VEMAP Phase I - Objectives and Experimental Design

The Vegetation/Ecosystem Modeling and Analysis Project, VEMAP, is a multi-institutional, international effort whose goal is to evaluate the sensitivity of terrestrial ecosystem and vegetation processes to altered climate forcing and elevated atmospheric CO2.

The project's objectives are:

CGD's Ecosystem Dynamics and the Atmosphere Section participation in VEMAP included the development of a common model input database (VEMAP Data Project). Complete documentation for the VEMAP database is available in the "User's Guide to the VEMAP Phase I Database".


VEMAP is currently in the second phase of model intercomparison and analysis. The objectives of this phase are to compare time-dependant ecological responses of biogeochemical and coupled biogeochemical-biogeographical models to historical and projected transient forcings across the conterminous U.S. These model experiments will be driven by historical time series and projected transient scenarios of climate, atmospheric CO2, and N-deposition.

National/International Program Sponsorship

VEMAP is supported by Electric Power Research Institute (EPRI) , NASA's Mission to Planet Earth (MTPE) , and USDA Forest Service Southern Global Change Program. Development of the VEMAP database was additionally supported by the National Science Foundation's Climate Dynamics Program through the University Corporation for Atmospheric Research's Climate System Modeling Program.

The VEMAP project is involved with several large U.S. and international scientific programs. These include NASA's Earth Observing System (EOS) Program, which supports several of the modeling groups. Within the International Geosphere/Biosphere Program (IGBP), VEMAP is a designated activity of the Global Change and Terrestrial Ecosystems (GCTE) Core Project.

The VEMAP Dataset

Phase I of the VEMAP project developed a model database of climate, soils, and vegetation compatible with the requirements of three ecosystem physiology models and three vegetation lifeform distribution models. A key constraint was temporal, spatial, and physical consistency among data layers to provide these daily or monthly timestep models with suitable common inputs for the purpose of model intercomparison. The database is on a 0.5 degree latitude/longitude grid for the conterminous United States.

The set has both daily and monthly representations of the same long-term climate. Daily temperatures and precipitation were stochastically simulated with WGEN and daily solar radiation and humidity empirically estimated with CLIMSIM. We used orographically-adjusted precipitation, surface temperature, and surface wind speed monthly means to maintain consistency among these fields and with vegetation distribution. Vegetation classes were based on physiognomic and physiological properties that influence biogeochemical dynamics. Soils data include characteristics of the 1 -4 dominant soils per cell to account for subgrid variability. We derived climate change scenarios from the output of seven general circulation models (GCM's) and one nested regional climate model.

The VEMAP database is available through this webpage or directly via FTP. The data are presented in two forms:

  1. Gridded format suitable for import directly into GIS systems
  2. A cell location/time series listing of each variable for rapid access to specific locations for site level studies.
Access to the VEMAP Dataset

VEMAP Mailing List

If you would like to receive updates to the VEMAP database, you may subscribe to the vemap users mailing list.

VEMAP Participants and Sponsors

Participating Models


VEMAP Phase I Results

Results from Phase I of the VEMAP project are summarized in the VEMAP Members (1995) paper. Output files from the VEMAP Phase I model runs are available on the UCAR anonymous FTP site.

Data Analysis and Validation - Integrated NDVI (iNDVI)

VEMAP References


Revised 09-07-2000 Contacts