CDO

Say I have two files a(lat,lon,z,time) and b(lat,lon,z,time). Both files have a certain number of variables.

Lat,lon,time are the same for the two files

I want to be able to multiple, add, etc variables across specific levels across these two files.

The last step would be to calculate the average across the last x number of years for each variable in the netcdf. So the result would be average(lat,lon,z) for each variable.

I have managed to get my result, which I think it's correct, but it seems I had to go through many intermediate steps. Is there a more efficient way to do this?

in myexpr I use variab3 = sellevel(variable1,10)+sellevel(variable2,11);

#make some calculation in file a
cdo exprf,myexpr a.nc a1.nc

cdo expr,'anpop=ani_popu_all*10^6;' b.nc b1.nc

cdo merge a1.nc b1.nc total.nc

cdo exprf,morecalc total.nc popcalc.nc

cdo yearmean popcalc.nc yearlm.nc

cdo -select,timestep=-5/-1 yearlm.nc yearlm5.nc

cdo timavg yearlm5.nc yearlmall.n

Also, should I use timavg or fldavg, I don't really understand the differences.