This data set provides standardized output variables for gross primary productivity (GPP), net ecosystem exchange (NEE), leaf area index (LAI), ecosystem respiration (Re), latent heat flux (LE), and sensible heat flux (H) from 24 terrestrial biosphere models for 47 eddy covariance flux tower sites in North America. Each model used standardized input data for each flux tower site (i.e., gap-filled, locally observed weather; land use history; and other site specific data) and followed standard model setup and spinup procedures. The files also contain gap-filled observations and total uncertainty estimates. The data set was compiled for the North American Carbon Program (NACP) Site-Level Synthesis for use in model inter-comparison and assessment of how well the models simulate carbon processes across vegetation types and environmental conditions in North America.
There is one compressed (.zip) file with this data set. When expanded, the .zip file contains model output data for one variable at one site. The model output and observations are available at the native half-hourly time step, or in daily, monthly, and annual aggregations, in comma-separated text (.csv) format.
Figure 1. Example of plots displaying the diurnal growing season averages for the six output variables for each of the 47 modeled sites. Plots are included as companion files. This plot shows the modeled output for the diurnal cycle of growing season (defined as June, July and August) net ecosystem exchange (NEE) at the Lethbridge grassland site in Alberta, Canada. Plotted values are the outputs from the 11 models that submitted hourly or finer temporal resolution data for the site. Also shown are the ensemble mean of these 11 models (thick red line) and the gap-filled observations from the eddy covariance site (thick black line). The legend includes an entry for each of the 15 participating models; however, 4 models that did not submit results for this site are not represented on the plot. Models that reported a coarser temporal resolution (e.g. daily or monthly) are not included in either the legend or the plot.
Figure 2. Example of plots displaying the annual seasonal averages for the six output variables for each of the 47 modeled sites. Plots are included as companion files. This plot shows the modeled output for the seasonal cycle of net ecosystem exchange (NEE) at the Lethbridge grassland site in Alberta, Canada. In the top panel, 11 models with hourly or finer temporal resolution are plotted along with the ensemble mean of all 15 models that submitted results for this site (thick red line) and the gap-filled observations from the eddy covariance site (thick black line). The legend includes an entry for each participating model that submitted hourly or finer temporal resolution; however, 4 models that did not submit results for this site are not represented on the plot. In the bottom panel, 5 models with daily or coarser temporal resolution are shown along with the ensemble mean of all 15 models (thick red line) and the gap-filled observations from the eddy covariance site (thick black line). The legend includes an entry for each participating model that submitted daily or coarser temporal resolution; however, 3 models that did not submit results for this site are not represented on the plot.
Data and Documentation Access:
Links to Related Data Products:
NACP Site: Tower Meteorology, Flux Observations with Uncertainty, and Ancillary Data [http:daac.ornl.gov/cgi-bin/dsviewer.pl?ds_id=1178]
NACP Site: Terrestrial Biosphere Model Output Data in Original Format
The Protocol for the NACP Site-level Interim Synthesis Model-Data Comparison (Site Synthesis), Version 7, is included as a companion file. See Site_Synthesis_Protocol_v7.pdf.
Plots displaying the diurnal growing season and annual seasonal averages for the six output variables for each of the 47 modeled sites are included as companion files. The captions for Figures 1 and 2 describe the plotted data and legends. See the companion file, figures.zip.
Cite this data set as follows:
Ricciuto, D.M., K. Schaefer, P.E. Thornton, K. Davis, R.B. Cook, Shishi Liu, R. Anderson, M.A. Arain, I. Baker, J.M. Chen, M. Dietze, R. Grant, C. Izaurralde, A.K. Jain, A.W. King, C. Kucharik, Shuguang Liu, E. Lokupitiya, Y. Luo, C. Peng, B. Poulter, D. Price, W. Riley, A. Sahoo, H. Tian, C. Tonitto, and H. Verbeeck. 2013. NACP Site: Terrestrial Biosphere Model and Aggregated Flux Data in Standard Format. Data set. Available on-line [http://daac.ornl.gov] from Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, USA. http://dx.doi.org/10.3334/ORNLDAAC/1183
Project: North American Carbon Project (NACP)
The North American Carbon Program (NACP) (Denning et al., 2005; Wofsy and Harriss, 2002) is a multidisciplinary research program to obtain scientific understanding of North America's carbon sources and sinks and of changes in carbon stocks needed to meet societal concerns and to provide tools for decision makers. Successful execution of the NACP has required an unprecedented level of coordination among observational, experimental, and modeling efforts regarding terrestrial, oceanic, atmospheric, and human components. The project has relied upon a rich and diverse array of existing observational networks, monitoring sites, and experimental field studies in North America and its adjacent oceans. It is supported by a number of different federal agencies through a variety of intramural and extramural funding mechanisms and award instruments.
MAST-DC organized several synthesis activities to evaluate and inter-compare biosphere model outputs and observation data at local to continental scales for the time period of 2000 through 2005. The synthesis activities have included three component studies, each conducted on different spatial scales and producing numerous data products: (1) site-level synthesis that examined process-based model estimates and observations at over 30 AmeriFlux and Fluxnet-Canada tower sites across North America; (2) a regional, mid-continent intensive study centered in the agricultural regions of the United States and focused on comparing inventory-based estimates of net carbon exchange with those from atmospheric inversions; and (3) a regional and continental synthesis evaluating model estimates against each other and available inventory-based estimates across North America. A number of other NACP syntheses are underway, including ones focusing on non-CO2 greenhouse gases, the impact of disturbance on carbon exchange, and coastal carbon dynamics. The Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC) is the archive for the NACP synthesis data products.
NACP Site Synthesis
This data set is part of the NACP Site Synthesis which is divided into three separate data components: model driver data and observations (Data Set 1), the processed model output (Data Set 2), and the original model output (Data Set 3).
This data set (Data Set 2) provides the processed outputs of 24 terrestrial biosphere models (Schwalm et al., 2010) for model inter-comparison and assessment of how well the models simulate carbon process across vegetation types and environmental conditions at 47 eddy covariance flux tower sites in North America. Standardized files have been generated from the models for the following output variables: gross primary productivity (GPP), net ecosystem exchange (NEE), leaf area index (LAI), ecosystem respiration (Re), latent heat flux (LE), and sensible heat flux (H). Each file contains output from the models for one variable at one site. These files also contain gap-filled observations and total uncertainty estimates from Barr et al. (2009; 2013b) and Schaefer et al. (2012). The data files are available at the native half-hourly time step, or in daily, monthly, and annual averages. The files are in ASCII format.
|Contact||Model||Model Short Name|
|Dan M. Ricciutoemail@example.com|
|Kevin Schaefer||combined Simple Biosphere-Carnegie_Ames_Stanford_Approach (SiBCASA) Model||SiBCASAfirstname.lastname@example.org|
|Peter E. Thorntonemail@example.com|
|Robert B. Cookfirstname.lastname@example.org|
|Ryan Anderson||BIOME_BGC (BioGeochemical Cycles)||BIOME-BGCemail@example.com|
|M. Altaf Arain||Carbon and Nitrogen (CN) Canadian Land Surface Scheme (CLASS)||CN-CLASSfirstname.lastname@example.org|
|Ian Baker||Simple Biosphere model v 3||SiB3email@example.com|
|Jing Ming Chen||Boreal Ecosystems Productivity Simulator||BEPSfirstname.lastname@example.org|
|Michael Dietze||Ecosystem Demography Model v 2||ED2email@example.com|
|Robert Grant||Ecosys terrestrial ecosystem model||ecosys||Robert.Grant@afhe.ualberta.ca|
|Cesar Izaurralde||Erosion-Productivity Impact Calculator (EPIC) model||EPIC||cesar.Izaurralde@pnl.gov|
|Atul K. Jain||Integrated Science Assessment Model||ISAMfirstname.lastname@example.org|
|Anthony W. King||Local Terrestrial Ecosystem Carbon (LoTEC) model - Data Assimilation (DA) mode||LoTEC_DAemail@example.com|
|Chris Kucharik||Agro-Integrated BIosphere Simulator||Agro-IBISfirstname.lastname@example.org|
|Shuguang Liu||Eddy Covariance (EC)-Light Use Efficiency (LUE) Erosion–Deposition-Carbon-Model (EDCM)||ECLUEEDCMemail@example.com|
|Erandi Lokupitiya||coupled Simple Biosphere (SiB) - crop phenology model (SiBcrop)||SiBcropfirstname.lastname@example.org|
|Yiqi Luo||Terrestrial ECOsystem (TECO) model||TECOemail@example.com|
|Changhui Peng||TRIPLEX generic hybrid model of forest growth and carbon and nitrogen dynamics||CLASS-CTEM (TRIPLEX-Flux)||firstname.lastname@example.org|
|Ben Poulter||Lund-Potsdam-Jena Dynamic Global Vegetation Model, Swiss Federal Research Institute WSL modification||LPJemail@example.com|
|David Price||Canadian Integrated BIosphere Simulator||Can-IBIS||David.Price@NRCan-RNCan.gc.ca|
|William Riley||Isotope Land Surface Model||ISOLSMfirstname.lastname@example.org|
|Alok Sahoo||Simplified Simple Biosphere (SSiB) model||SSIB2email@example.com|
|Hanqin Tian||Dynamic Land Ecosystem Model||DLEMfirstname.lastname@example.org|
|Christina Tonitto||Denitrification-Decomposition (DNDC) biogeochemical model||DNDCemail@example.com|
|Hans Verbeeck||Organizing Carbon and Hydrology in Dynamic Ecosystems||ORCHIDEE||Hans.Verbeeck@UGent.be|
Note: See Table 2 in Schaefer et al. (2012) for a summary of model characteristics and references.
This data set contains standardized, processed output from 24 terrestrial biosphere models for 47 flux tower sites in North America. The output variables are: gross primary productivity (GPP), net ecosystem exchange (NEE), leaf area index (LAI), ecosystem respiration (Re), latent heat flux (LE), and sensible heat flux (H). The data files also contain gap-filled observations and total uncertainty estimates from Barr et al. (2009) and Schaefer et al. (2012). Data are provided at the native half-hourly time step, daily, monthly, and annual averages. The data files are in comma-separated text (.csv) format.
2.1. Spatial Coverage
Site: North America
Site boundaries: (All latitude and longitude given in decimal degrees)
|Site (Region)||Westernmost Longitude||Easternmost Longitude||Northernmost Latitude||Southernmost Latitude|
2.2. Spatial Resolution
Point (lat/lon) centered around flux tower
2.3. Temporal Coverage
2.4. Temporal Resolution
Half-hourly, daily, monthly, and annual aggregations
2.5. Time Variable
Standardized files are in local standard time (LST) with the timestamp representing the beginning of the averaging period. To match this standard, model output has been time-shifted when necessary
2.6. Data File Information
Table 1. Data Files
|FILE AND FOLDER NAMES|
|COMPRESSED FILE NAME||FILE FOLDER NAMES||DATA FILE FOLDER NAMES FOR EACH SITE||DATA FILES FOR EACH SITE|
Note: * represents the 6-character tower codes used in the site lists (see Tables 3 and 4).
2.7. Companion File Information
Table 2. Companion Files
|NACP_uncertainty_analysis.pdf||Methodology of estimating uncertainty|
|Richardson_gap_filling_2009.pdf||Explanation of algorithmic uncertainties in GPP/RE partitioning and gap filling of NEE, at annual and half-hourly time scales|
|site_information_basic.csv||Basic information about each flux tower site (site code, name, PI, affiliation, email, address, references, priority, biome, etc.)|
|site_information_extended.pdf||Summarizes site code, name, PI, affiliation, email, address, references, priority, biome, etc.|
|site_location_summary.csv||Summarizes all site location information required as input to all models: latitude, longitude, elevation, instrument height, biome, start and stop years, time zone shift to local standard time, and the flux time averaging period|
|site_synthesis_protocol_v7.pdf||Describes standardized site synthesis protocol|
|figures.zip||Plots representing diurnal and seasonal averages for the six output variables for each of the 47 modeled sites.|
|figures_readme.pdf||Examples of plots from figures.zip with plot and legend descriptions. The examples provided are Figures 1 and 2 in this document.|
This data product contributes to a multidisciplinary research program to obtain scientific understanding of North America's carbon sources and sinks and of changes in carbon stocks needed to meet societal concerns and to provide tools for decision makers. The data were generated as part of a NACP site-level synthesis to evaluate and inter-compare models and observation measurements across North America.
This data set contains standardized, processed outputs of 24 terrestrial biosphere models and was used to inter-compare model simulations and assess how well terrestrial biosphere models simulate carbon processes across vegetation types and environmental conditions at 47 eddy covariance flux tower sites in North America.
The modeling teams used standard model input data derived from local observations, simulation setup procedures, model outputs, and analysis techniques to ensure a valid and fair comparison of model results against observations. Using standardized input, output, and analysis techniques also minimized setup and analysis time and allowed investigators to accurately gauge model and data uncertainty with minimal error and bias.
Overall, there was a very large spread in model performance. See discussions on model inter-comparisons and model-data comparisons in Dietze et al. (2011), Richardson et al. (2012), Schaefer et al. (2012), and Schwalm et al. (2010).
Figure 3. GPP Annual Bias, as shown in this light use efficiency (LUE) curve for the US-Me2 Flux Tower Site (Schaefer et al., 2012). The slope of the LUE curve drives the annual bias.
5.1 Participating Flux Tower Sites
Participating eddy flux covariance towers in the Site Synthesis were divided into a Priority 1 and a Priority 2 list. The Priority 1 sites represent a broad range of vegetation types and geographic regions to test each model’s performance under the fullest range of expected conditions across North America. No more than three Priority 1 sites were chosen to represent each of the major biome types in North America as defined by the IGBP biome classification.
The Priority 1 list represents the minimum number of tower sites required to evaluate model performance in North America. The Priority 2 list expands the site selection to include towers required for specialized analyses. Each participating site provided data as input to models and for comparison with model output, as described below.
An additional 11 flux tower sites that lacked ancillary and biological data were identified as third-priority sites (see Figure 4) but were not used as part of the model-data comparison.
For each site we used the unique FLUXNET code CC-XXX, where CC is a two letter country code and XXX is a three letter site code. The site codes are a unique identifier for each site and a convenient naming convention for all model input and output files.
Figure 4. Flux Tower Site Locations: First-priority sites (36 sites) and Second-priority sites (11 chronosequence sites) were used for the model-data comparison. The third-priority sites (11 sites) were not used as part of the model-data comparison.
Table 3. NACP Site-Level Synthesis - First-priority sites (36 sites). These sites have forcing and flux with uncertainty data but not all sites provided ancillary data.
|FLUXNET Site Code||Full Name||Period of Record1||Flux w/ Uncertainty Data||Ancillary Data||State/Prov||Type2|
|US-ARM||ARM – Southern Great Plains||2000-2006||yes||yes||OK||CRO|
|US-Ne1||Mead – Irrigated maize||2001-2006||yes||yes||NE||CRO|
|US-Ne2||Mead – Irrigated maize/soybean||2001-2006||yes||yes||NE||CRO|
|US-Ne3||Mead – Rainfed maize/soybean||2001-2006||yes||yes||NE||CRO|
|US-IB1||Fermi Lab – Maize/soybean rotation||2005-2007||yes||yes||IL||CRO|
|US-IB2||Fermi Lab – Prairie||2004-2007||yes||yes||IL||GRA|
|CA-Oas||BERMS – Old Aspen||1997-2006||yes||yes||SK||DBF|
|US-Ha1||Harvard Forest – EMS Tower||1991-2006||yes||yes||MA||DBF|
|US-Dk2||Duke Forest – Hardwood||2003-2005||yes||yes||NC||DBF|
|US-UMB||University of Michigan Biological Station (UMBS)||1998-2006||yes||yes||MI||DBF|
|US-MMS||Morgan Monroe State Forest||1999-2006||yes||yes||IN||DBF|
|CA-Man||BOREAS – Northern Study Area, Old Black Spruce||1994-2006||yes||yes||MB||ENFB|
|CA-Obs||BERMS – Old Black Spruce||2000-2006||yes||yes||SK||ENFB|
|CA-Ojp||BERMS – Old Jack Pine||2000-2006||yes||yes||SK||ENFB|
|CA-Qfo||Quebec – Mature Black Spruce||2004-2006||yes||yes||QB||ENFB|
|CA-Ca1||Campbell River – Mature Douglas-fir||1998-2006||yes||yes||BC||ENFT|
|US-Dk3||Duke Forest – Loblolly Pine||1998-2005||yes||yes||NC||ENFT|
|US-Ho1||Howland Forest – Main Tower||1996-2004||yes||yes||ME||ENFT|
|US-Me2||Metolius – Intermediate-aged Ponderosa Pine||2002-2007||yes||yes||OR||ENFT|
|CA-TP4||Turkey Point – Mature||2002-2007||yes||yes||ON||ENFT|
|US-PFa||Park Falls / WLEF||1997-2005||yes||yes||WI||MF|
|US-Syv||Sylvania Wilderness Area||2001-2006||yes||yes||MI||MF|
|CA-Gro||Groundhog River Station||2004-2006||yes||yes||ON||MF|
|US-SO2||Sky Oaks – Old||1998-2006||yes||yes||CA||SHR|
|CA-Mer||Eastern Peatland – Mer Bleue||1999-2006||yes||yes||ON||WET|
|CA-WP1||Western Peatland – LaBiche River||2003-2007||yes||no||AB||WET|
Table 4. NACP Site-Level Synthesis - Second-priority sites (11 chronosequence sites). All second-priority sites have forcing data but not all sites have flux with uncertainty data and none provided ancillary data.
|FLUXNET Site Code||Full Name||Period of Record1||Flux w/ Uncertainty Data||Ancillary Data||State/Prov||Type2|
|CA-SJ1||BERMS – Jack Pine, 1994 harvest||2002-2005||yes||no||SK||ENFB|
|CA-SJ2||BERMS – Jack Pine, 2002 harvest||2003-2006||yes||no||SK||ENFB|
|CA_SJ3||BERMS – Jack Pine, 1975 harvest||2004-2005||yes||no||SK||ENFB|
|CA-Ca2||Campbell River – Douglas-fir clearcut||2001-2006||yes||no||BC||ENFT|
|CA-Ca3||Campbell River – Douglas-fir juvenile||2002-2006||yes||no||BC||ENFT|
|US-Me3||Metolius – Ponderosa Pine, young #2||2004-2005||yes||no||OR||ENFT|
|US-Me4||Metolius – Ponderosa Pine, old-growth||1996-2000||no||no||OR||ENFT|
|US-Me5||Metolius – Ponderosa Pine, Young #1||1999-2002||yes||no||OR||ENFT|
|CA-TP1||Turkey Point – Young||2003-2007||no||no||ON||ENFT|
|CA-TP2||Turkey Point – Seedling||2003-2007||no||no||ON||ENFT|
|CA-TP3||Turkey Point – Middle-aged||2003-2007||no||no||ON||ENFT|
Notes (apply to both tables):
1Start-end years in the gap-filled weather data. Partial years (from flux data record) have been extended to complete years of surface weather data to simplify model forcing. 2Types were assigned for convenience in this project, to identify combination of vegetation type and climate zone as an aid in site selection. These type names are not intended to match the IGBP classification assigned in other databases. Class: CRO = crop; GRA = grassland; ENFB = evergreen needleleaf forest – boreal; ENFT = evergreen needle leaf forest – temperate; DBF = deciduous broadleaf forest; MF = mixed (deciduous/evergreen) forest; WSA = woody savanna; SHR = shrubland; TUN = tundra; and WET = wetland. An additional 11 flux tower sites, which lack ancillary and biological data templates, were identified as third-priority sites (see Figure 4) but were not used as part of the model-data comparison.
5.2 Site Synthesis Protocol
Participating modeling teams followed the NACP Site Synthesis Protocol (Site_Synthesis_Protocol_v7.pdf) which covers procedures, plans, and infrastructure for the site-level analyses. MAST-DC provided each modeling team with standardized model input data for each flux tower site. The input data included: gap-filled, locally observed weather; remotely-sensed phenology; land use history; and site description data. The input data are described and provided in a related data set, NACP Site: Tower Meteorology, Flux Observations with Uncertainty, and Ancillary Data (10.3334/ORNLDAAC/1178). To ensure consistency, each modeling team followed standard model setup and spinup procedures (see the NACP Site Synthesis Protocol). All models used their standard values for various biophysical parameters except LoTEC, which used optimized parameter values obtained through data assimilation (Ricciuto et al., 2011).
5.3 Model Output
Included here is the latest version of processed model output (mid-December 2009). GPP, NEE, and Re files have been further updated in November 2012 to provide total uncertainty estimated by Schaefer et al. (2012). However, LE and H have not been updated, and only contain the random and u* threshold uncertainty summed in quadrature. Plots representing diurnal and seasonal averages for these output variables are also provided in the companion file figures.zip.
This data set is available through the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).
Contact for Data Center Access Information:
Telephone: +1 (865) 241-3952
Barr, A.G., D.M. Ricciuto, K. Schaefer, A. Richardson, D. Agarwal, P.E. Thornton, K. Davis, B. Jackson, R.B. Cook, D.Y. Hollinger, C. van Ingen, B. Amiro, A. Andrews, M.A. Arain, D. Baldocchi, T.A. Black, P. Bolstad, P. Curtis, A. Desai, D. Dragoni, L. Flanagan, L. Gu, G. Katul, B.E. Law, P. Lafleur, H. Margolis, R. Matamala, T. Meyers, H. McCaughey, R. Monson, J.W. Munger, W. Oechel, R. Oren, N. Roulet, M. Torn, and S. Verma. 2013. NACP Site: Tower Meteorology, Flux Observations with Uncertainty, and Ancillary Data. Data set. Available on-line [http://daac.ornl.gov] from Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, USA http://dx.doi.org/10.3334/ORNLDAAC/1178
Barr, A.G., A.D. Richardson, D.Y. Hollinger, D. Papale, M.A. Arain, T.A. Black, G. Bohrer, D. Dragoni, M.L. Fischer, L. Gu, B.E. Law, H.A. Margolis, J.H. McCaughey, J.W. Munger, W. Oechel, K. Schaeffer. 2013b. Use of change-point detection for friction–velocity threshold evaluation in eddy-covariance studies. Agricultural and Forest Meteorology, 171–172: 31-45 http://dx.doi.org/10.1016/j.agrformet.2012.11.023
Barr, A.G., D. Hollinger, and A. D. Richardson. 2009. CO2 flux measurement uncertainty estimates for NACP. Eos Transactions SGU, 90(52), Fall Meeting, Abstract B54A-04.
Denning, A.S., et al. 2005. Science implementation strategy for the North American Carbon Program: A Report of the NACP Implementation Strategy Group of the U.S. Carbon Cycle Interagency Working Group. U.S. Carbon Cycle Science Program, Washington, DC. 68 pp.
Dietze, M.C., R. Vargas, A.D. Richardson, P.C. Stoy, A.G. Barr, R.S. Anderson, M.A. Arain, I.T. Baker, T.A. Black, J.M. Chen, P. Ciais, L.B. Flanagan, C.M. Gough, R.F. Grant, D. Hollinger, C. Izaurralde, C.J. Kucharik, P. Lafleur, S. Liu, E. Lokupitiya, Y. Luo, J.W. Munger, C. Peng, B. Poulter, D.T. Price, D.M. Ricciuto, W.J. Riley, A.K. Sahoo, K. Schaefer, A.E. Suyker, H. Tian, C. Tonitto, H. Verbeeck, S.B. Verma, W. Wang, and E. Weng. 2012. Characterizing the performance of ecosystem models across time scales: A spectral analysis of the North American Carbon Program site-level synthesis. Journal of Geophysical Research: Biogeosciences 116: G04029. doi:10.1029/2011JG001661
Ricciuto, D.M., A.W. King, D. Dragoni, and W.M. Post. 2011. Parameter and prediction uncertainty in an optimized terrestrial carbon cycle model: Effects of constraining variables and data record length, J. Geophys. Res. 116: G01033. doi:10.1029/2010JG001400
Richardson, A.D., R.S. Anderson, M.A. Arain, A.G. Barr, G. Bohrer, G. Chen, J.M. Chen, P. Ciais, K.J. Davis, A.R. Desai, M.C. Dietze, D. Dragoni, S.R. Garrity, C.M. Gough, R. Grant, D.Y. Hollinger, H.A. Margolis, H. McCaughey, M. Migliavacca, R.K. Monson, J.W. Munger, B. Poulter, B.M. Raczka, D.M. Ricciuto, A.K. Sahoo, K. Schaefer, H. Tian, R. Vargas, H. Verbeeck, J. Xiao, and Y. Xue. 2012. Terrestrial biosphere models need better representation of vegetation phenology: Results from the North American Carbon Program site synthesis. Global Change Biology 18(2): 566-584. doi:10.1111/j.1365-2486.2011.02562.x
Schaefer, K., C. Schwalm, C. Williams, M.A. Arain, A. Barr, J. Chen, K.J. Davis, D. Dimitrov, T.W. Hilton, D.W. Hollinger, E. Humphreys, B. Poulter, B.M. Raczka, A.D. Richardson, A. Sahoo, P.E. Thornton, R. Vargas, H. Verbeeck, R. Anderson, I. Baker, T.A. Black, P. Bolstad, Jiquan Chen, P. Curtis, A.R. Desai, M. Dietze, D. Dragoni, C. Gough, R.F. Grant, L. Gu, A. Jain, C. Kucharik, B. Law, S. Liu, E. Lokipitiya, H.A. Margolis, R. Matamala, J.H. McCaughey, R. Monson, J.W. Munger, W. Oechel, C. Peng, D.T. Price, D. Ricciuto, W.J. Riley, N. Roulet, H. Tian, C. Tonitto, M. Torn, E. Weng, X. Zhou 2012. A model-data comparison of gross primary productivity: Results from the North American Carbon Program site synthesis. Journal of Geophysical Research: Biogeosciences 117: G03010. doi:10.1029/2012JG001960
Schwalm, C., C.A. Williams, K. Schaefer, R. Anderson, M.A. Arain, I. Baker, A. Barr, T.A. Black, G. Chen, J.M. Chen, P. Ciais, K.J. Davis, A. Desai, M. Dietze, D. Dragoni, M.L. Fischer, L.B. Flanagan, R. Grant, L. Gu, D. Hollinger, R.C. Izaurralde, C. Kucharik, P. Lafleur, B.E. Law, L. Li, Z. Li, S. Liu, E. Lokupitiya, Y. Luo, S. Ma, H. Margolis, R. Matamala, H. McCaughey, R.K. Monson, W.C. Oechel, C. Peng, B. Poulter, D.T. Price, D.M. Riciutto, W. Riley, A. Kumar Sahoo, M. Sprintsin, J. Sun, H. Tian, C. Tonitto, H. Verbeeck, and S.B. Verma. 2010. A model-data intercomparison of CO2 exchange across North America: Results from the North American Carbon Program site synthesis. Journal of Geophysical Research: Biogeosciences 115: G00H05. doi:10.1029/2009jg001229
Wofsy, S.C., and R.C. Harriss. 2002. The North American Carbon Program (NACP). Report of the NACP Committee of the U.S. Interagency Carbon Cycle Science Program. U.S. Global Change Research Program, Washington, DC. 56 pp.
Additional Sources of Information:
Keenan, T.F., I. Baker, A. Barr, P. Ciais, K. Davis, M. Dietze, D. Dragoni, C.M. Gough, R. Grant, D. Hollinger, K. Hufkens, B. Poulter, H. McCaughey, B. Rackza, Y. Ryu, K. Schaefer, H. Tian, H. Verbeeck, M. Zhao, and A.D. Richardson. 2012. Terrestrial biosphere model performance for inter-annual variability of land-atmosphere CO2 exchange. Global Change Biology 18(6): 1971–1987. doi:10.1111/j.1365-2486.2012.02678.x
Li H., M. Huang, M.S. Wigmosta, Y. Ke, A.M. Coleman, L.Y.R. Leung, A. Wang, and D.M. Ricciuto. 2011. Evaluating runoff simulations from the Community Land Model 4.0 using observations from flux towers and a mountainous watershed. Journal of Geophysical Research: Atmospheres 116: D24120. doi:10.1029/2011JD016276
Sulman, B.N., A.R. Desai, N.M. Schroeder, D. Ricciuto, A. Barr, A.D. Richardson, L.B. Flanagan, P.M. Lafleur, H. Tian, G. Chen, R.F. Grant, B. Poulter, H. Verbeeck, P. Ciais, B. Ringeval, I.T. Baker, K. Schaefer, Y. Luo, and E. Weng. 2012. Impact of hydrological variations on modeling of peatland CO2 fluxes: Results from the North American Carbon Program site synthesis. Journal of Geophysical Research: Biogeosciences 117: G01031. doi:10.1029/2011JG001862