. Ritts, W. B. Cohen, T. K. Maeirsperger, S. T. Gower, A. A. Kirschbaum, S. W. Running, M. Zhao, S. C. Wofsy, A.L. Dunn, B. E. Law, J. C. Campbell, W. C. Oechel, H. J. Kwon, T. P. Meyers, E. E. Small, S. A. Kurc, and J. A. Gamon. 2005. Site-level evaluation of satellite-based global terrestrial GPP and NPP monitoring. Global Change Biology 11:666-684.

Turner, D. P., W. D. Ritts, W. B. Cohen, S. T. Gower, S. W. Running, M. Zhao, M. Costa, A. Kirschbaum, J. Ham, S. Saleska, D. E. Ahl. In Press. Evaluation of MODIS NPP and GPP Products Across Multiple Biomes. Global Change Biology.

Turner, D. P., W. D. Ritts, M. Zhao, S. A. Kurc, A. L. Dunn, S. C. Wofsy, E. E. Small, S. W. Running. In Press. Assessing interannual variation in MODIS-based estimates of gross primary production. IEEE Transactions in Geosciences and Remote Sensing.

Data Format:

Each BigFoot NPP product covers a 7 x 7 km extent and consists of the NPP surface in ASCII Raster (BIL - Band Interleaved by Line) format, with 280 rows by 280 columns at 25 meter resolution. An accompanying text file provides metadata specific to the image (such as projection, data type, etc.) and examples for loading the files into GIS software.

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