Re: Using NCL to generate WRF Ensemble plots

From: Dennis Shea <shea_at_nyahnyahspammersnyahnyah>
Date: Sun Dec 26 2010 - 09:13:21 MST

> I'm new the NCL mailing list and was wondering if someone could answer a quick question. Is it possible to take a collection of WRF simulations...either the WRF netCDF or Grib and generate ensemble images, such as mean, spread, spaghetti using NCL.

Yes.

----
[1]
NCL can handle either netCDF or GRIB formatted data files.
If you have
WRF_1.nc or WRF_1.grb
WRF_2.nc or WRF_2.grb
          :
WRF_N.nc or WRF_N.grb
  load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/contributed.ncl"
  dirw = "/my/wrf_files/"    ; input directory
  filw = systemfunc("cd "+dirw+" ; ls WRF_*nc)   ; or WRF_*grb
  print(filw)
  f    = addfiles (dirw+filw, "r")   ; note the "s" of addfile
  ListSetType (f, "join")
  T    = f[:]->T                     ; read T from all files
  printVarSummary (T) ; (ncl_join,Time,bottom_top,south_north,west_east)
The ncl_join dimension will be size N, corresponding to each
ensemble member.
  Te   = dim_avg_n_Wrap(T, 0)   ; average over all ensemble members
  printVarSummary(Te)
Use assorted NCL graphics to generated what you want. See:
http://www.ncl.ucar.edu/Applications/
and/or
http://www.mmm.ucar.edu/wrf/OnLineTutorial/Graphics/NCL/
Above functions:
http://www.ncl.ucar.edu/Document/Functions/Built-in/addfiles.shtml
See Example 2
http://www.ncl.ucar.edu/Document/Functions/Contributed/dim_avg_n_Wrap.shtml
[2]
The netCDF Operator (NCO) named "ncea" could be used on WRF netCDF files
to generate ensemble averages and be saved to a netCDF file.
http://nco.sourceforge.net/nco.html
http://linux.die.net/man/1/ncea
---
good Luck
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Received on Sun Dec 26 09:13:28 2010

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