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====== Steps Followed To Extract VIL Above The Melting Level For A Particular Storm Track Using Different Methods ====== 

Three different methods are used to extract the VIL above the melting layer for a storm. The values thus obtained are compared with one another. A complete set of files used in this example is available here:{{ :atmos:software:lrose:projdir.olds_project_info.tar |}}

**DATE of Storm Occurrence:** 2017/07/09

**INSTANCE of Storm Occurrence Used In This Example:** 19:51:27 Zulu Time

**COORDINATES (respective to the Radar Origin) of Storm Used:** -30.16, -82.76

**COMPLEX Track Number:** 12

**SIMPLE Track Number:** 12


===== Manual Computation of VIL: =====

The Rview screen of TITAN is used for this method.

* Run Rview and select the storm which is to be studied.
  Rview -params ~/path/of/params/file/Rview.archive

Select the MaxdBz field and identify the coordinates inside the storm with the maximum value of MaxdBz.

Note the dBz values at these coordinates for every CAPPI level, starting from 2 km and all the way up to 14 km.

Use these values in the mathematical formula for computing the VIL. The VIL of the storm computed through the entire column of the storm came out as 49.44 kg/m^2. **The VIL above the melting layer came out as 25.24 kg/m^2.**

===== VIL Extraction Using TITAN: =====

* Generate the Titan params file using the following command from the command line: Titan params file is available here:{{ :atmos:software:lrose:titan.olds.params |}}
   Titan -print_params > ~/path/of/Titan/params/file/Titan.olds.params

* Change the following in the Titan params file:
  low_dbz_threshold = 45;
  high_dbz_threshold = 80;
  base_threshold = 4;

* To generate the storm track files (.th5 files), run Titan from the command line using the following command:
   Titan -start "2017 07 09 12 00 00" -end "2017 07 10 12 00 00" -params Titan.olds.params

* Generate the Tracks2Ascii params file using the following command from the command line: The Tracks2Ascii params file is available here: {{ :atmos:software:lrose:tracks2ascii.te.params |}}
  Tracks2Ascii -print_params > ~/path/of/params/file/Tracks2Ascii.te.params

* Make the following change in the Tracks2Ascii params file:
  target_entity = TRACK_ENTRY;
  sample_interval = -1;

* Run Tracks2Ascii from the command line using the following command:
   Tracks2Ascii -start "2017 07 09 12 00 00" -end "2017 07 10 12 00 00"-params ~/path/of/params/file/Tracks2Ascii.te.params >> ~/path/of/output_file.txt
   
A sample output file is available here: {{ :atmos:software:lrose:outputstorm20170709_12zto12z_vilalllevels_threshold_at_4km.params |}}

**//NOTE: The output file has been given the extension .params so that it could be uploaded to this webpage. It is a simple .txt file and should not be confused with a params file.
//**

Note the value of VIL from the list of fields in the output file. **The VIL above melting layer calculated in this example came out as 35.04 kg/m^2.**

**//NOTE: Exactly the same value of VIL is displayed on the Storm Hist window of Rview.//**

===== VIL Extraction Using Mdv2Vil: =====

* Generate the Mdv2Vil params file by running the following command from the command line: The Mdv2Vil params file is available here: {{ :atmos:software:lrose:mdv2vil.params |}}
   Mdv2Vil -print_params > ~/ingest/params/Mdv2Vil.params

* Make the following change in the params file: 
  min_height = 4;
The melting layer for our example is 4 km. Hence the minimum height value is set as 4 km.

* Run the application Mdv2Vil from the command line using the following command:

  Mdv2Vil -start "2017 07 09 12 00 00" -end "2017 07 10 12 00 00" -params ~/path/of/params/file/Mdv2Vil.params      
The input and output directories for this application should be specified in the params file.

* Change the working directory to ~/data/mdv and point the symbolic link to the directory containing the files with the VIL values above melting layer.
  ln -s directory_name vil

* Run Rview from the command line using the following command and note the value of VIL displayed inside the studied storm on the Rview screen.
   Rview -params ~/path/of/Rview/params/file/Rview.archive

**The VIL above melting layer obtained in our example is 28.6 kg/m^2.**