Example 4. Extract various levels from various fields from ERA monthly mean data

#! /usr/bin/env convsh

#  Convsh script getuvw.tcl
#
#  Extract various levels from various fields in ERA monthly mean,
#  pressure level GRIB files, where the ERA data is contained in directory
#  /work/n02/n02/jwc/data on Archer, and write out as a netCDF file.

#  Write out netCDF file
set outformat netcdf

#  Automatically work out input file type
set filetype 0

#  Convert omega, u and v to netCDF
#  (use Xconv on one file to get field numbers)
set fieldlist "2 5 6"

#  Extract omega (2) on pressure levels 300 mb 500 mb and 700 mb.
#  (use Xconv on one file to get level numbers)
set levellist1 "8 10 12"

#  Extract u and v (5 and 6) on pressure levels 200 mb 925 mb and 1000 mb.
set levellist2 "6 15 16"

#  Era data is contained in /work/n02/n02/jwc/data directory
set dir /work/n02/n02/jwc/data

#  Read in each of the ERA monthly mean, pressure level files and
#  write omega, u and v fields to the output file, on specified levels

foreach infile [glob $dir/era-20c_plev_1.125x1.125_*.grib] {

#  Replace input file extension with .nc and append uvw_ to input
#  file name to get output filename
   set outfile "uvw_[file tail [file rootname $infile].nc]"

#  Read input file
   readfile $filetype $infile

#  Set the output level dimensions for the output fields
   setdim 3 "2" $levellist1
   setdim 3 "5 6" $levellist2

#  Write out omega, u and v fields to a netCDF file
   writefile $outformat $outfile $fieldlist

#  Remove input file information from Convsh's memory
   clearall
}