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Version 5.3.2 of the netCDF Operators (NCO) has been released. NCO is an Open Source package that consists of a dozen standalone, command-line programs that take netCDF files as input, then operate (e.g., derive new data, average, print, hyperslab, manipulate metadata) and output the results to screen or files in text, binary, or netCDF formats.

The NCO project is coordinated by Professor Charlie Zender of the Department of Earth System Science, University of California, Irvine. More information about the project, along with binary and source downloads, are available on the SourceForge project page.

From the release message:

Version 5.3.2 mainly adds features and fixes to ncremap and quantization. Support for vertical interpolation of ECMWF IFS, and CAMS-format hybrid sigma-pressure vertical coordinate datasets has been improved. And the output is more CF-compliant. All arithmetic operators are once again able to use NCO quantization algorithms on variables in non-root groups. Skip this release if these changes do not interest you.

New Features

1. ncremap will vertically interpolate a broader array of ECMWF IFS and CAMS-format hybrid sigma-pressure vertical coordinate datasets. Recent NCO versions required the log of the surface pressure to be in the template vertical coordinate file, rather than in the main dataset. Now the (log of) surface pressure can be either in the source dataset or the vertical grid file. Previous versions requires the lnsp variable to contain a dimension named lev_2 (as in IFS data). Now the regridder also accomodates CAMS-format data that does not contain the lev_2 dimension.

   ncremap --ps_nm=lnsp --vrt_fl=era5.nc cams_in.nc cams_out.nc

   http://nco.sf.net/nco.html#ifs
   http://nco.sf.net/nco.html#vrt
2. ncremap's vertical interpolator now attaches CF metadata (standard_name), units, and long_name attributes to output files stored on hybrid sigma-pressure vertical coordinate grids, e.g.,

   double P0 ;
       P0:long_name = "Reference pressure" ;
       P0:standard_name = "reference_air_pressure_for_atmosphere_vertical_coordinate" ;
       P0:units = "Pa" ;
    double hybm(nhym) ;
       hybm:long_name = "hybrid B coefficient at layer midpoints" ;
       hybm:units = "1" ;
       hybm:standard_name = "atmosphere_hybrid_sigma_pressure_coordinate" ;
   

3. ncremap and ncclimo previously prevented refused to overwrite input files with the same name as output files. However, this safety feature failed to detect when input and output filenames were symbolic links to the same file. Now ncremap and ncclimo refuse to overwrite input files that are the same inode/device as output files.
4. ncremap and ncclimo previously defaulted to using PBS "mpi_run -n nd_nbr" to manage MPI-mode climatologies and regridding. Now ncremap and ncclimo previously default to using SLURM "srun -n nd_nbr". This makes supporting MPI-mode on unknown (not in the internal database of ncremap/ncclimo) machines more likely to work on SLURM, which has become increasingly popular (at least at DOE).
   http://nco.sf.net/nco.html#mpi

Additional details are available in the ChangeLog.