MET Online Tutorial for METv3.0

COPYGB Tool: Run

In this tutorial, we'll run COPYGB several times to do the following:

  1. Interpolate to a pre-defined NCEP grid.
  2. Interpolate to a user-defined Lat/Lon grid.
  3. Interpolate to a user-defined Lambert Conformal grid.
  4. Interpolate to a user-defined Polar Stereographic grid.

Pre-Defined NCEP Grid

First, we'll run the wgrib tool to dump out information about a sample GRIB file:

    wgrib -V data/sample_obs/ST2ml/ST2ml2005080712.Grb_G212

The -V argument for wgrib dumps out the definition of the grid on which the data resides. This data is on a Lambert Conformal grid with the grid definition parameters listed below:

    Lambert Conf: Lat1 12.190000 Lon1 -133.459000 Lov -95.000000
    Latin1 25.000000 Latin2 25.000000 LatSP 0.000000 LonSP 0.000000
    North Pole (185 x 129) Dx 40.635000 Dy 40.635000 scan 64 mode 8

This data resides on NCEP Grid 212 (image), a 40-km Lambert Conformal grid over the contiguous United States. Now run COPYGB on this file to interpolate this data to NCEP Grid 202 (image), a 190-km Polar Stereographic grid:

    mkdir -p tutorial/out/copygb

    copygb.exe \
    -xg 202 \
    data/sample_obs/ST2ml/ST2ml2005080712.Grb_G212 \
    tutorial/out/copygb/ST2ml2005080712.Grb_G202

In the command above the -x option indicates that we want the data to be extracted and the -g 202 option indicates that the data should be interpolated to NCEP Grid 202. Next, run wgrib on the output and note that the grid definition has changed:

    wgrib -V tutorial/out/copygb/ST2ml2005080712.Grb_G202

The resulting grid definition parameters are listed below:

    polar stereo: Lat1 7.838000 Long1 -141.028000 Orient -105.000000
    north pole (65 x 43) Dx 190500 Dy 190500 scan 64 mode 9

For a list of the pre-defined NCEP grids available, please see:
http://www.nco.ncep.noaa.gov/pmb/docs/on388/tableb.html