[netcdfgroup] Les netCDF Operators NCO version 4.8.1 sont nés

• To: NCO Announce Mail List <nco-announce@xxxxxxxxxxxxxxxxxxxxx>, netcdfgroup@xxxxxxxxxxxxxxxx
• Subject: [netcdfgroup] Les netCDF Operators NCO version 4.8.1 sont nés
• From: Charlie Zender <zender@xxxxxxx>
• Date: Mon, 1 Jul 2019 18:51:19 +0200

The netCDF Operators NCO version 4.8.1 are born.

http://nco.sf.net (Homepage, Mailing lists, Help)
http://github.com/nco (Source Code, Issues, Releases, Developers)

What's new?

Version 4.8.1 primarily contains enhancements to the vertical
interpolation feature of ncremap, ncclimo, and ncks. Two extrapolation
options are now supported (nearest neighbor and missing value), and
the entire procedure now works with the ECMWF IFS hybrid sigma
pressure grid as input. Other changes include better support for
north-to-south (n2s) Gaussian grid inferral and output, and ncclimo
updates and improvements for finer-grained MPI parallelism.
See below for full details.

Work on NCO 4.8.2 has commenced and will expose more powerful options
for vertical interpolation and, hopefully, the debut of the NCO
weight-generator for regridding.

Work on NCO 5.0.0 has commenced "under the hood". The key leap in that
release will be support for netCDF4 user-defined types. Printing of
netCDF4 user-defined types ENUM and VLEN is ready now (though
unsupported) with the --udt flag. 5.0.0 will contain the finished
version of that, and progress on native weight generation by ncremap.

Enjoy,
Charlie

NEW FEATURES (full details always in ChangeLog):

A. ncremap/ncks now always creates/infers north-to-south grids with
   polygons in counter-clockwise (CCW) orientation. Formerly, polygons in
   south-to-north grids had CCW orientation while those in north-to-south
   grids had CW orientation.
   ncremap -G latlon=1280,2560#lat_typ=gss#lat_drc=n2s -g $HOME/grd_n2s.nc
   ncremap -d ecmwf_ifs.nc -g grd_n2s.nc
   http://nco.sf.net/nco.html#n2s
   http://nco.sf.net/nco.html#ncremap

B. ncremap now vertically interpolates data from ECMWF IFS hybrid
   vertical grid format to CAM/E3SM hybrid format and to pure-pressure
   format. ECMWF archives and serves IFS data in a hybrid
   sigma-pressure grid format significantly different from CAM/E3SM.
   ECMWF supplies lnsp (log surface pressure) not PS (surface
   pressure). There are numerous other metadata differences.
   NCO now automatically takes care of these.
   ncremap --vrt=vrt_hyb_L72.nc ecmwf_ifs_f640L137.nc out.nc
   http://nco.sf.net/nco.html#vrt_fl
   http://nco.sf.net/nco.html#ncremap

C. ncks, ncremap, and ncclimo now support two different extrapolation
   algorithms for vertical regridding. The original and default
   extrapolation algorithm uses the nearest valid neighbor.
   This is now explicitly selectable with --vrt_xtr=nrs_ngh.
   The second supported algorithm extrapolates to missing values.
   This is now explicitly selectable with --vrt_xtr=mss_val.
   ncremap --vrt=vrt.nc --vrt_xtr=mss_val in.nc out.nc
   ncremap --vrt=vrt.nc --vrt_xtr=nrg_ngh in.nc out.nc
   ncclimo --vrt=vrt.nc --vrt_xtr=mss_val -i drc_raw -O drc_rgr
   ncks --vrt=vrt.nc --rgr vrt_xtr=mss_val in.nc out.nc
   http://nco.sf.net/nco.html#vrt_xtr
   http://nco.sf.net/nco.html#ncremap

D. The former ncremap ESMF extrapolation options xtr_nsp, xtr_typ, and
   xtr_xpn have been renamed xtr_nsp, xtr_typ, and esmf_xpn,
   respectively. This was done to make them easier to find and to
   segregate regridder-specific from regridder-generic options.
   http://nco.sf.net/nco.html#esmf_typ
   http://nco.sf.net/nco.html#ncremap

E. ncremap accepts a new option, --msh_fl=msh.nc, to specify the name
   of the intersection mesh-file. This option only works with the
   TempestRemap and NCO weight-generators. (The NCO weight-generator
   is still in development and is not yet supported. Interested beta
   testers can access it with --alg_typ=nco).

F. ncremap MWF mode now only generates TempestRemap maps when one or
   both input grids are Exodus-format (and end with a .g suffix).
   This was done to keep ERWG and TR map-generation from being
   interdependent in case a grid-pair breaks one or the other.

BUG FIXES:

A. ncremap now infers north-to-south Gaussian grids correctly.
   Previously such grids, like ECMWF IFS grids, failed to converge
   in the Newton-Raphson iteration for latitude interfaces.
   ncremap -d ecmwf_ifs.nc -g grd_n2s.nc
   The solution is to upgrade to 4.8.1, and the workaround is to use
   ncpdq to reorder the grids from n2s to s2n.
   Thanks to Wuyin Lin of BNL for highlighting this issue.
   http://nco.sf.net/nco.html#n2s
   http://nco.sf.net/nco.html#gss

B. North-to-south grids are now output in counterclockwise order.
   Previously s2n and n2s grids were output in CCW and CW order,
   respectively. Now all grids are CCW.
   Thanks to Wuyin Lin of BNL for highlighting this issue.
   http://nco.sf.net/nco.html#n2s

C. ncap2 correctly overwrites output-files in single-file mode.
   4.8.0 introduced the single-file feature where ncap2 does
   not need two file arguments, but instead can construct the
   output file purely from scratch. In the case where an output
   file of the same name already existed, ncap2 would fail to
   overwrite it when given the -O argument:
   ncap2 -O -s 'one=1' ~/foo.nc # now works
   ncap2    -s 'one=1' ~/foo.nc # always worked
   http://nco.sf.net/nco.html#ncap2

Full release statement at http://nco.sf.net/ANNOUNCE

--
Charlie Zender, Earth System Sci. & Computer Sci.
University of California, Irvine 949-891-2429 )'(