CDO

Joe,

Does an operator like seasmean or yseasmean do what you want? If not, you could probably use timselmean to do it as there is an example that seems to echo what you want:

Assume an input dataset has monthly means over several years. To compute seasonal means from monthly means the first two month have to be skipped:
  cdo timselmean,3,2 ifile ofile

yseasmean does what I want except it does not take into account the different weights (days per month) of individual months. yearmonmean does do this for yearly averages but I don't think there is a yseasmonmean. I've tried, unsuccessfully to string together yseasmean something like muldpm. I'm sure there is a way to do this but I'm not sure what the right chain of operators would be.

Hi Joe,

Did you ever find a solution for this? There doesn't seem to be any cdo command that does it.

Thank you,

François Roberge

Hi Françoise,

try

cdo -ymonmean infile.nc outfile_ymm.nc

cdo -seasmean outfile_ymm.nc outfile.nc

-Karin

Hi Karin,

Yes but by doing this way, the seasonal means won’t be weighted according to the number of days per each month.

Thank you,

François

Here is one workaround, using DJF as an example:

cdo -ymonmean infile.nc tmp1.nc
cdo -selmon,12,1,2 tmp1.nc tmp2.nc
cdo -timmean tmp2.nc outfile.nc

XR Chua wrote:

Here is one workaround, using DJF as an example:

cdo -ymonmean infile.nc tmp1.nc
cdo -selmon,12,1,2 tmp1.nc tmp2.nc
cdo -timmean tmp2.nc outfile.nc

HI Xr Chua,

tmp1.nc contains only one timestep per month so by doing timmean, you are doing the mean over three time steps which doesn't consider the weights according to the number of days per each month.

Thank you,

François

My bad, I meant yearmonmean instead of timmean:


cdo -ymonmean infile.nc tmp1.nc
cdo -selmon,12,1,2 tmp1.nc tmp2.nc
cdo -yearmonmean tmp2.nc outfile.nc

Thanks for the catch!