The Vegetation-Ecosystem Modeling and Analysis Project (VEMAP) was a large, collaborative, multi-institutional, international effort whose goal was to evaluate the sensitivity of terrestrial ecosystem and vegetation processes to altered climate forcing and elevated atmospheric CO2. Phase 1 of the VEMAP project developed historical (1895-1993) data sets of observed climate, soils, and vegetation compatible with the requirements of ecosystem models and vegetation distribution models. See the VEMAP Phase 1 User's Guide for more information.
Phase 2 developed historical (1895-1993) gridded data sets of climate (temperature, precipitation, solar radiation, humidity, and wind speed) and projected (1994-2100) gridded annual and monthly climate data sets using output from two climate system models (CCCma (Canadian Centre for Climate Modeling and Analysis) and Hadley Centre models). See the VEMAP Phase 2 User's Guide for additional background information.
Two Phase 2 model experiments were run. First, a set of selected biogeochemical models and coupled biogeochemical-biogeographical models were run from 1895 to 1993 to compare model responses to the historical time series and current ecosystem biogeochemistry. Second, these same models were run on the projected 1994 to 2100 data to compare their ecological responses to transient scenarios of climate and atmospheric CO2 change. Model runs were performed for daily, monthly, and annual gridded data sets. The output of the annual model runs in VEMAP grid format are contained in this data set.
The models investigated included five biogeochemical cycling models, which simulate plant production and nutrient cycles but rely on a static land-cover type, and two dynamic global vegetation models (DGVMs), which combine biogeochemical cycling processes with dynamic biogeographical processes including succession and fire simulation.
Biogeochemical Cycling Models
- Biome-BGC (BioGeochemical Cycles)
- Century
- Century rxveg
- GTEC (Global Terrestrial Ecosystem Carbon Model)
- TEM (Terrestrial Ecosystem Model)
Dynamic Global Vegetation Models
- LPJ (Lund-Potsdam-Jena
- MC1 (MC 5 modified Century)
VEMAP 2 model intercomparison results have been published by Schimel et al.(2000), Bachelet et al. (2003) and Gordon and Famiglietti (2004).
Cite this data set as follows:
Kittel, T.G.F., N.A. Rosenbloom, C. Kaufman, J.A. Royle, C. Daly, H.H. Fisher, W.P. Gibson, S. Aulenbach, D.N. Yates, R. McKeown, D.S. Schimel, and VEMAP 2 Participants. 2005. VEMAP 2: Annual Ecosystem Model Responses to U.S. Climate Change, 1994-2100. ORNL DAAC, Oak Ridge, Tennessee, USA. http://dx.doi.org/10.3334/ORNLDAAC/766.
Gordon, W. S., and J. S. Famiglietti (2004), Response of the water balance to climate change in the United States over the 20th and 21st centuries: Results from the VEMAP Phase 2 model intercomparisons, Global Biogeochem. Cycles, 18, GB1030, doi:10.1029/2003GB002098.
Bachelet, D; Neilson, RP; Hickler, T; Drapek, RJ; Lenihan, JM; Sykes, MT; Smith, B; Sitch, S; and Thonicke, K. 2003. Simulating past and future dynamics of natural ecosystems in the United States. Global Biogeochem. Cycles, 17 (2): 1045-1045.
Kittel, T. G. F., J. A. Royle, C. Daly, N. A. Rosenbloom, W. P. Gibson, H. H. Fisher, D. S. Schimel, L. M. Berliner, and VEMAP 2 Participants. 1997. A gridded historical (1895-1993) bioclimate dataset for the conterminous United States. Pages 219-222, in: Proceedings of the 10th Conference on Applied Climatology, 20-24 October 1997, Reno, NV. American Meteorological Society, Boston.
VEMAP Members. 1995. Vegetation/Ecosystem Modeling and Analysis Project (VEMAP): Comparing biogeography and biogeochemistry models in a continental-scale study of terrestrial ecosystem responses to climate change and CO2 doubling. Global Biogeochemical Cycles 9:407-437.
Schimel, D.S., Jerry Melillo, Hanqin Tian, A. David McGuire, David Kicklighter, Timothy Kittel, Nan Rosenbloom, Steven Running, Peter Thornton, Dennis Ojima, William Parton, Robin Kelly, Martin Sykes, Ron Neilson, and Brian Rizzo. 2000. Contribution of Increasing CO2 and Climate to Carbon Storage by Ecosystems in the United States. Science 17 March 2000; 287: 2004-200.
The network Common Data Form, or netCDF, refers to a comprehensive interface, library and file format designed to create, access and share scientific data. It was developed by the Unidata Program Center in Boulder, Colorado.
The grid used for the VEMAP coverage is a 0.5-deg. latitude x 0.5-deg. longitude grid covering the conterminous U.S. Grid edges are aligned with 1.0-deg. and 0.5-deg. latitude-longitude lines; grid centers are located at 0.25-deg. and 0.75-deg. latitude-longitude intersections. Latitude and longitude for each cell are included in the VEMAP data set.
The grid's minimum bounding rectangle (MBR) is defined by grid domain corners. The full 0.5deg. VEMAP grid contains 5520 cells, with 115 columns and 48 rows. Within the grid, 3261 cells are within the boundaries of the conterminous U.S. and predominantly covered by land. Background cells (ocean and inland water cells) are assigned the value of -9999. The VEMAP 'mask', found in the header of each netCDF file, enumerates land cells from 1 to 3261; background cells are indicated by 0.
VEMAP grid corners defining the minimum bounding rectangle (MBR).
Grid Position Longitude* Latitude Lower Left Corner -124.5deg. 25.0deg. Upper Right Corner -67.0deg. 49.0deg. *Negative longitudes are degrees West.
Gridded Data Files
Layout of the VEMAP gridded array, with grid cell ID numbers. Column 1 - to - 115
Row 1 1 2 3 4 ...115
116 117 118 119 ...230
231...
-to-
... Row 48 ... 5520
| Model | BBGC | CENT | CENTrx | GTEC | LPJ | MC1 | TEM |
| Time | annual | annual | annual | annual | annual | annual | annual |
| Variables | aetx ltfc nbpx neex nepx nmin nppx resh roff solc totc tslc vegc | aetx agvc laix litt nbpx nepx nmin nppx petx resh roff solc totc tslc vegc | aetx agvc laix litt nbpx nepx nmin nppx petx resh roff solc totc tslc vegc | aetx gppx nppx roff totc tslc vegc | aetx arbu bibu laiw nbpx nepx nppx roff solc totc tslc vegc vegt(vgat) | aetx agvg(vgat) arbu bibu laiw ltfc nbpx nepx nmin nppx resh roff totc tslc vegc vveg(vgvt) | aetx gppx ltfc nbpx nepx nmin nppx petx resh roff totc tslc tsln vegc vegn |
| Total | 13 | 15 | 15 | 7 | 13 | 16 | 15 |
| Variable | Description | Units: annual [yr-1] monthly [mo-1] daily [day-1] |
| aetx | total actual evapotranspiration | mm |
| agvc | Above ground live Carbon | gC |
| arbu | fraction of the gridcell that is burnt | - |
| bibu | biomass burnt | gC m-2 |
| gppx | gross primary production | gC m-2 |
| laiw | woody LAI | - |
| laix | leaf area index | - |
| litt | total fine litter | gC m-2 |
| ltfc | total litterfall carbon | gC m-2 |
| nbpx | change in total carbon | gC m-2 |
| neex | total net ecosystem exchange | gC m-2 |
| nepx | Net Ecosystem Production (NEP=NPP-RH) | gC m-2 |
| nmin | total net nitrogen mineralization | g N m-2 |
| nppx | total net primary production | g C m-2 |
| petx | potential evapotranspiration | cm |
| resh | total heterotrophic respiration | gC m-2 |
| roff | total runoff | mm H2O |
| solc | average soil organic matter carbon | gC m-2 |
| totc | mean total carbon storage | g C m-2 |
| tslc | average non-vegetation carbon | gC m-2 |
| tsln | total soil nitrogen | gN m-2 |
| vegc | mean total vegetation carbon | g C m-2 |
| vegn | vegetation nitrogen | gN m-2 |
| vegt/vgat/agvg | VEMAP aggregated vegetation classification | - |
| vveg(vgvt) | VEMAP vegetation classification | - |
Variable name | Model | GCM model | GCM experi- | CO2 | Veg- | Time step | Release | Grid | Compression | |
# characters | 4 | 4 | 2 | 2 | 1 | 1 | 1 | 4 | 1 | 3 |
Range of possible values | TEMx | C1 | Su | C | V | A | i | - |
example #1: aetxLPJxC1SuCVA4020i.nc.gz
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| example #2: laiwMC1xH2SuxVA3010i.nc
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2004/11/29