If you have one big data with time period from 1979 to 2014,
and you really want to make two data with tow split time.
Then, use this one, “select time (seltime)”
Format: cdo selyear, year1, year2 input.nc output.nc
* for selecting period from 1979 to 1980 year from “test.nc”
cdo selyear,1979/1997 test.nc test.1979-1980.nc
(ref) cdo seltimestep,21/70 input_file.nc output_file.nc
Super, Simple :)