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Based on extensive evaluation of AMWG, UV-CDAT, and NCO codes for generating climatology files (see here), we have determined that NCO provides the most correct answers, has the best metadata, and is fastest. Until UV-CDAT bests NCO in these measures we advocate using the NCO tool for creating climatologies.
We have created a new The NCO command, ncclimo (formerly climo_nco.sh) that will generate and regrid all climatology files . This (NB: from model or measurement monthly input files). The primary documentation is here. This presentation, given at the Albuquerque workshop on 20151104, conveys much of the information presented below, and some newer information, in a more graphical format. Currently (20160422) the major difference between the commands is that ncclimo fully implements the CF climatology-bounds and climatological statistics (for cell_methods) conventions, whereas climo_nco.sh does not.
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Use ncclimo if possible. It requires and comes with NCO version 4.6.0 and later. Its predecessor climo_nco.sh (which is deprecated) requires NCO version 4.5.2 or later. The newest versions of NCO are installed on rhea/titan.ccs.ornl.gov at ORNL, pileus.ornl.gov (CADES at ORNL), cooley/mira.alcf.anl.gov at ANL, cori/edison.nersc.gov (NERSC), aims4.llnl.gov (LLNL), roger.ncsa.illinois.edu (NCSA), and yellowstone.ucar.edu (NCAR). The ncclimo and ncremap scripts are hard-coded to find these the latest versions automatically, and do not require any module or path changes. For other machines check that the default NCO is recent enough (try "module load nco", then "ncks --version"To use other (besides the ncclimo and ncremap scripts) NCO executables from the command-line or from your own scripts may require loading modules. This is site-specific and not under my (CZ's) control. At OLCF, for example, "module load gcc" helps to run NCO from the command-line or scripts. For other machines check that the default NCO is recent enough (try "module load nco", then "ncks --version") or use developers' executables/libraries (in ~zender/[bin,lib] on all machines). Or follow Follow these directions (on the NCO homepage) to install on your own machines/directories.
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A complete description of all available flags options is given in comments embedded in ncclimo, in the NCO documentation here, and for convenience here is a in summary form:
-s: start year (example: 1980). a: type of DJF average. Either -a scd (default) or -a sdd. scd is seasonally continuous December. The first month used will be Dec of the year year before the the start year you specify (example Dec 1979 to allow for contiguous DJF climos). If "-a sdd" is specified, the with -s. sdd is seasonally discontinuous December. The first month used will be Jan of the specified start year.
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-a scd (default) : seasonally continuous December. The first month used will be Dec of the year before the start year you specify with -s
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-o: directory where computed native grid climo files will be placed. Regridded climos will also be placed here unless a separate directory for them is specified with -O (NB: capital "O")
-O: directory where regridded climo files will be placed.
-c: caseid, i.e., simulation name. For input files like famipc5_ne30_v0.3_00001.cam.h0.1980-01.nc, specify "-c famipc5_ne30_v0.3_00001". The ".cam." and ".h0." bits are added to the filenames internally by default, and can be modified via the "-m mdl_nm" and "-h hst_nm" switches if needed. See comments in ncclimo for documentation.
-m: model type. Default is "cam". Other options are "clm2", "ocn", "ice", "cism", "cice", "pop".
MPAS O/I considerations:
MPAS ocean and ice models currently have their own (non-CESM'ish) naming convention for monthly output files. ncclimo recognizes input files as being MPAS-style when invoked with "-c hist" and "-m ocn" or "-m ice". Use the optional "-f fml_nm" switch to replace "hist" with a more descriptive simulation name for the output. Invocation looks like this:
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