Aggregate different netcdf variables and write output

Question

I have a netcdf files with 3 variables, nammed v1, v2, v3. I would like to aggregate those variables and create a new variable v4, as follow:

v4 = (v1*0.1)+(v2*0.2)+(v3*0.2)

I know how to aggregate 2 variables using cdo :

cdo expr,’sum=var1+var2;’ ifile ofile

But how could I handle more specific netcdf calculations like the one required?

Answer 1

CDO will be able to handle the formula you require:

cdo expr,’v4=(v1*0.1)+(v2*0.2)+(v3*0.2)’ ifile ofile

If you want to add the variable to the files, just do this:

cdo aexpr,’sum=var1+var2;v4=(v1*0.1)+(v2*0.2)+(v3*0.2)’ ifile ofile