The function is called “sub” is not working for subtracting between the value with all time series and the averaged value in all time series. Because the averaged value doesn’t have same number of time series with original data. It have only one time series.
so, “sub” is mostly good for the subtraction between values have same time series.
therefore, I recommend to use “ymonsub or monsub” for subtracting averaged value in all time period.
$ cdo ymonsub data.nc –ymonmean data.nc data_subtracted_average.nc
just try it, then you feel it.
So, Simple 🙂