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Comment: Confirmed: useful for grib to netCDF conversion

module load cdo

  • To convert to regular lat/lon
    cdo -R remapcon,r1600x800 -setgridtype,regular h14_2019053000.grib h14_2019053000_r.grib
  • Then convert the file from grib to netcdf:

cdo -f nc copy h14_2019053000_r.grib

  • Then extract the Italian domain from the global netcdf file (lon0=5, lon1=19, lat0=36, lat1=48):

cdo -sellonlatbox,5,19,36,48

#Note that the size of the file is vastly reduced ( ~ 25 mb, ~ 70 kb)!

  • Size of netCDF files can be further reduced by compression e.g.
    cdo -f nc4c -z zip_6 copy h14_2019053000_r.grib
  • To convert multiple files from grib to netCDF, you can loop over all the files in the directory and apply the commands above e.g.

for file in *.grib; do cdo -R remapcon,r1600x800 -setgridtype,regular "$file" "$file".reg; done #To convert to regular grid
for file in *.reg; do cdo -f nc copy "$file" "$file".nc; done #To convert regular grib files to netCDF 

for file in *.nc; do cdo -sellonlatbox,5,19,36,48 "$file" "$file"_italy; done #To extract Italian domain

  • A time series file can be created by stacking multiple daily netcdf files, for example using cdo mergetime:

cdo mergetime h27*.nc