The netCDF operators NCO version 3.9.0 are ready.
http://dust.ess.uci.edu/nco (Homepage "mirror")
The version number jumped from 3.2.0 to 3.9.0 because of the addition
of functional (though limited) netCDF4 support.
NCO version 4.0 will be released after netCDF4.0 is final.
We want to avoid twisted versions like NCO3/netCDF4/HDF5/Chicago7.
Release 3.9.0 contains functional (though limited) netCDF4 support,
improved attribute copying, new documentation, an ncbo/ncdiff fix
for packed values, and better IRIX support.
Because the netCDF4 support description is extensive its description
appears at the end of this announcement.
The netCDF3 NCO improvements in 3.9.0 are:
A. netCDF4 support (see end of announcement).
B. ncks copying of variable and global metadata is configurable (-m, -M).
Formerly there was no way to append a variable from in.nc to out.nc
without bringing its metadata and all global metadata with it.
ncks -A in.nc out.nc # Append variable and global attributes
ncks -O in.nc out.nc # Copy variable and global attributes
ncks -v one in.nc out.nc # Copy variable and global attributes
ncks -O -v one in.nc out.nc # Copy variable and global attributes
ncks -A -v one in.nc out.nc # Append variable not global attributes
ncks -A -M -v one in.nc out.nc # Append variable not global attributes
ncks -O -M -v one in.nc out.nc # Copy variable not global attributes
ncks -O -m -v one in.nc out.nc # Copy global not variable attributes
ncks -O -M -m -v one in.nc out.nc # Copy data only, no attributes
ncks -A -m -v one in.nc out.nc # Append data only, no attributes
C. New Documentation:
Working with non-standard grids, e.g., 2D grids
D. ncks reports input file type (e.g., NC_FORMAT_CLASSIC,
NC_FORMAT_NETCDF4) as part of global metadata
E. Fix ncap2 .total() method to correctly handle missing_value's
F. ncap2 grows more powerful.
New demonstration scripts ~/nco/data/[bin_cnt.nco,psd_wrf.nco]
G. Fix bug where ncbo output differenced packed variables incorrectly
Thanks to Remik Ziemlinski for his excellent bug reports!
H. Pre-built, up-to-date, Debian Sid & Ubuntu binaries are available.
I. Pre-built, up-to-date, RPM packages are available.
Finally, what to expect with NCO support for netCDF4:
Support for netCDF4 features will be incremental, i.e.,
we'll add one netCDF4 feature at a time to NCO.
You must build NCO with netCDF4 to obtain this support.
There is no reason that we know of _not_ to build with netCDF4 now.
NCO support for netCDF4 features will be tracked and updated at
The main netCDF4 features that NCO currently supports are the new
atomic data types (ubyte, ushort, uint, int64, and uint64).
The eight-byte integer support may be especially helpful to you.
All NCO operators support these types, e.g., ncks prints them,
ncra averages them, and ncap2 scripts with them.
netCDF4-enabled NCO handles netCDF3 files without change.
In addition, it automagically handles netCDF4 (HDF) files:
If you feed NCO netCDF3 files, it produces netCDF3 output.
If you feed NCO netCDF4 files, it produces netCDF4 output.
Use the handy-dandy -4 switch to request netCDF4 output from
netCDF3 input, i.e., to convert netCDF3 to netCDF4.
Use appropriate caution while netCDF4 is beta software.
Problems with the netCDF4 and HDF libraries are still being fixed.
NCO support for netCDF4 atomic types is relatively untested.
Binary NCO distributions (RPMs and debs) still use netCDF3 for now.
If you want the netCDF4 support, you'll have to build NCO yourself:
You will need to specify the root of the netCDF4-beta1 installation
directory if you are also maintaining a pure netCDF3 installation.
Do this with the NETCDF4_ROOT variable.
Then use your preferred NCO build mechanism, e.g.,
export NETCDF4_ROOT=/usr/local/netcdf4 # Set netCDF4 location
cd ~/nco;./configure --enable-netcdf4 # Configure mechanism -or-
cd ~/nco/bld;./make NETCDF4=Y allinone # Old Makefile mechanism
Our short term goal is to track the netCDF4-beta releases, keep the
new netCDF4 atomic type support working, and iron out any problems.
Our long term goal is to utilize more of the extensive new netCDF4
feature set. The next major netCDF4 feature we are likely to utilize
is parallel I/O. We will enable this in the MPI netCDF operators.
Feedback is always welcome.
Charlie Zender, surname@xxxxxxx, Department of Earth System Science
3228 Croul Hall, UC Irvine, Irvine CA 92697-3100. (949) 824-2987 :)
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