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Version 4.9.5 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 4.9.6 is a minor NCO release that contains a few new features and fixes. Unless the features/fixes listed below affect you, no need to upgrade this time.

New Features

1. ncclimo supports a new option --var_xtr to specify "extra variables" for the splitter to add to every generated timerseries. The splitter attempts to keep the generated timeseries as lean as possible and by default adds only the most useful ancillary variables, such as grid coordinates and CF-associated variable, to split timeseries. Previously, there was no way to add arbitrary variables, e.g., the CO2 volume mixing ratio, to a split timeseries. Now users can specify an arbitrary number of variables to includes in every split timeseries, e.g.,

   ncclimo --var=T,Q --var_xtr=co2vmr,FSDS ...
   

   In this example the splitter produces two output files because there are two primary variables (T,Q). Each timeseries also contain co2vmr and FSDS. Inclusion of other variables, e.g., area, depends on context and on other options
   http://nco.sf.net/nco.html#var_xtr
2. This version is forward-compatible with netCDF 4.8.0, which we know will contain some backward-incompatibile changes to filter behavior. Once netCDF 4.8.0 is released, if it becomes the default version of netCDF on your system, then you will likely need to upgrade to NCO 4.9.6 as previous versions may be incompatible with netCDF 4.8.0.
3. ncclimo now supports the -P (or --prc_typ) option instead of -m (or --mdl_nm) to determine the processing type. More importantly, ncclimo the -P option to ncremap internally, which simplifies some complex climo/regridding commands. For example, now it is possible to create regridded climatologies of output that requires sub-gridscale regridding with a single ncclimo command whereas previouly this required separate ncclimo and ncremap commands:

   ls *elm.h0* | ncclimo -P elm -s 1 -e 500 --map=map.nc
   ls *mpaso* | ncclimo -P mpaso -s 1 -e 500 --map=map.nc
   ls *mpassi* | ncclimo -P mpassi -s 1 -e 500 --map=map.nc

   The ncclimo -m mdl_nm option is still supported, and is required in some situations, e.g., when the processing type is 'elm' yet the history filenames use 'clm2' not 'elm'. In such mixed cases both -P and -m options may be necessary.
   http://nco.sf.net/nco.html#ncclimo
   http://dust.ess.uci.edu/smn/smn_nco_e3sm_202010.pptx
4. ncclimo and ncremap now support the large memory AMD (cmem) nodes on Cori when in MPI mode.

Additional details are available in the ChangeLog.