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Regridding is a standalone operation carried out by ncremap. See the full ncremap documentation for examples of standalone operation (including MPAS!). For convenience, ncclimo will (optionally) call ncremap to regrid during climatology generation to produce climatology files on both the native and desired analysis grids. Only the ncremap features most relevant to ncclimo are described here. Regridding while producing climos is virtually free, because it is performed on idle nodes/cores after the monthly climatologies have been computed and while the seasonal climatologies are being computed. This load-balancing can save half an hour on ne120 datasets. To regrid, simply pass the desired mapfile name with "-r map.nc", e.g., "-r ${DATA}/maps/map_ne120np4_to_fv257x512_aave.20150901.nc". Although this should not be necessary for normal use, you may pass any options specific to regridding with "-R opt1 opt2".
Specifying '-O drc_rgr' (NB: uppercase "O") causes ncclimo to place the regridded files in the directory ${drc_rgr}. These files have the same names as the native grid climos from which they were derived. There is no namespace conflict because they are in separate directories. These files also have symbolic links to their AMWG filenames. If '-O drc_rgr' is not specified, ncclimo places all regridded files in the native grid climo output directory, ${drc_out}, specified by '-o drc_out' (NB: lowercase "o") . To avoid namespace conflicts when both climos are stored in the same directory, the names of the regridded files are suffixed by the destination geometry string obtained from the mapfile, e.g., '*_climo_fv257x512_bilin.nc'. These files also have symbolic links to their AMWG filenames.
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ls drc_out/*climo* | ncremap -m map.nc -O drc_rgr
As of 20170526 and version 4.6.7, ncremap supports sub-gridscale (SGS) regridding. Though designed for ALM and CICE, this feature is configurable for other SGS datasets as well. In sub-grid mode, ncremap performs substantial pre- and post-processing so that regridding conserves fields that may represent only a fraction of the entire gridcell. The sub-gridscale fraction represented by each field is contained in a variable (set with the option "--sgs_frc") whose default is "landfrac". SGS mode eases regridding of datasets (e.g., from ALM, CLM, and non-MPAS versions of CICE) that output data normalized to a gridcell fraction rather than to its entire extent. SGS mode automatically derives new binary masks ("--sgs_msk", defaults to "landmask") and allows for additional normalization ("--sgs_nrm"). Specific flavors of SGS can be selected (with "-P alm", or clm, or cice). These ensure regridded datasets recreate the idiosyncratic units (e.g., %, km2) employed by raw ALM, CLM, and CICE model output.
ncremap -P sgs -s src_grd.nc -i in.nc -d 1x1.nc -o rgr.nc
ncremap -P alm -s src_grd.nc -i alm.nc -d 1x1.nc -o rgr.nc
ncremap -P cice -s src_grd.nc -i cice.nc -d 1x1.nc -o rgr.nc
ncremap -P sgs --sgs_frc=aice --sgs_msk=tmask --src_nrm=100 -s src_grd.nc -i in.nc -d 1x1.nc -o rgr.nc
Full documentation on SGS mode is here: http://nco.sf.net/nco.html#sgs. Note that ncclimo does not (yet anyway) call ncremap with the SGS option. One gets SGS features only by manually invoking ncremap as above. This is mainly because parallelization with SGS is much more efficient with standalone ncremap than through ncclimo. We solicit your feedback on SGS behavior and future features...
Coupled Runs:
ncclimo works on all ACME models. It can simultaneously generate climatologies for a coupled run, where climatologies mean both native and regridded monthly, seasonal, and annual averages as per the AG specification. Here are template commands for a recent simulation:
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