METplus Practical Session Guide (Version 5.0) | MET Tool: PCP-Combine > Output

When PCP-Combine is finished, you may view the output NetCDF files it wrote using the ncdump and ncview utilities. Run the following commands to view contents of the NetCDF files:

ncview &
ncview &
ncdump -h
ncdump -h

The ncview windows display plots of the precipitation data in these files. The output of ncdump indicates that the gridded fields are named APCP_12, the GRIB code abbreviation for accumulated precipitation. The accumulation interval is 12 hours for both the forecast (3-hourly * 4 files = 12 hours) and the observation (1-hourly * 12 files = 12 hours).

Note, if ncview is not found when you run it on your system, you may need to load it first.  For example, on hera, you can use this command:

 module load ncview

Plot-Data-Plane Tool

The Plot-Data-Plane tool can be run to visualize any gridded data that the MET tools can read. It is a very helpful utility for making sure that MET can read data from your file, orient it correctly, and plot it at the correct spot on the earth. When using new gridded data in MET, it's a great idea to run it through Plot-Data-Plane first:

plot_data_plane \ \ \
'name="APCP_12"; level="(*,*)";'
gv &

Ghostview (gv) can take a little while before it displays.  If you don't have gv on your computer, try using display, or any tool that can visualize PostScript files, e.g.:

display &

Another option is to create a PNG file from the PS file, also rotating it to appear the right way:

convert -rotate 90 \
display sample_fcst_12L_2005080712V_12A.png

Next try re-running the command list above, but add the convert(x)=x/25.4; function to the config string (Hint: after the level setting and ; but before the last closing tick) to change units from millimeters to inches. What happened to the values in the colorbar?

Now, try re-running again, but add the censor_thresh=lt1.0; censor_val=0.0; options to the config string to reset any data values less 1.0 to a value of 0.0. How has your plot changed?

The convert(x) and censor_thresh/censor_val options can be used in config strings and MET config files to transform your data in simple ways.