METplus Practical Session Guide (Version 4.0) | Session 2: Grid-to-Obs > METplus Use Case: PointStat - Standard Verification for CONUS Surface

IMPORTANT NOTE: If you are returning to the tutorial, you must source the tutorial setup script before running the following instructions. If you are unsure if you have done this step, please navigate to the Verify Environment is Set Correctly page.

METplus Use Case: PointStat - Standard Verification of CONUS Surface

This use case utilizes the MET Point-Stat tool. 

Optional: Refer to the MET Users Guide for a description of the MET tools used in this use case.
Optional: Refer to the METplus Config Glossary section of the METplus Users Guide for a reference to METplus variables used in this use case.

  1. View Configuration File
Change to the ${METPLUS_TUTORIAL_DIR} directory:
cd ${METPLUS_TUTORIAL_DIR}
Define a unique directory under output that you will use for this use case. In the example below, we'll  override OUTPUT_BASE to that directory on the command line.
less ${METPLUS_BUILD_BASE}/parm/use_cases/model_applications/medium_range/PointStat_fcstGFS_obsNAM_Sfc_MultiField_PrepBufr.conf

Many of the options are similar, except the fields typically at the surface (BOTH_VARn_LEVELS = Z2 and Z10 or integrated BOTH_VARn_LEVELS = L0). Also, the Point-Stat MESSAGE_TYPE is set to a specific keyword ONLYSF for only surface fields. Finally, the PB2NC_INPUT_TEMPLATE includes a da_init specification in the input template to help determine the valid time of the data.

POINT_STAT_MESSAGE_TYPE = ONLYSF
...
PB2NC_INPUT_TEMPLATE = nam.{da_init?fmt=%Y%m%d}/nam.t{da_init?fmt=%2H}z.prepbufr.tm{offset?fmt=%2H}

Using this configuration file, you should be able to run the use case using the sample input data set without any other changes.

  1. Run the PointStat use case
run_metplus.py \
${METPLUS_BUILD_BASE}/parm/use_cases/model_applications/medium_range/PointStat_fcstGFS_obsNAM_Sfc_MultiField_PrepBufr.conf \
${METPLUS_TUTORIAL_DIR}/tutorial.conf \
config.OUTPUT_BASE=${METPLUS_TUTORIAL_DIR}/output/PointStat_Sfc
  1. Review the output files
ls ${METPLUS_TUTORIAL_DIR}/output/PointStat_Sfc/nam
less ${METPLUS_TUTORIAL_DIR}/output/PointStat_Sfc/nam/point_stat_000000L_20170601_000000V.stat

Inspection of the file shows that statistics for TMP, RH, UGRD, VGRD, UGRD_VGRD are available. Also, based on the number listed after the line type (SL1L2 and VL1L2), there are between 8263 - 9300 points included in the computation of the statistics. The big question is why are there no statistics for TCDC and PRMSL? Let's look at the log files.

ls ${METPLUS_TUTORIAL_DIR}/output/PointStat_Sfc/logs

Open the log file and search on TCDC, you will see that there is an error message stating "no fields matching TCDC/L0 found" in the GFS file. That is why TCDC does not appear in the output.

Look for PRMSL/Z0 in the log file.  We can see the following:

DEBUG 2: Processing PRMSL/Z0 versus PRMSL/Z0, for observation type ONLYSF, over region FULL, for interpolation method BILIN(4), using 0 matched pairs.
DEBUG 2: Number of matched pairs = 0
DEBUG 2: Observations processed = 441178
DEBUG 2: Rejected: station id = 0
DEBUG 2: Rejected: obs var name = 441178

You will note, the number of observations processed is the same as the number rejected due to a mismatch with the obs var name. That suggests we need to look at how the OBS variable for PRMSL is defined.

  1. Inspect configuration file and plot fields
less ${METPLUS_BUILD_BASE}/parm/use_cases/model_applications/medium_range/PointStat_fcstGFS_obsNAM_Sfc_MultiField_PrepBufr.conf

Note that PB2NC_OBS_BUFR_VAR_LIST = PMO, TOB, TDO, UOB, VOB, PWO, TOCC, D_RH, where PMO is the identifier for MEAN SEA-LEVEL PRESSURE OBSERVATION according to https://www.nco.ncep.noaa.gov/sib/decoders/BUFRLIB/toc/prepbufr/prepbufr_bftab/. Let's use Plot-Data-Plane to confirm this identifier will provide valid observations for Point-Stat to use.

plot_point_obs \
${METPLUS_TUTORIAL_DIR}/output/PointStat_Sfc/nam/conus_sfc/20170601/nam.2017060100.nc \
${METPLUS_TUTORIAL_DIR}/output/PointStat_Sfc/nam/conus_sfc/20170601/nam.2017060100.ps \
-obs_var PMO
Convert to PNG and display
convert -rotate 90 \
${METPLUS_TUTORIAL_DIR}/output/PointStat_Sfc/nam/conus_sfc/20170601/nam.2017060100.ps \
${METPLUS_TUTORIAL_DIR}/output/PointStat_Sfc/nam/conus_sfc/20170601/nam.2017060100.png

display ${METPLUS_TUTORIAL_DIR}/output/PointStat_Sfc/nam/conus_sfc/20170601/nam.2017060100.png

  1. Update configuration file and re-run
Open up the PointStat2 conf file and examine the definition of variables. Note that we might want to try changing the BOTH_VAR7_NAME to FCST_VAR7_NAME and OBS_VAR7_NAME:
Copy the configuration file to the user_config directory and open for editing:
cp ${METPLUS_BUILD_BASE}/parm/use_cases/model_applications/medium_range/PointStat_fcstGFS_obsNAM_Sfc_MultiField_PrepBufr.conf ${METPLUS_TUTORIAL_DIR}/user_config/PointStat_Sfc2.conf
vi ${METPLUS_TUTORIAL_DIR}/user_config/PointStat_Sfc2.conf
FCST_VAR7_NAME = PRMSL
FCST_VAR7_LEVELS = Z0

OBS_VAR7_NAME = PMO
OBS_VAR7_LEVELS = Z0

run_metplus.py \
${METPLUS_TUTORIAL_DIR}/user_config/PointStat_Sfc2.conf \
${METPLUS_TUTORIAL_DIR}/tutorial.conf \
config.OUTPUT_BASE=${METPLUS_TUTORIAL_DIR}/output/PointStat_Sfc2
less ${METPLUS_TUTORIAL_DIR}/output/PointStat_Sfc2/nam/point_stat_000000L_20170601_000000V.stat

There is now a line with PRMSL listed and statistics reported.