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Version 4.7.0 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 4.7.0 adds spit and polish throughout the toolkit. Nothing major stands out, except perhaps for easy access to compression algorithms in ncclimo and ncremap.

New Features

1. ncclimo and ncremap accept fl_fmt options for output file format. The option behaves the same as it does for other operators:

   ncclimo [-3 -4 -5 -6 -7] ...
   ncremap [-3 -4 -5 -6 -7] ...
   ncclimo --fl_fmt=netcdf4 ...
   ncremap --fl_fmt=cdf5 ...

   http://nco.sf.net/nco.html#fl_fmt
   http://nco.sf.net/nco.html#autoconversion
2. ncclimo and ncremap accept the dfl_lvl option for compression. The value of dfl_lvl is an integer fro 0..9 that specifies the DEFLATE (= Lempel-Ziv + Huffman) compression level for netCDF4. The option behaves the same as it does for other operators:

   ncclimo --dfl_lvl=3 ...
   ncremap --dfl_lvl=3 ...
   ncclimo -L 3 ...
   ncremap -L 3 ...

   http://nco.sf.net/nco.html#deflate
3. ncclimo accepts the ppc option for Precision-Preserving Compression. Other operators allow multiple, per-variable PPC specification. ncclimo allows only one PPC option, equivalent to specifying --ppc default=<val> with the compiled operators. NB: regridding does not yet accept PPC.

   ncclimo --ppc=3 ...

   http://nco.sf.net/nco.html#ppc
   http://nco.sf.net/nco.html#bitgrooming
4. ncrename is now quiet by default, like all other operators. The old summary line that tallied the numbers of things renamed can still be seen by invoking ncrename with -D 1.
   http://nco.sf.net#ncrename
5. CMake: Pedro Vicente contributed a CMake build-engine in 4.6.9. The CMake engine now correctly links ncap2 to intrinsic math functions like erf(), gamma(), ... Please give us feedback on any wrinkles in the CMake build. To build with CMake and install in /usr/local:

   cd nco/cmake
   cmake .. -DCMAKE_INSTALL_PREFIX=/usr/local
   make
   sudo make install

   Additional examples in cmake/build.bat
   http://nco.sf.net#bld
6. The automatic CDF5 bug checker in 4.6.9 has been turned-off. It produced too much distracting output in workflows affected by the CDF5 bug. To activate this check, build NCO with, e.g.,

   CPPFLAGS='-DNCO_CDF5_BUG_CHK' ./configure ...

   The checker itself has been improved so that, when turned on, operators are now quiet when sniffing CDF5 files for corruption, until they detect a "large" (> 4 GB) variable. In 4.6.9 the sniffing algorithm was noisier, and printed an INFO upon closing any CDF5 file.
   http://nco.sf.net#bug_cdf5

Additional details are available in the ChangeLog.