1NCRA(1) General Commands Manual NCRA(1)
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6 ncra - netCDF Record Averager
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9 ncra [-3] [-4] [-5] [-6] [-7] [-A] [--bfr sz_byt] [-C] [-c] [--cb
10 y1,y2,m1,m2,tpd] [--cmp cmp_sng] [--cnk_byt sz_byt] [--cnk_csh sz_byt]
11 [--cnk_dmn nm,sz_lmn] [--cnk_map map] [--cnk_min sz_byt] [--cnk_plc
12 plc] [--cnk_scl sz_lmn] [-D dbg_lvl] [-d dim,[ min][,[ max]][,
13 stride[[,[ subcycle[[,[ interleave]]]]]] [--dbl|flt] [-F]
14 [--fl_fmt=fmt] [-G gpe_dsc] [-g grp[,...]] [--glb att_name= att_val]]
15 [-H] [-h] [--hdf] [--hdr_pad sz_byt] [--hpss_try] [-L dfl_lvl] [-l
16 path] [--mro] [--msa] [-N] [-n loop] [--no_cll_msr] [--no_cll_mth]
17 [--no_frm_trm] [--no_tmp_fl] [-O] [-p path] [--ppc var1[, var2[,...]]=
18 prc]] [--prm_int] [--prw wgt_arr] [-R] [-r] [--ram_all] [--rec_apn] [-t
19 thr_nbr] [--uio] [--unn] [-v var[,...]] [-w wgt] [-X box] [-x] [-y
20 op_typ] input-files output-file
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23 ncra averages record variables across an arbitrary number of input
24 files. The record dimension is retained as a degenerate (size 1) di‐
25 mension in the output variables.
26 Input files may vary in size, but each must have a record dimension.
28 The record coordinate, if any, should be monotonic for (or else non-fa‐
29 tal warnings may be generated). Hyperslabs of the record dimension
30 which include more than one file are handled correctly. ncra supports
31 the stride argument to the -d hyperslab option for the record dimension
32 only, stride is not supported for non-record dimensions.
33 ncra weights each record (e.g., time slice) in the input-files equally.
35 ncra does not attempt to see if, say, the time coordinate is irregu‐
36 larly spaced and thus would require a weighted average in order to be a
37 true time average.
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40 Average files 85.nc, 86.nc, ... 89.nc along the record dimension, and
41 store the results in 8589.nc:
42 ncra 85.nc 86.nc 87.nc 88.nc 89.nc 8589.nc
43 ncra 8[56789].nc 8589.nc
44 ncra -n 5,2,1 85.nc 8589.nc
45 These three methods produce identical answers.
46 Assume the files 85.nc, 86.nc, ... 89.nc each contain a record coor‐
48 dinate time of length 12 defined such that the third record in 86.nc
49 contains data from March 1986, etc. NCO knows how to hyperslab the
50 record dimension across files. Thus, to average data from December,
51 1985 through February, 1986:
52 ncra -d time,11,13 85.nc 86.nc 87.nc 8512_8602.nc
53 ncra -F -d time,12,14 85.nc 86.nc 87.nc 8512_8602.nc
54 The file 87.nc is superfluous, but does not cause an error. The -F
55 turns on the Fortran (1-based) indexing convention. The following uses
56 the stride option to average all the March temperature data from multi‐
57 ple input files into a single output file
58 ncra -F -d time,3,,12 -v temperature 85.nc 86.nc 87.nc
59 858687_03.nc
60 Assume the time coordinate is incrementally numbered such that January,
62 1985 = 1 and December, 1989 = 60. Assuming ?? only expands to the
63 five desired files, the following averages June, 1985--June, 1989:
64 ncra -d time,6.,54. ??.nc 8506_8906.nc
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68 NCO manual pages written by Charlie Zender and originally formatted by
69 Brian Mays.
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73 Report bugs to <http://sf.net/bugs/?group_id=3331>.
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77 Copyright © 1995-present Charlie Zender
78 This is free software; see the source for copying conditions. There is
79 NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR
80 PURPOSE.
81
84 The full documentation for NCO is maintained as a Texinfo manual called
85 the NCO Users Guide. Because NCO is mathematical in nature, the docu‐
86 mentation includes TeX-intensive portions not viewable on character-
87 based displays. Hence the only complete and authoritative versions of
88 the NCO Users Guide are the PDF (recommended), DVI, and Postscript ver‐
89 sions at <http://nco.sf.net/nco.pdf>, <http://nco.sf.net/nco.dvi>, and
90 <http://nco.sf.net/nco.ps>, respectively. HTML and XML versions are
91 available at <http://nco.sf.net/nco.html> and
92 <http://nco.sf.net/nco.xml>, respectively.
93 If the info and NCO programs are properly installed at your site, the
95 command
96 info nco
98 should give you access to the complete manual, except for the TeX-in‐
100 tensive portions.
101 ncap2(1), ncatted(1), ncbo(1), ncclimo(1), nces(1), ncecat(1),
103 ncflint(1), ncz2psx(1), ncks(1), nco(1), ncpdq(1), ncra(1), ncrcat(1),
104 ncremap(1), ncrename(1), ncwa(1)
105
108 The NCO homepage at <http://nco.sf.net> contains more information.
109 NCRA(1)