netCDF Operators NCO version 5.1.5 ascend the Silicon Throne
http://nco.sf.net (Homepage, Mailing lists, Help)
http://github.com/nc/ncoo (Source Code, Issues, Releases)
What's new?
Version 5.1.5 polishes the new vertical interpolation capabilities
introduced in 5.1.3 and 5.1.4, improves the safety NCZarr operations,
and fixes minor ncremap bugs. This release can be skipped if these
regridding and NCZarr features are not useful to you.
Work on NCO 5.1.6 has commenced and aims to add support for Zarr S3
stores and to polish support for new codecs.
Enjoy,
Charlie
NEW FEATURES (full details always in ChangeLog):
A. ncremap now behaves more sensibly when vertically interpolating
MPAS-Ocean files/fields. Previously, users had to explicitly add
the multidimensional auxiliary depth coordinate (often
timeMonthly_avg_zMid) to the subsetted list of variables whenever
the subset list option (-v var1,var2...) was used. This is because
most MPAS datasets do not adhere to the CF "coordinates" convention,
and NCO has no way of knowing which auxiliary coordinates contain
the depth field. Now ncremap uses the -P mpasocean option to trigger
a search for the zMid coordinate in the input file. If found, ncremap
automatically adds it to the subset as appropriate.
ncremap -P mpas --vrt_out=vrt.nc --map=map.nc in.nc out.nc
http://nco.sf.net/nco.html#ncremap
http://nco.sf.net/nco.html#vrt_out
B. ncremap has a --ps_rtn (--retain_surface_pressure) switch
to facilitate "round-trip" vertical interpolation such as
hybrid->pressure->hybrid. By default ncremap excludes the surface
pressure field from the output after hybrid->pressure interpolation.
The --ps_rtn switch (which takes no argument) instructs the regridder
to retain the surface pressure field after hybrid->pressure
interpolation. This field is then available for subsequent
interpolation back to a hybrid vertical coordinate.
ncremap --ps_rtn --ps_nm=ps --vrt_out=ncep.nc in.nc out_ncep.nc
ncremap --ps_rtn -v T,Q,U,PS --vrt_out=ncep.nc in.nc out_ncep.nc
ncremap --vrt_out=hybrid.nc out_ncep.nc out_hybrid.nc
http://nco.sf.net/nco.html#ps_rtn
C. NCO is now more careful about overwriting existing directories
and files with NCZarr stores. Previously NCO would overwrite any
directory or file that the netCDF library could successfully open.
However, netCDF library versions 4.8.0->4.9.1 "succeed" in opening
non-NCZarr stores. Hence additional precautions are necessary to
avoid unintentionally overwriting non-NCZarr paths with NCZarr
stores. For example,
ncks in_zarr4.nc file://${HOME}/ncz_dnd/foo#mode=nczarr,file
now overwrites "foo" only if it is already an NCZarr store.
Previously foo would be overwritten if it already existed yet was
not a valid NCZarr store. Thanks to Dennis Heimbigner of Unidata
for discussing this behavior.
D. NCO improves handling of output from the DOE EAMxx model
in two ways. First, NCO now treats this model output as
CF-compliant. This causes NCO to implement special conventions such as
carrying multi-dimensional auxiliary coordinate variables when
subsetting. Second, ncremap automatically permutes EAMxx datasets
that have been interpolated to pressure levels to have the correct
dimension ordering (horizontal dimension as most-rapidly-varying)
prior to horizontal regridding. Thanks to Chris Golaz (LLNL) prompting
these features.
BUG FIXES:
A. ncrcat versions 4.8.0--5.1.4 could erroneously add a cell_methods
attribute to variables it processed. This behavior has been
eliminated. ncra still adds the attribute by default. The workaround
is to invoke ncrcat with the --no_cll_mth flag. The solution is to
upgrade. Thanks to Brian Vanderwende (NCAR) for reporting this.
B. Recent versions of ncremap incorrectly parsed the
--preserve_statistic (--prs_stt) option. The option was effectively
ignored. This has been fixed. The workaround is to explicitly invoke
the --rnr_thr=0.0 option. The solution is to upgrade. These two
commands now produce the same result, use whichever you prefer:
ncremap --rnr_thr=0.0 --map=map.nc in.nc out.nc
ncremap --prs_stt=local_mean --map=map.nc in.nc out.nc
C. ncremap version 5.1.4 incorrectly handles the name of the output
coordinate for vertical interpolation to pure-pressure surfaces.
Instead of naming the coordinate 'plev', or whatever is in the vrt_out
file, or what was specfified by the --plev_nm_out option, it just
named the coordinate (variable+dimension) 'lev'. These have all been
fixed. There is no workaround, and the solution is to upgrade.
Thanks to Jill Zhang (LLNL) and Ben Hillman (SNL) for reporting this
issue.
D. Vertical interpolation with ncremap now successfully handles
missing values interior to the vertical domain. This is useful
to interpolate from pure pressure and depth coordinates where
bathymetry and orography are masked, to terrain following sigma
coordinates where bathymetry and orography are outside the domain.
Previously ncremap would allow missing values inside the vertical
domain to contaminate the interpolated values. There is no
workaround. The solution is to upgrade. Thanks to Peter Caldwell
(LLNL) for reporting this issue and beta-testing the fix.
Full release statement at http://nco.sf.net/ANNOUNCE
--
Charlie Zender, Earth System Sci. & Computer Sci.
University of California, Irvine 949-891-2429 )'(
