ncecat concatenates an arbitrary number of input files into a single output file. Input files are glued together by creating a record dimension in the output file. Input files must be the same size. Each input file is stored consecutively as a single record in the output file. Thus, the size of the output file is the sum of the sizes of the input files.

Consider five realizations, 85a.nc, 85b.nc, 85e.nc of 1985 predictions from the same climate model. Then ncecat 85?.nc 85_ens.nc glues the individual realizations together into the single file, 85_ens.nc. If an input variable was dimensioned [ lat, lon], it will have dimensions [ record, lat, lon] in the output file. A restriction of ncecat is that the hyperslabs of the processed variables must be the same from file to file. Normally this means all the input files are the same size, and contain data on different realizations of the same variables.

Consider 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 all the seasonal cycles. Here the numeric filename suffix denotes the experiment number (not the month):

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

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.