Ncea creates ensemble averages. It is generally used when you have several years of data, and you want to create an ensemble, or average, of those years (i.e., going from individual year files to mone files).
Creating an ensemble (average) of five years of data
If you have five files, each of which have twelve months of data in them (Jan-Dec). You want to create an ensemble (average) of these five years.
If the files are:
Then the command would be:
ncea -n 5,5,1 ha.F1.PBC_TPBOX.00510.nc ha.F1.PBC_TPBOX.510_514.nc
- 5 is the number of files in the ensemble
- 5 is the digit_number, the fixed number of numeric digits comprising the numeric_suffix (00510, 00511, 00512, etc.)
- 1 is the numeric_increment, the constant, integer-valued difference between the numeric_suffix of any two consecutive files
- ha.F1.PBC_TPBOX.00510.nc is the first input file in the series
- ha.F1.PBC_TPBOX.510_514.nc is the output file name
Creating seasonal files from monthly files
If you have three files representing March (moni03.nc), April (moni04.nc), and May (moni05.nc), you can create a file that is the average of those three files - a spring average (March-April-May).
The command would be:
ncea -n 3,2,1 moni03.nc mami.nc
- 3 is the number of files
- 2 is the number of digits in the file name
- 1 is the increment