CDO

Hi,

I am working with sub-daily (6-hrly) MSLP data from ERA-Interim. I’ve calculated the mean MSLP for each year using ‘yearmean’ - e.g., cdo yearmean subdaily_MSLP_1979.nc mean_MSLP_1979.nc - and I am now trying to subtract the mean from the individual time steps. I’ve trying using ‘sub’ - e.g., cdo sub subdaily_MSLP_1979.nc mean_MSLP_1979.nc removed_mean_1979.nc - and am getting the following error:

cdo sub: Filling up stream2 >mean_MSLP_1979.nc< by copying the first timestep.

cdo sub (Abort): Fields have different gridsize (farsub)

I can’t figure out why the error is arising as both files (subdaily_MSLP_1979.nc and mean_MSLP_1979.nc) have the same lat, long, and gridsize. The only difference between the files (with the exception of the actual MSLP data values) should be the number of timesteps. The subdaily_MSLP_1979.nc file has a start data time stamp of 1979-01-01 00:00:00 while mean_MSLP_1979.nc has a start date time stamp of 1979-07-02 09:00:00. I’ve tried setting the data and time (using ‘setdate’ and ‘settime’, respectively) to 1979-01-01 00:00:00 for the mean_MSLP_1979.nc data but am still getting the different gridsize error. Help addressing this issue would be much appreciated!

Thanks!