Configure

Start by making an output directory for Gen-Ens-Prod and changing directories:

mkdir -p ${METPLUS_TUTORIAL_DIR}/output/met_output/gen_ens_prod

cd ${METPLUS_TUTORIAL_DIR}/output/met_output/gen_ens_prod

Similar to other MET tools, the behavior of Gen-Ens-Prod is controlled by the contents of the configuration file passed to it on the command line. The default Gen-Ens-Prod configuration file may be found in the data/config/GenEnsProdConfig_default file. The configurations used by the test script may be found in the scripts/config/GenEnsProdConfig* files.

Prior to modifying the configuration file, users are advised to make a copy of the default:

cp ${MET_BUILD_BASE}/share/met/config/GenEnsProdConfig_default GenEnsProdConfig_tutorial

Open up the GenEnsProdConfig_tutorial file for editing with your preferred text editor.

vi GenEnsProdConfig_tutorial

The configurable items for Gen-Ens-Prod are a more limited version of those found in tools such as Grid-Stat and Point-Stat. The reason for this is tied to the purpose of the tool: Gen-Ens-Prod is for creating simple ensemble products and not for statistical verification with observation datasets. This is made clear in the configuration file's use of the ensemble ens dictionary, rather than a forecast and observation dictionary.

ens = {
ens_thresh = 1.0;
vld_thresh = 1.0;

field = [
{
name = "APCP";
level = "A03";
cat_thresh = [ >0.0, >=5.0 ];
}
];
}

The configuration file also does not have the ability to request statistical line type output, instead allowing users to create ensemble products with the ensemble_flag dictionary.

ensemble_flag = {
latlon = TRUE;
mean = TRUE;
stdev = TRUE;
minus = TRUE;
plus = TRUE;
min = TRUE;
max = TRUE;
range = TRUE;
vld_count = TRUE;
frequency = TRUE;
nep = FALSE;
nmep = FALSE;
climo = FALSE;
climo_cdp = FALSE;
}

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

For this tutorial, we'll configure Ensemble-Stat to verify 24-hour accumulated precipitation. While we'll run Ensemble-Stat on a single field, please note that it may be configured to operate on multiple fields. The ensemble we're verifying consists of 6 members defined over the west coast of the United States.

In the ens dictionary, set

ens = {
ens_thresh = 0.5;
vld_thresh = 0.5;

field = [
{
name = "APCP";
level = "A24";
cat_thresh = [ >0.0, >=13.0, >=25.0, >=101.0];
}
];
}

Setting ens_thresh at 0.5 allows half of the ensemble member files being passed at runtime to contain invalid data and before GenEnsProd quits with an error. Similarly, vld_thresh at 0.5 allows each grid point to have invalid data for half of the ensemble member files passed at runtime and still compute the requested products for that grid point.

In the ensemble_flag dictionary, set

ensemble_flag = {
latlon = TRUE;
mean = TRUE;
stdev = TRUE;
minus = FALSE;
plus = FALSE;
min = FALSE;
max = FALSE;
range = FALSE;
vld_count = TRUE;
frequency = TRUE;
nep = FALSE;
nmep = FALSE;
climo = FALSE;
climo_cdp = FALSE;
}

These products will be output to the netCDF designated at runtime with the -out flag. They will show a small sample of the options from Gen-Ens-Prod, as well as highlighting how the output changes when one of the files is entered as the control ensemble member, which will be done later this session.

Save and close this file.

jopatz Wed, 01/18/2023 - 14:07