README_WRF_NCL_SCRIPTS (20 December 2000, Bill Skamarock)
                         (Updated: May 08, 2001, wrfhelp)
                       (Updated: April 24, 2002, wrfhelp)

In this directory are NCL scripts that can be used to produce 2D plots
of wrf output. 

cd to em/ directory, if you work with WRF mass model output.
cd to eh/ directory, if you work with WRF height model output.

To run NCL with these scripts, you need NCL and NCAR GRAPHICS on your
system.  See README_NCL for specific information concerning how to
acquire and set up NCL and NCAR GRAPHICS for your system.
Also, there is more information about some of the functions and
procedures used by the user scripts in README_NCL.

---

NCL links in fortran shareable object files for computing some
diagnostic quantities and for performing interpolations.  Presently,
only one fortran object needs to be built - wrf_user_fortran_util_0.  
To build the fortran object, try running one of the make_ncl_fortran 
csh scripts that will build the shared-object library

"make_ncl_fortran wrf_user_fortran_util_0"

There are a few versions of this script for different architectures in
this directory.  More information about creating the shared objects
can be found at

http://ngwww.ucar.edu/ngdoc/ng/ref/ncl/NclExtend.html#wrapit77

---

In the em/ directory, there are the following scripts:

-> for idealized cases:

wrf_em_b_wave.ncl	
wrf_em_qss.ncl
wrf_em_hill2d.ncl
wrf_em_squall_2d_x.ncl
wrf_em_squall_2d_y.ncl

-> for real-data:

wrf_em_real.ncl		plot SLP, sfc precip, 850, 700, 500, 300 wind/temp
			cross sections and skew-T diagrams
wrf_em_sfc.ncl		plot a few surface fields
wrf_em_slp.ncl		plot SLP
wrf_em_the.ncl		plot potential temp on selected model levels
wrf_em_qv.ncl		plot water vapor on selected model levels
wrf_em_qc.ncl		plot cloud water on selected model levels

---

In the eh/ directory are NCL scripts that will plot horizontal cross
sections, vertical cross sections, and skew-T plots.

-> Scripts for plotting on z, p or sigma (model) surfaces 

wrf_p_1.ncl      horizontal cross sections on constant pressure surfaces
wrf_z_1.ncl      horizontal cross sections on constant height surfaces
wrf_sigma_1.ncl  horizontal cross sections model surfaces

-> Vertical cross sections

wrf_vert_1.ncl   cross sections through a model grid point at a specified 
                 angle  (in this case cloud water and plane-normal,
                 plane-tangential winds, angle is in degrees, +
                 clockwise, north is 0 degrees)

-> skew-T plots at specified points

wrf_sk_1.ncl

-> plots precip accumulations

wrf_precip_1.ncl  surface precip plots for resolved and parameterized precip,
                  accumulated from integration start time
wrf_precip_2.ncl  surface precip plots for resolved and parameterized precip,
                  accumulated from last output time

-> standard plots for a real-data run

wrf_sp.ncl       msl pressure and precip plots, various pressure-level plots, 
                 some vertical cross sections and some soundings.

-> msl pressure

wrf_psl.ncl      msl pressure

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For idealized 3 dimensional cases, such as b_wave and quarter_ss, use

wrf_eh_b_wave.ncl 
wrf_eh_qss.ncl    

For 2-D cases:

wrf_eh_hill2d.ncl
wrf_eh_squall_2d_x.ncl
wrf_eh_squall_2d_y.ncl

---

These scripts can be run by entering

"ncl < script_file"

The scripts expect to find the wrf output file in the 
call to the function "addfile".  Edit the path to your wrfout file.

---

The scripts are ascii files, and they can be edited to change what is
plotted and where the output is directed.  To change where output is
directed, comment out the line (a comment is preceded by ";" in NCL scripts)

wks = wrf_open_X11()                ; output to screen

and uncomment one of the remaining choices

;wks = wrf_open_ncgm("wrf_plots")   ; output to ncgm (wrf_plots.ncgm)
;wks = wrf_open_PS("wrf_plots")     ; output to postscript (wrf_plots.ps)

Options for levels, data, etc. are in fairly obvious places in the scripts.

---

Any 2D and 3D data in the WRF netcdf output files can be plotted.  The
NCL function "wrf_user_getvar" extracts data from the output files.
Variables in the output files are all in capital letters
(use "ncdump -h wrf_output_file | more" to view what is in the file).
Lower case variables are diagnostics that can be computed.
Currently we have diagnostics computed for the following named variables.

umet -> u wind (parallel to latitude line, used for skew-T plots)
vmet -> v wind (parallel to longitude line, used for skew-T plots)
u -> u horizontal velocity (m/s) 
v -> v horizontal velocity (m/s)
w -> w vertical velocity (m/s)
ua -> u averaged to mass (p) points. (the center point on the C grid)
va -> v averaged to mass (p) points. (the center point on the C grid)
wa -> w averaged to mass (p) points. (the center point on the C grid)
om -> transformed vertical velocity from model
th -> potential temperature (theta)
p  -> pressure (mb)
tc -> temperature (Celsius)
td -> dewpoint temperature (Celsius)
rh -> relative humidity

For any other variable "wrf_user_getvar" will look in the output file.
If a variable is not found, NCL will produce error messages and 
will not produce any more plots.

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