METplus Practical Session Guide (Version 4.0) | MET Tool: PB2NC > Reconfigure and Rerun

PB2NC Tool: Reconfigure and Rerun

Now we'll rerun PB2NC, but this time we'll tighten the observation acceptance criteria.

Start by making a copy of the configuration file we just used:
cp PB2NCConfig_tutorial_run1 PB2NCConfig_tutorial_run2
Open up the PB2NCConfig_tutorial_run2 file and edit it as follows:
vi PB2NCConfig_tutorial_run2
  • Set:
    message_type = [];

    to retain all message types.

  • Set:
    obs_window = {
       beg = -25*30;
       end =  25*30;
    }

    so that only observations 25 minutes before and 25 minutes after the top of the hour are retained.

  • Set:
    quality_mark_thresh = 1;

    to retain only the observations marked "Good" by the NCEP quality control system.

Next, run PB2NC again but change the output name using the following command:
pb2nc \
${METPLUS_DATA}/met_test/data/sample_obs/prepbufr/ndas.t00z.prepbufr.tm12.20070401.nr \
tutorial_pb_run2.nc \
PB2NCConfig_tutorial_run2 \
-v 2
If this run fails due to runtime issues, please download a copy of the output file here and manually save it as tutorial_pb_run2.nc.
Inspect the PB2NC status messages and note that 3972 observations were retained rather than 52491 in the previous example.

The majority of the observations were rejected because their valid time no longer fell inside the tighter obs_window setting.

When configuring PB2NC for your own projects, you should err on the side of keeping more data rather than less. As you'll see, the grid-to-point verification tools (Point-Stat and Ensemble-Stat) allow you to further refine which point observations are actually used in the verification. However, keeping a lot of point observations that you'll never actually use will make the data files larger and slightly slow down the verification. For example, if you're using a Global Data Assimilation (GDAS) PREPBUFR file to verify a model over Europe, it would make sense to only keep those point observations that fall within your model domain.