NCES(1)

💅 NCES(1) 💅

okay so bestie, welcome to the NCES(1) page, straight outta the General Commands Manual 🌈 — this is the netCDF Ensemble Statistics girlie and she is iconic, no cap ✨

---

🎀 NAME 🎀

nces — netCDF Ensemble Statistics 💖 (yes that's literally the whole name, she's mysterious like that)

---

✨ SYNTAX ✨

lowkey a lot of flags but we eat them for breakfast, bestie 🍓

nces [-3] [-4] [-5] [-6] [-7] [-A] [--bfr sz_byt] [-C] [-c] [--cb y1,y2,m1,m2,tpd] [--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]]] [--dbl|flt] [-F] [--fl_fmt=fmt] [-G gpe_dsc] [-g grp[,...]] [-h] [--hdf] [--hdr_pad sz_byt] [-L dfl_lvl] [-l path] [--msa] [-N] [-n loop] [--no_cll_msr] [--no_frm_trm] [--no_tmp_fl] [--nsm_sfx grp_sfx] [-O] [-p path] [--ppc var1[, var2[,...]]= prc]] [-R] [-r] [--ram_all] [-t thr_nbr] [--uio] [--unn] [-v var[,...]] [-X box] [-x] [-y op_typ] input-files output-file

---

🦋 DESCRIPTION 🦋

okay so here's the tea ☕ nces does gridpoint averages of variables across an arbitrary number (an ensemble) of input files, and every single file gets an equal weight in that average. periodt 💅

so the way that works: each variable in the output-file is gonna be the same size as the same variable in any one of the input-files, and like — all input-files must be the same size, that's non-negotiable bestie 🫶

now, comparing her to her cousin ncra (iykyk): ncra only performs averages over the record dimension (e.g., time), and it weights each record in the record dimension evenly. but nces? she averages entire files, and weights each file evenly. main character energy fr fr 👑

and not me pointing out that all dimensions, including the record dimension, are treated identically and preserved in the output-file — no special treatment, everyone's equal in this house 🏠✨

now for the lore 📖 the file is the logical unit of organization for the results of many scientific studies. often one wishes to generate a file which is the gridpoint average of many separate files. maybe it's to reduce statistical noise by combining the results of a large number of experiments, or maybe it's simply a step in a procedure whose goal is to compute anomalies from a mean state. in any case, when one desires to generate a file whose properties are the mean of all the input files, then nces is the operator to use. slay 💖

and here's the detail that matters: nces assumes coordinate variable are properties common to all of the experiments and so does not average them across files. instead, nces copies the values of the coordinate variables from the first input file to the output file. yes, the first one, don't come for her 💀

---

🌸 EXAMPLES 🌸

okay imagine this: a model experiment which generated five realizations of one year of data, say 1985. you can imagine that the experimenter slightly perturbs the initial conditions of the problem before generating each new solution. assume each file contains all twelve months (a seasonal cycle) of data and we want to produce a single file containing the ensemble average (mean) seasonal cycle. here the numeric filename suffix denotes the experiment number (not the month):

nces 85_01.nc 85_02.nc 85_03.nc 85_04.nc 85_05.nc 85.nc
nces 85_0[1-5].nc 85.nc
nces -n 5,2,1 85_01.nc 85.nc

these three commands produce identical answers 🤯 the output file, 85.nc, is the same size as the inputs files. it contains 12 months of data (which might or might not be stored in the record dimension, depending on the input files), but each value in the output file is the average of the five values in the input files. chef's kiss 🧑‍🍳💋

in the previous example, the user could have obtained the ensemble average values in a particular spatio-temporal region by adding a hyperslab argument to the command, e.g.,

nces -d time,0,2 -d lat,-23.5,23.5 85_??.nc 85.nc

in this case the output file would contain only three slices of data in the time dimension. these three slices are the average of the first three slices from the input files. additionally, only data inside the tropics is included. the range she has 🌴✨

---

👑 AUTHOR 👑

NCO manual pages written by Charlie Zender and originally formatted by Brian Mays. legends only, we stan 💜

---

😭 REPORTING BUGS 😭

Report bugs to <http://sf.net/bugs/?group_id=3331>. pls do it, she wants to grow 🌱

---

💖 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.

bestie this one is serious okay — NO warranty, capital letters, that's not a vibe, that's a legal fact 🚨

---

🌈 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 <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. (so close, yet so far 😔)

ncap2(1), ncatted(1), ncbo(1), ncclimo(1), nces(1), ncecat(1), ncflint(1), ncz2psx(1), ncks(1), nco(1), ncpdq(1), ncra(1), ncrcat(1), ncremap(1), ncrename(1), ncwa(1) — the whole friend group 💕

---

🧚 HOMEPAGE 🧚

The NCO homepage at <http://nco.sf.net> contains more information. go lurk, it's giving archives 📚✨

---

and that's the entire NCES(1) page, bestie — General Commands Manual girlie, ensemble-averaging icon, doing her thing since forever 🌟 mwah, ily, go average something 💋💅🎀