--- name: "ncra" section: "1" platform: "linux" package: "nco" version: "5.3.3-1" release: "Debian 13 (Trixie)" platforms: ["linux"] url: "https://new.carta.tech/ncra" --- # ncra(1) netCDF Record Averager ## NAME ncra - netCDF Record Averager ## SYNTAX ncra \[-3\] \[-4\] \[-5\] \[-6\] \[-7\] \[-A\] \[--bfr *sz\_byt*\] \[-C\] \[-c\] \[--cb *y1,y2,m1,m2,tpd*\] \[--cmp *cmp\_sng*\] \[--cnk\_byt *sz\_byt*\] \[--cnk\_csh *sz\_byt*\] \[--cnk\_dmn *nm,sz\_lmn*\] \[--cnk\_map *map*\] \[--cnk\_min *sz\_byt*\] \[--cnk\_plc *plc*\] \[--cnk\_scl *sz\_lmn*\] \[-D *dbg\_lvl*\] \[-d *dim*,\[ *min*\]\[,\[ *max*\]\]\[, *stride*\[\[,\[ *subcycle*\[\[,\[ *interleave*\]\]\]\]\]\] \[--dbl\|flt\] \[-F\] \[--fl\_fmt=fmt\] \[-G *gpe\_dsc*\] \[-g *grp*\[,...\]\] \[--glb *att\_name=* *att\_val*\]\] \[-H\] \[-h\] \[--hdf\] \[--hdr\_pad *sz\_byt*\] \[--hpss\_try\] \[-L *dfl\_lvl*\] \[-l *path*\] \[--mro\] \[--msa\] \[-N\] \[-n *loop*\] \[--no\_cll\_msr\] \[--no\_cll\_mth\] \[--no\_frm\_trm\] \[--no\_tmp\_fl\] \[-O\] \[-p *path*\] \[--prm\_int\] \[--prw *wgt\_arr*\] \[--qnt *var1*\[, *var2*\[,...\]\]= *prc*\]\] \[--qnt\_alg *alg\_nm\]* \[-R\] \[-r\] \[--ram\_all\] \[--rec\_apn\] \[-t *thr\_nbr*\] \[--uio\] \[--unn\] \[-v *var*\[,...\]\] \[-w *wgt*\] \[-X *box*\] \[-x\] \[-Y *prg\_nm*\] \[-y *op\_typ*\] *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 \. ## COPYRIGHT Copyright © 1995-present 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 Users 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 Users Guide** are the PDF (recommended), DVI, and Postscript versions at \, \, and \, respectively. HTML and XML versions are available at \ and \, 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. [**ncap2**(1)](/ncap2/1.md), [**ncatted**(1)](/ncatted/1.md), [**ncbo**(1)](/ncbo/1.md), [**ncclimo**(1)](/ncclimo/1.md), [**nces**(1)](/nces/1.md), [**ncecat**(1)](/ncecat/1.md), [**ncflint**(1)](/ncflint/1.md), [**ncz2psx**(1)](/ncz2psx/1.md), [**ncks**(1)](/ncks/1.md), [**nco**(1)](/nco/1.md), [**ncpdq**(1)](/ncpdq/1.md), [**ncra**(1)](/ncra/1.md), [**ncrcat**(1)](/ncrcat/1.md), [**ncremap**(1)](/ncremap/1.md), [**ncrename**(1)](/ncrename/1.md), [**ncwa**(1)](/ncwa/1.md) ## HOMEPAGE The **NCO** homepage at \ contains more information.