Provided by: nco_4.5.4-1build1_amd64 
NAME
ncra - netCDF Record Averager
SYNTAX
ncra [-3] [-4] [-6] [-7] [-A] [--bfr sz][-C][-c][--cnk_byt sz][--cnk_dmn nm,sz] [--cnk_map map]
[--cnk_min sz] [--cnk_plc plc] [--cnk_scl sz][-D dbg_lvl] [-d dim,[ min][,[ max]][, stride[[,[
subcycle]]]]] [--dbl|flt] [-F] [-G gpe_dsc] [-g grp[,...]] [--glb att_name= att_val]] [-h] [--hdf]
[--hdr_pad sz] [-L dfl_lvl] [-l path] [--mro] [--msa] [-N] [-n loop] [--no_cll_mth] [--no_tmp_fl] [-O]
[-p path] [--ppc var1[, var2[,...]]= prc]] [-R] [-r] [--ram_all] [--rec_apn] [-t thr_nbr] [--unn] [-v
var[,...]] [-w wgt] [-X box] [-x] [-y op_typ] input-files output-file
DESCRIPTION
ncra averages record variables across an arbitrary number of input files. The record dimension is
retained as a degenerate (size 1) dimension in the output variables.
Input files may vary in size, but each must have a record dimension. The record coordinate, if any,
should be monotonic for (or else non-fatal warnings may be generated). Hyperslabs of the record
dimension which include more than one file are handled correctly. ncra supports the stride argument to
the -d hyperslab option for the record dimension only, stride is not supported for non-record dimensions.
ncra weights each record (e.g., time slice) in the input-files equally. ncra does not attempt to see if,
say, the time coordinate is irregularly spaced and thus would require a weighted average in order to be a
true time average.
EXAMPLES
Average files 85.nc, 86.nc, ... 89.nc along the record dimension, and store the results in 8589.nc:
ncra 85.nc 86.nc 87.nc 88.nc 89.nc 8589.nc
ncra 8[56789].nc 8589.nc
ncra -n 5,2,1 85.nc 8589.nc
These three methods produce identical answers.
Assume the files 85.nc, 86.nc, ... 89.nc each contain a record coordinate time of length 12 defined
such that the third record in 86.nc contains data from March 1986, etc. NCO knows how to hyperslab the
record dimension across files. Thus, to average data from December, 1985 through February, 1986:
ncra -d time,11,13 85.nc 86.nc 87.nc 8512_8602.nc
ncra -F -d time,12,14 85.nc 86.nc 87.nc 8512_8602.nc
The file 87.nc is superfluous, but does not cause an error. The -F turns on the Fortran (1-based)
indexing convention. The following uses the stride option to average all the March temperature data from
multiple input files into a single output file
ncra -F -d time,3,,12 -v temperature 85.nc 86.nc 87.nc 858687_03.nc
Assume the time coordinate is incrementally numbered such that January, 1985 = 1 and December, 1989 = 60.
Assuming ?? only expands to the five desired files, the following averages June, 1985--June, 1989:
ncra -d time,6.,54. ??.nc 8506_8906.nc
AUTHOR
NCO manual pages written by Charlie Zender and originally formatted by Brian Mays.
REPORTING BUGS
Report bugs to <http://sf.net/bugs/?group_id=3331>.
COPYRIGHT
Copyright © 1995-2016 Charlie Zender
This is free software; see the source for copying conditions. There is NO warranty; not even for
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
SEE ALSO
The full documentation for NCO is maintained as a Texinfo manual called the NCO User's Guide. Because
NCO is mathematical in nature, the documentation includes TeX-intensive portions not viewable on
character-based displays. Hence the only complete and authoritative versions of the NCO User's Guide are
the PDF (recommended), DVI, and Postscript versions at <http://nco.sf.net/nco.pdf>,
<http://nco.sf.net/nco.dvi>, and <http://nco.sf.net/nco.ps>, respectively. HTML and XML versions are
available at <http://nco.sf.net/nco.html> and <http://nco.sf.net/nco.xml>, respectively.
If the info and NCO programs are properly installed at your site, the command
info nco
should give you access to the complete manual, except for the TeX-intensive portions.
ncap(1), ncap2(1), ncatted(1), ncbo(1), nces(1), ncecat(1), ncflint(1), ncks(1), nco(1), ncpdq(1),
ncra(1), ncrcat(1), ncremap(1), ncrename(1), ncwa(1)
HOMEPAGE
The NCO homepage at <http://nco.sf.net> contains more information. NCRA(1)