The land use data sets developed at SAGE have a native resolution of 0.5 degree in latitude x longitude. Here users can choose to interpolate their variable of choice into any resolution, including latitude x longitude grids or Gaussian grids (the latter are normally used by global climate models). For Gaussian grids, we currently support only seven types (see pull down menu to the right) - please contact us if you would like to see a different Gaussian grid option.
Data can be output in either ASCII format or NetCDF format. Please note that a land-ocean mask is created "on the fly". It uses a fairly generous definition of land (>20% land fraction) in order to include different masks used by different groups. Please let us know if our mask generates ocean points in grid cells where you have land.
The output ASCII file will have a header of 6 or 7 lines describing the parameters of the output data, and the remaining lines have data written out sequentially from west to east starting from the northwestern most grid cell, with data in each new latitude starting a new line. The output ASCII file can be read using the following FORTRAN program (read_ascii.f). The output of this FORTRAN program will be a simple data table with each row containing a longitude, latitude, and data value. If your choice is a regular latitude x longitude grid (i.e., x resolution = y resolution), then the output ASCII file can be directly imported into ArcGIS software.
For detailed information about the NetCDF format, go to the UCAR Unidata Program Center (http://www.unidata.ucar.edu/packages/netcdf/).
Panoply, a free NetCDF viewing software package, is available at http://www.giss.nasa.gov/tools/panoply/.
Enter Lat. and Lon. resolutions (in degrees, for e.g., 3.0, 2.0) that are divisors of 180 and 360, respectively, or choose the type of gaussian grid that you want.
Please choose output option:
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Questions about the page or data?
contact Navin Ramankutty
This database interface was written by Seth Price.