Grid-Stat Tool: Configure

The behavior of Grid-Stat is controlled by the contents of the configuration file passed to it on the command line. The default Grid-Stat configuration file may be found in the METv1.1/data/config/GridStatConfig_default file. The configurations used by the test script may be found in the METv1.1/data/config/GridStatConfig* files. Prior to modifying the configuration file, users are advised to make a copy of the default: cp data/config/GridStatConfig_default tutorial/config/GridStatConfig_tutorial

Open up the tutorial/config/GridStatConfig_tutorial file for editing with your preferred text editor.

The configurable items for Grid-Stat are used to specify how the verification is to be performed. The Grid-Stat configuration file should look very similar to the one for Point-Stat. The configurable items include specifications for the following:

• The forecast fields to be verified at the specified vertical level or accumulation interval.
• The threshold values to be applied.
• The areas over which to aggregate statistics - as predefined grids or configurable lat/lon polylines.
• The confidence interval methods to be used.
• The smoothing methods to be applied (as opposed to interpolation methods).
• The types of verification methods to be used.

You may find a complete description of the configurable items in section 5.3.2 of the MET User's Guide or in the comments of the configuration file itself. Please take some time to review them.

For this tutorial, we'll configure Grid-Stat to verify the 12-hour accumulated precipitation output of PCP-Combine. We'll be using Grid-Stat to verify a single field using NetCDF input for both the forecast and observation files. However, in general, GRIB files or the NetCDF output of PCP-Combine may be passed to Grid-Stat for either the forecast or observation files or both, and Grid-Stat may be used to verify more than one field at a time. Edit the tutorial/config/GridStatConfig_tutorial file as follows:

• Set vx_grib_code[] = [ "APCP/A12" ]; to verify the field of precipitation accumulated over 12 hours.
• Set thresholds[] = [ "gt0.0 ge5.0 ge10.0" ]; to select 3 threshold values of interest.
• Set mask_grids[] = [ "G212" ]; to accumulate statistics over the NCEP Grid 212 region.
• Set mask_polys[] = [ "MET_BASE/data/poly/EAST.poly" ]; to also accumulate statistics over the Eastern United States as defined by the polyline selected.
• Set nbr_width[] = [ 3, 5 ]; to select two neighborhood sizes over which to accumulate neighborhood statistics.
• Set nbr_frac_threshold[] = [ "ge0.5 ge0.75" ]; to define the fractional coverage threshold values of interest.
• Set output_flag[] = [ 0, 2, 0, 0, 0, 2, 2, 2, 2, 2, 2, 1 ]; to indicate that contingency table counts (CTC), contingency table statistics (CTS), continuous statistics (CNT), scalar partial sums (SL1L2), neighborhood contingency table counts (NBRCTC), neighborhood contingency table statistics (NBRCTS), neighborhood continuous statistics (NBRCNT), and the NetCDF difference field should be output.