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.

Version 5.3.4 contains of bevy of minor features that improve NCO in many different areas. These range from reduced monotonicity WARNINGs from ncrcat, to an easy new method for all operators to remove global attributes, to bulletproofing ncclimo to work as intended with instantaneous input, to new urban landunit diagnostics in ncks.

Version 5.3.3 adds IEEE floating-point exception testing to ncks. All operators include corner-case quantization fixes for strange numbers (-0.0, NaN) that are also now in the netCDF-C Library. ncclimo now only tries to create regional timeseries statistics on variables that are single-level horizontal lat/lon/ncol fields. ncremap supports interpolation of pure-pressure to hybrid sigma-pressure coordinates with distinct source and destination surface pressure fields. And ncrename adds some words of caution. Skip this release if these changes do not interest you.

Did you realize that the first public release of ncks was May 2, 1995?
https://www.unidata.ucar.edu/mailing_lists/archives/netcdfgroup/1995/msg00069.html
Happy 30th birthday ncks!!!

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.

Version 5.3.1 adds features and fixes to ncremap and ncclimo. The new autoconversion feature allows these scripts to automagically convert netCDF4 string variables to netCDF3 character arrays. The improved treatment of fixed time dimensions allows ncclimo to work with raw MERRA2 files. Together these improvements make possible regridding and vertical interpolation of the new formatting of Copernicus Data Store (CDS) files used for, e.g., ERA5. Skip this release if these changes do not interest you.

Version 5.3.0 significantly improves the unpacking of ELM/CLM/CTSM history and restart datasets, and seems complete in this regard. ncrcat has more friendly behavior when appending, and ncclimo now outputs more metrics (such as valid area per gridcell) when in regional statistics mode. This release many be skipped if these changes do not interest you.

Version 5.2.9 significantly improves the unpacking of ELM/CLM/CTSM history and restart datasets. ncclimo and ncremap benefit from a few updates and fixes. This release many be skipped if these changes do not interest you.

Version 5.2.8 mostly contains features and fixes for regridding and climatology generation. Climatologies now allow the choice between two statistics (sums and means) to output as regional/global timeseries. The regridder fixes corner case behavior when the sub-gridscale (SGS) fraction is a missing value (as in ELM/CLM). Many improvements to the robustness and helpfulness of WARNINGs and ERRORs are included. Upgrades are encouraged for everyone who uses the regridder on ELM/CLM/CTSM datasets.

Version 5.2.7 contains updates to quantization metadata, enhanced grid area diagnostics for check_map, and bug-fixes for ncremap.

Version 5.2.6 contains a one-line bugfix to ncremap in 5.2.5. Unfortunately that horse had already escaped the barn. There is nothing else new in 5.2.6, so the release notes below repeat those for 5.2.5 so people can get a quick summary of new features since the previous widely distributed version, 5.2.4.

Version 5.2.6 fully implements the draft CF lossy metadata convention for all NCO internal quantization algorithms. It also improves ncclimo diagnostics and adds a new invocation synonym (--qnt) for quantization, and outputs a maximum_relative_error statistic where possible. ncclimo/ncremap add support for MPAS-Atmosphere datasets, and ncclimo supports excluding variable lists in timeseries mode. Skip this release if these changes are not important to you.