$Header$ -*-text-*- netCDF Operators NCO version 5.3.8 mends fences http://nco.sf.net (Homepage, Mailing lists, Help) http://github.com/nco/nco (Source Code, Issues, Releases) What's new? Version 5.3.8 contains fixes to ncclimo problems introduced with 5.3.7. The ncclimo "flexible-months" feature suffered from incorrect behavior for some inputs, and introduced a regression in seasonal filenames. The only new feature is that ncclimo now supports generating climos from high-frequency input data that are instantaneous (not mean) values. Documentation now reflects the new CF Convention Homepage URL. Users who upgraded to 5.3.7 should upgrade to 5.3.8, and 5.3.7 should not be used anymore. Enjoy, Charlie NEW FEATURES (full details always in ChangeLog): A. ncclimo now supports generating climos from high-frequency input data that are instantaneous (not mean) values. This mainly means that that the time bounds and climatology bounds variables now use the instantaneous time from the original time coordinate input, rather than the average value of the time coordinate input. Thanks to Jill Zhang (LLNL) for feature testing and feedback. http://nco.sf.net/nco.html#ncclimo B. All links to documentation now point to the newish CF Homepage at https://cf-convention.github.io/cf-conventions. BUG FIXES: A. ncclimo flexible months mode introduced in 5.3.7 sometimes generated read datasets in the wrong order. Thanks to Jill Zhang (LLNL) for identifying this issue. http://nco.sf.net/nco.html#ncclimo B. ncclimo flexible months mode introduced in 5.3.7 sometimes caused input years with leading zeros to be interpreted as octal numbers and therefore generate inaccurate filenames. Thanks to Xylar Asay-Davis (ANL) for reporting this issue. http://nco.sf.net/nco.html#ncclimo Full release statement at http://nco.sf.net/ANNOUNCE KNOWN PROBLEMS DUE TO NCO: This section of ANNOUNCE reports and reminds users of the existence and severity of known, not yet fixed, problems. These problems occur with NCO 5.3.8 built/tested under MacOS 26.3 with netCDF 4.10.1-development on HDF5 2.1.1 and with Linux FC42 with netCDF 4.9.2 on HDF5 1.14.4. A. NOT YET FIXED (NCO problem) Correctly read arrays of NC_STRING with embedded delimiters in ncatted arguments Demonstration: ncatted -D 5 -O -a new_string_att,att_var,c,sng,"list","of","str,ings" ~/nco/data/in_4.nc ~/foo.nc ncks -m -C -v att_var ~/foo.nc 20130724: Verified problem still exists TODO nco1102 Cause: NCO parsing of ncatted arguments is not sophisticated enough to handle arrays of NC_STRINGS with embedded delimiters. B. NOT YET FIXED (NCO problem?) ncra/ncrcat (not ncks) hyperslabbing can fail on variables with multiple record dimensions Demonstration: ncrcat -O -d time,0 ~/nco/data/mrd.nc ~/foo.nc 20140826: Verified problem still exists 20140619: Problem reported by rmla Cause: Unsure. Maybe ncra.c loop structure not amenable to MRD? Workaround: Convert to fixed dimensions then hyperslab KNOWN PROBLEMS DUE TO BASE LIBRARIES/PROTOCOLS: A. NOT YET FIXED (netCDF4 or HDF5 problem?) Specifying strided hyperslab on large netCDF4 datasets leads to slowdown or failure with recent netCDF versions. Demonstration with NCO <= 4.4.5: time ncks -O -d time,0,,12 ~/ET_2000-01_2001-12.nc ~/foo.nc Demonstration with NCL: time ncl < ~/nco/data/ncl.ncl 20140718: Problem reported by Parker Norton 20140826: Verified problem still exists 20140930: Finish NCO workaround for problem 20190201: Possibly this problem was fixed in netCDF 4.6.2 by https://github.com/Unidata/netcdf-c/pull/1001 Cause: Slow algorithm in nc_var_gets()? Workaround #1: Use NCO 4.4.6 or later (avoids nc_var_gets()) Workaround #2: Convert file to netCDF3 first, then use stride Workaround #3: Compile NCO with netCDF >= 4.6.2 B. NOT YET FIXED (netCDF4 library bug) Simultaneously renaming multiple dimensions in netCDF4 file can corrupt output Demonstration: ncrename -O -d lev,z -d lat,y -d lon,x ~/nco/data/in_grp.nc ~/foo.nc # Completes but produces unreadable file foo.nc ncks -v one ~/foo.nc 20150922: Confirmed problem reported by Isabelle Dast, reported to Unidata 20150924: Unidata confirmed problem 20160212: Verified problem still exists in netCDF library 20160512: Ditto 20161028: Verified problem still exists with netCDF 4.4.1 20170323: Verified problem still exists with netCDF 4.4.2-development 20170323: https://github.com/Unidata/netcdf-c/issues/381 20171102: Verified problem still exists with netCDF 4.5.1-development 20171107: https://github.com/Unidata/netcdf-c/issues/597 20190202: Progress has recently been made in netCDF 4.6.3-development More details: http://nco.sf.net/nco.html#ncrename_crd C. NOT YET FIXED (would require DAP protocol change?) Unable to retrieve contents of variables including period '.' in name Periods are legal characters in netCDF variable names. Metadata are returned successfully, data are not. DAP non-transparency: Works locally, fails through DAP server. Demonstration: ncks -O -C -D 3 -v var_nm.dot -p http://thredds-test.ucar.edu/thredds/dodsC/testdods in.nc # Fails to find variable 20130724: Verified problem still exists. Stopped testing because inclusion of var_nm.dot broke all test scripts. NB: Hard to fix since DAP interprets '.' as structure delimiter in HTTP query string. Bug tracking: https://www.unidata.ucar.edu/jira/browse/NCF-47 D. NOT YET FIXED (would require DAP protocol change) Correctly read scalar characters over DAP. DAP non-transparency: Works locally, fails through DAP server. Problem, IMHO, is with DAP definition/protocol Demonstration: ncks -O -D 1 -H -C -m --md5_dgs -v md5_a -p http://thredds-test.ucar.edu/thredds/dodsC/testdods in.nc 20120801: Verified problem still exists Bug report not filed Cause: DAP translates scalar characters into 64-element (this dimension is user-configurable, but still...), NUL-terminated strings so MD5 agreement fails "Sticky" reminders: A. Reminder that NCO works on most HDF4 and HDF5 datasets, e.g., HDF4: AMSR MERRA MODIS ... HDF5: GLAS ICESat Mabel SBUV ... HDF-EOS5: AURA HIRDLS OMI ... B. Pre-built executables for many OS's at: http://nco.sf.net#bnr