NetCDF operators (NCO) version 5.3.5

Version 5.3.5 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 5.3.5 contains mostly speed, robustness, and documentation improvements for the regridder. The ability to select alternate executable and library paths for testing snapshots is also improved. Skip this release if these changes do not interest you.

New Features

1. The map checker (ncks --chk_map) is more robust and clear in its reports. For robustness, the checker now ensures that all row/col indices are valid before attempting to use them. Illegal values are summarized and printed. The regridder also does now. Illegal values previously caused the checker and regridder to die with baffling core-dumps. Conservation and Consistency metrics now include plain-language definitions.
2. The ncremap tutorial on the E3SM Confluence page https://e3sm.atlassian.net/wiki/spaces/DOC/pages/edit-v2/754286611 now contains extensive documentation on how to exploit the three types of parallelism (node-, workflow-, and thread-level) supported by ncremap. New examples show the scaling of performance with OpenMP threads for regridding and for weight-generation.
3. The --npo (NCO Path Override) option allows other users to easily test bleeding-edge features present in development versions of NCO in Charlie Zender's home directories at DOE HPC centers. This feature has been updated to work with the latest paths on Andes, Chrysalis, and Perlmutter.
   http://nco.sf.net/nco.html#npo
   http://nco.sf.net/nco.html#nco_path_override
4. All operators that accept -v as the option to indicate a list of variables now also accept --var_lst. This makes the binary executables consistent with ncremap/ncclimo.
   http://nco.sf.net/nco.html#var_lst

5. plev can now be a full path name. Previously the pressure levels for vertical interpolation were always contained in the destination vertical grid file. However, pure pressure vertical grids require only the plev variable so requiring that variable to be in its own file was unnecessary. Now the 'plev' variable can be specified as a full path name, e.g., --vrt=/home/bar/data.nc/plev. Here the variable 'plev' will be searched for in the file /home/bar/data.nc. This is similar to the way the surface pressure ps for hybrid sigma-pressure coordinates can be a full-pathname. This is the first step to supporting 3D pressure fields as target grids.

   ncremap --vrt=/path/to/file.nc/plev in.nc out.nc

   http://nco.sf.net/nco.html#vrt

Additional details are available in the ChangeLog.