Historical VEMAP 2 netCDF Documentation VEMAP Phase 2 Transient Climate Dataset Annual and Monthly Historical Climate (1895-1993) 1 March 2001 NCAR VEMAP Data Group http://www.cgd.ucar.edu/vemap (1) Data Policy Use of the VEMAP 2 dataset is subject to the VEMAP data policy (www.cgd.ucar.edu/vemap/V2policy.html). Please register with the VEMAP Data Group in order to be informed of updates or revisions. Users are requested to confer with the NCAR VEMAP Data Group to ensure that the intended application of the dataset is consistent with the generation and limitations of the data. Please cite data as: 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. Kittel, T.G.F., NA Rosenbloom, C. Kaufman, JA Royle, C. Daly, H.H. Fisher, WP Gibson, S. Aulenbach, R. McKeown, D.S. Schimel, and VEMAP2 Participants (2000). VEMAP Phase 2 Historical and Future Scenario Climate Database. Available online at [http://www-eosdis.ornl.gov/] from the ORNL Distributed Active Archive Center, Oak Ridge National Laboratory, Oak Ridge, Tennessee, U.S.A. (2) VEMAP 2 Transient Climate Dataset - Historical Climate (a) Annual Files NetCDF annual files (99 years of annual records) Period of Record: 1895 - 1993 3261 non-background values for the contiguous US. The annual data are available on ORNL DAAC's anonymous FTP site: > ftp daacl.esd.ornl.gov > cd pub/data/vemap-2/TCLIMATE/annual/data > binary (Note: transfer files in binary mode) Filenames: irrxTCLMxxA3i.nc pptxTCLMxxA3i.nc rhumTCLMxxA3i.nc sradTCLMxxA3i.nc tmaxTCLMxxA3i.nc tminTCLMxxA3i.nc vpxxTCLMxxA3i.nc (b) Monthly Files NetCDF monthly files (99 years of monthly records = 1188 records) Period of Record: Jan 1895 - Dec 1993 3261 non-background values over the contiguous US. The monthly data are available on ORNL DAAC's anonymous FTP site: > ftp daacl.esd.ornl.gov > CD pub/data/VEMAP2/TCLIMATE/monthly/data > binary (Note: transfer files in binary mode) Filenames: irrxTCLMxxM3i.nc pptxTCLMxxM3i.nc rhumTCLMxxM3i.nc sradTCLMxxM3i.nc tmaxTCLMxxM3i.nc tminTCLMxxM3i.nc vpxxTCLMxxM3i.nc (c) Daily Files NetCDF daily files Period of Record: Jan 1895 - Dec 1993 3261 non-background values over the contiguous US. The daily data are available on ORNL DAAC's anonymous FTP site: > ftp daacl.esd.ornl.gov > CD pub/data/VEMAP2/TCLIMATE/daily/data > binary (Note: transfer files in binary mode) Filenames: irrxTCLMxxD3i.nc.gz pptxTCLMxxD3i.nc.gz rhumTCLMxxD3i.nc.gz sradTCLMxxD3i.nc.gz tmaxTCLMxxD3i.nc.gz tminTCLMxxD3i.nc.gz vpxxTCLMxxD3i.nc.gz They are available on CD through ORNL DAAC by contacting the ORNL DAAC's User Services Office at ornldaac@ornl.gov or at 865-241-3952 and on 8mm Exabyte tape through the NCAR VEMAP Data Group email: ckaufman@ucar.edu or nanr@ucar.edu (d) File Name Convention Example: pptxCCC1SuM4i.nc Formula: vvvvSSSSaaTrg.nc(.gz) where: vvvv = variable tmax = maximum temperature tmin = minimum temperature pptx = precipitation irrx = mean daily irradiance srad = total incident solar radiation rhum = relative humidity vpxx = vapor pressure SSSS = dataset TCLM = historical climate (1895-1993) CCC1 = CCCma CGCM1 scenario (1994-2100) HAD2 = Hadley HadCM2 scenario (1994-2099) TCC1 = hist clim + CCCma scen (1895-2100) TCH2 = hist clim + Hadley scen (1895-2099) aa = aerosol experiment Su = sulfate aerosols xx = not applicable T = time step A = annual M = monthly D = daily r = release number g = type of grid p = partial grid (only non-background grid cells in file) i = full (inflated) grid (all grid cells in file) nc = netCDF suffix gz = (applicable only if compressed) compressed using UNIX gzip utility Note (UNIX): To uncompress the files, type: gunzip .gz (e) Geography and VVEG Version Geographic information is included in each netCDF file describing the VEMAP grid: - latitude - longitude - time - elevation of cells with land cover [m] - varea: the area of each grid cell covered by land [km2] - vveg(v2): VEMAP vegetation classification - grid mask counter (1->3261 for non-background grid cells; 0 for background grid cells) This version of VVEG reflects minor changes to the classification and distribution of potential natural vegetation suggested during VEMAP Phase 1. For details on VVEG version 2, see Section 10 and Appendix 3 in "A User's Guide to the VEMAP Phase 1 Database" (available on the VEMAP web site [http://www.cgd.ucar.edu/vemap/users_guide.html] and hard copy). (f) Units Units are described in the netCDF file header. (g) NetCDF file format The files are written in netCDF format (binary rather that ASCII). (See the Appendix for more information on general NetCDF format and source code.) . The netCDF files contain monthly or annual values for each grid cell over the contiguous United States. Backgroud cells containing no data are represented as missing with -9999.0. This format is referred to as "full grid", as compared to the "partial grid" fomat of earlier VEMAP releases in which the file only included the non-background grid cells. The netCDF files are in sequential or "movie" format with the complete time slice of the U.S. for the first year, followed by the complete time slice of the US for the second year, etc. (i.e., (time,lat,lon)). The order of the grid cells is west to east, north to south. Each grid cell is 0.5 degree latitude by 0.5 degree longitude. The data values are given for the center of the grid cell. There are 3261 non-background cells out of 5520. (UNIX) To output a netCDF file to the screen in ASCII format, type: ncdump | more (or 'less') Or for just the header (meta data), type: ncdump -h | more (or 'less') (h) NetCDF Data Display and Analysis Many options exist to edit, display, and analyze data in netCDF format. NetCDF files can be read by C, FORTRAN, Java, and Perl programs using netCDF libraries. NCO (a suite of netCDF operators) provides command line options for editing, averaging, subsetting, and merging netCDF files. Other software programs are available to display and edit netCDF files on a variety of platforms. Descriptions of these and other netCDF tools can be found on the following web pages: http://www.cgd.ucar.edu/vemap/resources.html http://www.unidata.ucar.edu/packages/netcdf/software.html See the Appendix for more information on NetCDF. (3) Historical C02 Twice-yearly historical time series of global atmospheric CO2 concentration is provided in the ASCII file: co2.dat This dataset is based on the spline fit of Mauna Loa and ice core data from Enting et al. (1994), updated by T. Wigley (2000). The data start in 1765. (4) Wind Speed For a wind speed dataset, we recommend that modeling groups use the monthly wind data from VEMAP Phase1, stored in SVF ASCII format and available from the NCAR Data Group: ftp.ucar.edu/edas/vemap/scenario/w.MMM (5) Contacts If you have technical problems or questions about these files, please contact Cristina Kaufman or Nan Rosenbloom. Cristina Kaufman ph: +1-303-497-1713 email: ckaufman@ucar.edu Nan Rosenbloom ph: +1-303-497-1617 email: nanr@ucar.edu For questions regarding creation and content of the dataset, please contact Tim Kittel or Dave Schimel: Timothy Kittel ph: +1-303-497-1606 email: kittel@ucar.edu David Schimel ph: +1-303-497-1610 email: schimel@ucar.edu APPENDIX. NetCDF NetCDF refers to the Network Common Data Form developed by Unidata (within the University Corporation for Atmospheric Research). NetCDF software is an I/O library that is callable from C, FORTRAN, C++, Perl or other language for which a netCDF library is available. The library stores and retrieves scientific data structures using self-describing, machine-independent files. The netCDF source is freely available and can be obtained as a compressed tar file or a zip file from Unidata. Extensive documentation, source files, and software for manipulating or displaying netCDF data can be found online at: http://www.unidata.ucar.edu/packages/netcdf/ Please refer questions about building or installing netCDF software to UNIDATA http://www.unidata.ucar.edu/Support.html