How can I convert the negative values of the ERA5 PET data into positive? I planned to use the ERA5 Potential evapotranspiration data for drought analsysis (SPEI), however values are presented in negative number. Of course I understand the logic for presenting PET negative. But, I want to convert it into positive and I should all the PET data positive. I knowledge those who help me to change the negative value in to positive. I am using cdo for data processing. Thank you!
Mekonnen Adnew Degefu
You can multiply all the values by -1

cdo mulc,-1 infile.nc outfile.nc


If you want also to get rid of the condensation data (and, please, note that I am not implying that that is the right thing to do), you can do something like this

cdo setrtoc,0,9999,0 ifile.nc ofile.nc


Hope this helps