===========================
NCAR Command Language (NCL)
===========================

|

`NCL <https://www.ncl.ucar.edu/>`_ is an interpreted language designed for scientific data analysis and visualization.

|

.. note::
   *   You will be using NCL version 6.6.2, which includes all functions necessary for creating plots 
   *   We recommend using an existing sample script as template, and then modifying it to suit your needs, if you want to make modifications

|


Available NCL Scripts
=====================

Below are the pre-written sample scripts are available from your *wrf/test/em_real* directories, but can also be found in */glade/campaign/mmm/wmr/wrf_tutorial/WRF_NCL_scripts*.

|

Scripts for Real-data Cases
---------------------------

|

.. csv-table::
   :widths: 25, 25, 25
   :width: 75%
   
   CreateTracks.ncl, wrf_AdaptiveTime.ncl, wrf_cape.ncl
   wrf_Cloud.ncl, wrf_Cross2D.ncl, wrf_CrossSection_1.ncl
   wrf_CrossSection1.ncl,wrf_CrossSection_2.ncl,wrf_CrossSection2.ncl
   wrf_CrossSection_3.ncl,wrf_CrossSection3.ncl,wrf_CrossSection_4.ncl
   wrf_CrossSection4.ncl,wrf_CrossSection_add_smooth_terrain4.ncl,wrf_CrossSection_add_smooth_terrain.ncl
   wrf_dbz1.ncl, wrf_dbz2.ncl,wrf_EtaLevels.ncl
   wrf_eth.ncl,wrf_Height2.ncl, wrf_Height.ncl
   wrf_helicity.ncl,wrf_meteo_1.ncl,wrf_meteo_2.ncl
   wrf_meteo_3.ncl,wrf_meteo_4.ncl,wrf_meteo_5_limited_height.ncl
   wrf_meteo_5.ncl, wrf_metgrid1.ncl,wrf_metgrid2.ncl
   wrf_metgrid3.ncl,wrf_metgrid4.ncl, wrf_metgrid5.ncl
   wrf_metgrid6.ncl,wrf_metgrid7.ncl,wrf_metgrid8.ncl
   wrf_moving_nest.ncl,wrf_moving_nest_overlap.ncl,wrf_moving_nest_precip_2doms.ncl
   wrf_moving_nest_precip.ncl, wrf_overlay_doms.ncl,wrf_Overlay.ncl
   wrf_panel1-1.ncl,wrf_panel1-2.ncl, wrf_panel1.ncl
   wrf_panel2-2.ncl,wrf_panel2.ncl,wrf_Precip2.ncl
   wrf_Precip3.ncl,wrf_Precip_multi_files.ncl,wrf_PressureLevel1.ncl
   wrf_PressureLevel2.ncl, wrf_PressureLevel3.ncl,wrf_pv.ncl
   wrf_PW2.ncl,wrf_PW3.ncl, wrf_PW.ncl
   wrf_SkewT1.ncl,wrf_SkewT2.ncl,wrf_SkewT3.ncl
   wrf_SkewT4.ncl,wrf_SkewT5.ncl,wrf_SkewT.ncl
   wrf_Surface1.ncl, wrf_Surface2.ncl,wrf_Surface3.ncl
   wrf_Surface_multi_files_avg.ncl,wrf_Surface_multi_files.ncl, wrf.ts.ncl
   wrf_updraft_helicity.ncl,wrf_wind_rose.ncl,wrf_wps_plot_all.ncl
   wrf_wps_ter1.ncl,wrf_wps_ter2.ncl,wrf_wps_ter3.ncl
   wrf_wps_ter4.ncl, wrf_wps_ter5.ncl,wrf_wps_ter6.ncl
   wrf_Zoom.ncl,olr.ncl, get_wrf_file_dims.ncl
   gWRF_merc.ncl,design_grids.ncl, ""

|

For beginners wanting to plot a single wrf output file (*wrfout\**), the following scripts are recommended:

*   wrf_CrossSection_1.ncl
*   wrf_EtaLevels.ncl
*   wrf_Height.ncl
*   wrf_PressureLevel1.ncl
*   wrf_Surface1.ncl
*   wrf.ts.ncl

|

For beginners wanting to plot multiple wrf output file (*wrfout\**), the following scripts are recommended:

*   wrf_Precip_multi_files.ncl 
*   wrf_Surface_multi_files 

|

|

|

Scripts for Idealized Cases
---------------------------

|

.. csv-table::
   :width: 35%

   wrf_BWave.ncl
   wrf_Grav2x.ncl
   wrf_Hill2d.ncl
   wrf_QSS.ncl
   wrf_Squall_2d_x.ncl
   wrf_Squall_2d_y.ncl

|

|

|

|

Running an NCL Script
=====================

|

#.   Create your own script, or pick one from of the supplied scripts. If you start with a supplied script, most often all you need to do is change the input file, in this line:

     |
     
     .. code-block::

        a = addfile("./wrfout_d01_2023-03-31_00:00:00 .nc","r")

     |

     .. note::
        You do not need to change your filenames so that they have a trailing *.nc*. But KEEP the trailing *.nc* in the above line, as this is used as a file type communicator to NCL.

     |

     |

#.   Run the script

     |
     
     .. code-block::
        :class: copyable

        ncl <script>

     |

     The output depends on your setting of "type" in the scripts. `See detailed running instructions <http://www2.mmm.ucar.edu/wrf/OnLineTutorial/Graphics/NCL/index.php>`_ from the WRF Online Tutorial.

|

|

|

|

|

Return to the Practice Exercise home to page to run another exercise. 

.. rst-class:: horizbuttons-primary-m

* `Return to Practice Exercises <./practices.html>`_

|

|

|








.. seealso::
   *   The `NCL section from the WRF Users' Guide <https://www2.mmm.ucar.edu/wrf/users/wrf_users_guide/build/html/post_processing.html#ncar-command-language-ncl>`_
   *   The `NCL section from the WRF Online Tutorial <https://www2.mmm.ucar.edu/wrf/OnLineTutorial/Graphics/NCL/index.php>`_
   *   The `NCL Post-processing video presentation <https://www.youtube.com/watch?v=4NT02-RMLVc&list=PLJ_1sjucSSZCTNBRM4D3BfEak-XT7TKJo&index=8&pp=iAQB>`_
   *   The `NCL Post-processing .pdf presentation <https://www2.mmm.ucar.edu/wrf/users/tutorial/presentation_pdfs/202101/jaye_ncl.pdf>`_



|


|

.. toctree::
   :maxdepth: 4
   :hidden:

|

|

|

|