CDO

Hi there! I'm new to CDO and I need help in generating the stream function of the file I have

I currently have a netcdf file which contains the 850 hPa u and v winds of a certain region. I got this from the ERA5 dataset

I want to use the "cdo uv2dv" function and then use the "cdo dv2ps" so the my u and v wind file can be converted into divergence and vorticity which can be converted to the stream function and velocity potential.

But whenever I do the first function, I get the error:

Too few streams specified! Operator uv2dv needs 1 input stream and 1 output stream!

I also know of the "cdo mastrfu" function but it gives me the error:

Warning (cdfScanVarAttr): NetCDF: Variable not found - >isobaricInhPa<
Warning (cdf_check_variables): Unsupported data type (char/string), skipped variable expver!
Warning (cdf_check_variables): 4 dimensional variables without time dimension are not supported, skipped variable u!
Warning (cdf_check_variables): 4 dimensional variables without time dimension are not supported, skipped variable v!
Warning (cdf_check_variables): 4 dimensional variables without time dimension are not supported, skipped variable vo!
Warning (cdfInqContents): No data arrays found!

Any help?