METplus Practical Session Guide (Version 5.0) | MET Tool: Plot-Data-Plane > Plot GRIB Data

Plot GRIB Data

Start by creating a directory for our Plot-Data-Plane output:

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

Next, run Plot-Data-Plane to plot 2-meter temperature from a GRIB1 input file:

plot_data_plane \
${METPLUS_DATA}/met_test/data/sample_fcst/2005080700/wrfprs_ruc13_12.tm00_G212 \
${METPLUS_TUTORIAL_DIR}/output/met_output/plot_data_plane/ \
'name = "TMP"; level = "Z2";'

The default verbosity level of 2 only prints log messages about input and output files.

DEBUG 1: Opening data file: {...}/wrfprs_ruc13_12.tm00_G212
DEBUG 1: Creating postscript file: {...}/

Next, re-run at verbosity level 4 to see more detailed log message about the grid being read, timing information, and the range of the data values:

plot_data_plane \
${METPLUS_DATA}/met_test/data/sample_fcst/2005080700/wrfprs_ruc13_12.tm00_G212 \
${METPLUS_TUTORIAL_DIR}/output/met_output/plot_data_plane/ \
'name = "TMP"; level = "Z2";' -v 4

It is a great idea to inspect the log messages to sanity check the metadata. Without needing to understand all the details, does the grid definition look reasonable? Are the range of values reasonable for this variable type? Are the timestamps of the data consistent with the input file name?

Next, open the PostScript output file. On some machines, the ghostview utility (or common gv alias) can display PostScript files. On other, the display command works well. On Macs, simply run open. The example below uses gv which is available in the METplus AMI:

gv ${METPLUS_TUTORIAL_DIR}/output/met_output/plot_data_plane/

Optionally, if the convert utility is in your path, it can be run to change the image file format. Indicate the desired output file format by specifying the suffix (.png shown below).

which convert
convert -rotate 90 \
${METPLUS_TUTORIAL_DIR}/output/met_output/plot_data_plane/ \

The plot is created using the default color table (met_default.ctable) and is scaled to the range of valid data (275 to 305). By default, no title is provided and the input file is listed as a sub-title. Does the pattern of the data look reasonable? Does it correspond well to the background map data?

If the plot of the data and the metadata listed in the log messages look reasonable, you can be confident that MET is reading your data well. In addition, the field_string you used to retrieve this data can be used in the configuration strings and configuration files for other MET tools.

While this Plot-Data-Plane validation step is not necessary for every input file, it is very useful when getting started with new input data sources.