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VEMAP 2: ANNUAL ECOSYSTEM MODEL RESPONSES TO U.S. CLIMATE CHANGE, 1994-2100
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Summary:

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).

Data Citation:

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.

References:

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.

Data Format:

The model output data files are stored and distributed in netCDF format.

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.

VEMAP Grid Characteristics

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

Available VEMAP 2 Results Variables: Annual

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

VEMAP 2 Results - Variable Naming Conventions and Description

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 -

VEMAP 2 Results - File Naming Conventions and Description

Variable name

Model

GCM model

GCM experi-
ment

CO2
experi-
ment

Veg-
etation

Time step

Release

Grid

Compression

# characters

4

4

2

2

1

1

1

4

1

3

Range of possible

values

model

dependent

TEMx
BBGC
LPJx
CENT
GTEC
MC1x

C1
H2

Su
xx

C
x

V

A
M
D

model

dependent

i

-
*.gz

example #1: aetxLPJxC1SuCVA4020i.nc.gz

variable = aetx (total actual evaporation)
model = LPJx (Lund/Pik/Jena)
GCM model = C1  (CGCM1)
GCM experiment = Su (sulphate aerosols)
CO2 experiment = C (increasing CO2)
vegetation = V (VEMAP vveg2)
time step = A (annual)
release = 4020
grid representation = i (inflated)
compression = .gz (gzipped)

example #2: laiwMC1xH2SuxVA3010i.nc

variable = laiw (woody LAI)
model = MC1x (Oregon State Univ; USDA Forest Service-MAPSS Team)
GCM model = H2  (Hadley HADCM2)
GCM experiment = Su (sulphate aerosols)
CO2 experiment = x (constant CO2)
vegetation = V (VEMAP vveg2)
time step = A (annual)
release = 3010
grid representation = i (inflated)
compression = - (uncompressed)

Document Information:

Document Review Date:

2004/11/29