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Version 5.1.4 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 5.1.4 introduces vertical interpolation for datasets stored on depth/height grids, such as ocean data. The interpolation works on all datasets tested with vertical levels that are either horizontally varying (e.g., MPAS-Ocean, POP, MOM) or uniform (many observational datasets including ARGO, SOSE, WOA18). The algorithms play well with horizontally varying bathymetry. This release also fixes a vexing issue that can occur with certain compilers on AMD hardware. This release can be skipped if these regridding features are not useful to you.

New Features

1. ncremap can now vertically interpolate files/fields stored on depth/height-based vertical grids. The capability is analogous to the existing ncremap capability of interpolating data on pure-pressure or hybrid sigma/pressure vertical grids (all four combinations work):

   ncremap --vrt_out=vrt_out.nc in.nc out.nc
   ncremap --vrt_in=vrt_in.nc --vrt_in=vrt_out.nc in.nc out.nc
   ncremap -P mpas --vrt_out=vrt.nc --map=map.nc in.nc out.nc
   ncremap --vrt_out=sose.nc mpas.nc out.nc
   ncremap --vrt_out=mpas.nc sose.nc out.nc
   ncremap --vrt_out=woa18.nc mpas.nc out.nc
   ncremap --vrt_out=mpas.nc woa18.nc out.nc
   ncremap --vrt_out=argo.nc mpas.nc out.nc
   ncremap --vrt_out=mpas.nc argo.nc out.nc
   

   The depth/height grid may be positive upwards or downwards.
   http://nco.sf.net/nco.html#ncremap
   http://nco.sf.net/nco.html#vrt_out
   This is the first release of vertical interpolation for ocean data, and we expect some rough edges. Please let us know what features you want added or fixed.
2. Operators now silently avoid attempting to compress variable-length datatypes, i.e., variables of type NC_STRING or NC_VLEN. This is because neither netCDF nor HDF allow compression of these types. Previously, attempting to compress these types would trigger a netCDF error. Now the request will be silently ignored and program will proceed as expected in all other ways.
3. The software stack upon which the Anaconda NCO package depends has been future-proofed. Specifically the feedstocks for the Antlr2 and NCO packages have been updated to enable building conda-based packages on newer architectures such as linux-ppc64le, osx-arm64, and linux-aarch64.

Additional details are available in the ChangeLog.