View source for Plotting WRF Model output with GMT (Generic Mapping Tools)

In the [[WRF Weather Forecast for Sri Lanka|real-time weather forecast page for Sri Lanka]], I plot [[WRF]] model output using [[GMT]] (Generic Mapping Tools) rather than standard plotters provided by the model developers. Following is the method to do it. 

==Dependencies==
;Need the following programs installed:
:# NetCDF [http://www.unidata.ucar.edu/software/netcdf/]]
:# [[GMT]] version >= 4.0 [http://gmt.soest.hawaii.edu/]
:# [[gifsicle]] program for making GIF animations. [http://www.lcdf.org/gifsicle/]
:# Portland group FORTRAN compiler (for Linux) or any other suitable FORTRAN compiler.

==Download==
Version 2: With a few improvements.
[[Image:wrfGMTplot.tar.gz]]

==Usage==
# Compile the FORTRAN program <tt>./pltprogs/read_wrf_nc.f</tt> to produce the executable read_wrf_nc
# Edit the file <tt>./pltprogs/CONSTANTS.bash</tt> to reflect the paths in your computer. (Only <tt>GMT</tt>, <tt>convert</tt> and <tt>gifs</tt> entries need changing). Further change <tt>wrfntimes</tt> to indicate how many snapshots of output from the start of the model, needs processing. This should be less or equal to total number of output snapshots.  ( This is <tt>(Forecast length)/(output time step)</tt>)
# Go to the directory where <tt>wrfplot.bash</tt>. Copy or link the wrf output file to this place. 
# Execute the following command
<pre><nowiki>./wrfplot.bash</nowiki></pre>

Upon successful execution the <tt>png</tt> format images and datasets used to plot them will be available in the folder <tt>./output</tt>.


==Data in a single file==
Some programs/utilities that use WRF model output (e.g. Hydrological/Hydraulic models, GIS) may need all data snapshots to be compiled in a single file. Following is a utility that can be used to convert the results of the above utility to a single snapshot. Simply unzip the program in the directory where <tt>wrfplot.bash</tt> is and run it.
;The program: [[image:wrfplot_foldup.zip]]
;Running it: 
<nowiki>
 </nowiki>
<pre><nowiki>
unzip wrfplot_foldup.zip
chmod u+x foldup.bash
./foldup.bash
</nowiki></pre>
==Extracting a single column of data==
Use the following script
<nowiki>
 </nowiki>
<pre><nowiki>
#!/bin/bash
if [ $# -lt 1 ]; then 
        echo "Usage: $0 <datafile> <column number>"
        echo " NOTE: column number ignoring date columns"
        exit 5
fi
col=$(( $2 + 6 ))
cat $1|awk -v col=$col '{print $1, $2, $3, $4, $5, $6, $col}' > $1.$2.txt
</nowiki></pre>


[[Category:Hydrology-Meteorology]][[Category:Computing]][[Category:Unix]][[Category:WRF Model]]