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In climatology generation mode, the NCO operator ncclimo ingests "raw" data consisting of interannual sets of files, each containing sub-daily (diurnal), daily, monthly, or yearly averages, and from these produces climatological daily, monthly, seasonal, and/or annual means. Alternatively, in timeseries reshaping (aka “splitter”) mode, ncclimo will subset and temporally split the input timeseries into per-variable files spanning the entire period. ncclimo will optionally regrid (by calling ncremap) all output files in either mode. The primary ncremap 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. , and delves into regridding options in much great depth than the below instructions for climatology generation.
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Prerequisites
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A common task for ncclimo is to produce climatological monthly, seasonal, and annual-means from an interannual series of monthly-mean input files with commands like these:
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ncclimo -P eam -s $yr_srt -e $yr_end -c $caseid -i $drc_in -o $drc_out # EAM/CAM/CAM-SE ncclimo -P eam -v FSNT -s $yr_srt -e $yr_end -c $caseid -i $drc_in -o $drc_out # EAM subset ncclimo -P elm -m clm2 -s $yr_srt -e $yr_end -c $caseid -i $drc_in -o $drc_out # ELM/ALM/CLM |
Each option can be accessed by a handful of long-option synonyms to suit users' tastes. With long options the first example above may be rewritten as
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ncclimo --prc_typ=eam --start=$yr_srt --end=$yr_end --case=$caseid --input=$drc_in --output=$drc_out |
When invoked without options ncclimo outputs a handy table of all available options, their long-option synonyms, and some examples. NCO documentation here describes the Note that -P eam above, is not necessary since the default processing type is EAM. However, it is a good habit to specify the component model (if any) to ncclimo since ncremap may require this information in the regridding step. When invoked without options ncclimo outputs a handy table of all available options, their long-option synonyms, and some examples. NCO documentation here describes the full meaning of all options. The most common options are:
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-m, --mdl_nm: Model name. Default is eam. This is similar to, though subtly different than, the -P option (which is preferred to -m). This is literally the string name used in the history tape output files. Other options are cam, clm2, cism, cice, mpasi, mpaso, pop. The best example of when to use -m is for ELM, where -m clm2 informs ncclimo that the ELM input files have “clm2” (not “elm”) in their names. Similarly, use -m cam when EAM files have "cam" (not “eam") in their filename.
-o, --drc_out: 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")
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-P, --prc_typ: Processing type. As of ~2020, use -P to indicate the component model that produced the data, and -m solely to modify the model name string for input files. The standard processing type assumed is EAM files, so -P eam is a no-op. However, processing EAMxx files requires -P eamxx. Other processing types that should always be indicated are clm, cpl (for coupler files), elm, mali, mpasseaice, and mpasocean.
-s, --yr_srt: Start year (example: 1980). By default, the first month used will be Jan of this start year. If -a scd is specified, the first month used will be Dec of the year before this specified start year (example Dec 1979 to allow for temporally contiguous DJF climos).
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MPAS ocean and ice models have their own (non-CESM'ish) naming convention that guarantees output files have the same names for all simulations. By default ncclimo analyzes the timeSeriesStatsMonthly analysis member (AM) output (tell CZ Charlie Zender if you want options for other AM output). ncclimo recognizes input files as being MPAS-style when invoked with -m mpaso or -m mpasseaice (or synonyms) like this:
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