Version 4.8.1 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 4.8.1 primarily contains enhancements to the vertical interpolation feature of
ncks. Two extrapolation
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
for north-to-south (n2s) Gaussian grid inferral and output, and
and improvements for finer-grained MPI parallelism.
ncremap/ncksnow 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.nchttp://nco.sf.net/nco.html#n2s
ncremapnow 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.nchttp://nco.sf.net/nco.html#vrt_fl
ncclimonow 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
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.nchttp://nco.sf.net/nco.html#vrt_xtr
ncremapESMF extrapolation options
xtr_xpnhave been renamed
esmf_xpn, respectively. This was done to make them easier to find and to segregate regridder-specific from regridder-generic options.
ncremapaccepts 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
ncremapMWF mode now only generates TempestRemap maps when one or both input grids are Exodus-format (and end with a
.gsuffix). This was done to keep ERWG and TR map-generation from being interdependent in case a grid-pair breaks one or the other.
Additional details are available in the ChangeLog.