[Wrf-users] how to extract upper level variables from wrfoutput(850, 700, 500, 200mb levels)

[afwande juliet]

I am trying to extract wrf variables for upper levels at
(850,700,500,200mb) using nco. I want to extract these variables pressure,
temp(tc),height(z), relative humidity(rh), ua and va winds, potential
vorticity(pvo) and vertical vorticity(wa). Then save the files as a .nc and
using other tools to plot and analyses them. I tried using NCO but it
doesn’t work, an error,
http://research.jisao.washington.edu/data_sets/nco/

ncea -d level,6,6 -F, v Times  XLAT,XLONG,pressure,tc,z,rh,ua,va,pvo,wa,
wrfout_d01_1997* -0 wrf_upper_var.nc

however, i get the errors below
ncea: ERROR nco_var_lst_mk() reports user-specified variable "pressure" is
not in input file" .

I believe these variables are present in the wrfoutput. Does someone
understand better how to go about it. I use always nco succesfully to
extract the surface variables like
(ncrcat -d Time,31,155 -v Times,XLAT,XLONG,RAINC,RAINNC,U10,V10,T2,HGT,PSFC
wrfout_d01_2015* -O wrf_2015_Oct_Rain_BML.nc)
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