[ncl-talk] Subsetting WRF output file

[Jim Means]

I'm trying to do something which I think should be relatively simple, 
but I think my lack of understanding of gridded files is causing me 
problems.

I'd like to take the NetCDF output file from a WRF run and just pull out 
the variables I need, so that I have a smaller version of the file that 
I can work with. I'm giving it to somebody to load into IDV and they 
need to be able to aggregate times. I would like to be able to plot 
horizontal and vertical velocity at different levels in the model, and 
keep the time information so that I can see the evolution. My program 
runs, but IDV tells me that there is "No gridded data" found in my 
output file.

My question is what do I need to do to make this a gridded data file?

Here is some example code, I used unstagger because I thought that might 
be my problem, but unstaggering didn't seem to help.

Thanks,

Jim


begin
;

;***************************************************
; Open full NetCDF file and get variable names
;***************************************************

  nc_in = addfile("wrfout_d02_2018-07-22_06:00:00.nc","r")


;***************************************************
; Open output netcdf file. Remove first just in case.
;***************************************************
    nc_out_fname = "testout.nc"
    system("rm -f " + nc_out_fname) ; remove any pre-existing file
    ncdf_out = addfile(nc_out_fname,"c")


;***************************************************
; Specify desired  variables
;***************************************************

lat = nc_in->XLAT
lon = nc_in->XLONG
znu = nc_in->ZNU
u = nc_in->U
v = nc_in->V
w = nc_in->W
  ua = wrf_user_unstagger(u,u at stagger)
  va = wrf_user_unstagger(v,v at stagger)
  wa = wrf_user_unstagger(w,w at stagger)

xtime = nc_in->XTIME


ncdf_out->LAT = lat
ncdf_out->LON = lon
ncdf_out->ZNU = znu
ncdf_out->U = ua
ncdf_out->V=va
ncdf_out->W=wa

ncdf_out->XTIME = xtime

end

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Untitled Document

James D. Means, Ph.D.
Senior Atmospheric & Climate Scientist
California Office
Tele: 619-495-1638 | Fax: 775-636-8430
930 Tahoe Blvd., Suite 802-560
Incline Village, Nevada 89451
jim at weatherextreme.com <mailto:jim at weatherextreme.com> | vcard 
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