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Version 4.9.7 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 4.9.7 is a minor NCO release that contains a few new features and fixes. Most notable are support for inferring SCRIP grids from MPAS restart files, initial support for the CCR in ncap2, and ncclimo bug-fixes for high frequency data and for the glb_avg option. Unless the features/fixes listed below affect you, no need to upgrade this time.

New Features

1. ncremap can now infer SCRIP grids from MPAS restart files. This is useful when users lack access to the gridfiles their model used. This can easily happen when running standalone MPAS simulations that use non-scientifically validated grids. Previously inferring MPAS grids produce incomplete (no corners) and erroneous (degrees not radians in metadata) grids. Now the inferred grids are complete, consistent, and BFB with the original grids used in the MPAS simulation.

   ncremap -d ~/restart.2001-01-01_00.00.00.nc -g QU120_zach.nc
   

   http://nco.sf.net/nco.html#ncremap
   http://nco.sf.net/nco.html#infer
2. ncremap and ncclimo have been updated to work in MPI mode on the new DOE machines Andes (ORNL) and Chrysalis (ANL LCRC).
   
   http://nco.sf.net/nco.html#par_typ
3. NCO can be built to leverage the Communinty Codec Repository. The CCR is currently supports two lossless compression filters (BZip2, Zstandard) and one lossy quantization filter (BitGroom). More importantly, the CCR is extensible and provides the C/Fortran API for defining alternative (non-DEFLATE) compression using a netCDF-like API at file creation time. The NCO ncap2 operator will now access these filters for rewriting variables in existing files:

   ./configure --enable-ccr; make; make install # Build NCO with CCR
   ncap2 -O -7 --ccr=Zstd -L 3 -s 'two=one+one' in.nc out.nc
   ncap2 -O -7 --ccr=BitGroom -L 3 -s 'two=one+one' in.nc out.nc
   ncks -C --hdn -v three_dmn_rec_var out.nc # Examine data

   http://github.com/ccr/ccr
   
   CCR capabilities, and NCO support for them, will expand in 2021. Thanks to Ed Hartnett of NOAA (and netCDF4/PIO fame) for partnering on the CCR! See our poster on the CCR 1.1 release at AMS.

Additional details are available in the ChangeLog.