On this page, we provide examples for using the "track" masking type using BEST track hurricane data and "circle" masking type.
Start by extracting the lat/lon locations for Hurricane Dorian:
Inspect the dorian.poly file that begins with "DORIAN" and has the lat/lon storm locations on subsequent lines.
Compute a mask for all grid points within 200 km of the Hurricane Dorian track. Run Gen-Vx-Mask using the following command:
G003 \
${METPLUS_TUTORIAL_DIR}/output/met_output/gen_vx_mask/dorian.poly \
${METPLUS_TUTORIAL_DIR}/output/met_output/gen_vx_mask/Dorian_Track.nc \
-type track -name Dorain_Track -thresh le200
Extract the first track point for Dorian and use the circle masking option to select all grid points within 500 km:
Run Gen-Vx-Mask on the command line using the following command:
G003 \
${METPLUS_TUTORIAL_DIR}/output/met_output/gen_vx_mask/dorian_first.poly \
${METPLUS_TUTORIAL_DIR}/output/met_output/gen_vx_mask/Dorian_Origin.nc \
-type circle -name Dorain_Track -thresh le500
The "circle" mask type draws a circle around each of the lat/lon points in the input poly file. The "circle" option may be useful when verifying within a certain radius of known radar locations. If you rerun without the "-thresh" command line option, Gen-Vx-Mask still runs but prints a warning message:
Can you figure out what this output file now contains? Run ncview or plot_data_plane to visualize it.
Gen-Vx-Mask also supports the "box", "solar_azi", and "shape" masking types, not covered in these exercises. Interested users can download Natural Earth shapefiles and run Gen-Vx-Mask using the "-type shape" option.
Next, we'll take a look at using the "shape" masking type with Gen-Vx-Mask.
