Cooling degree days
Added by Guilong Li over 10 years ago
Hi,
CDO has a function to calculate heating degree days. Now I want to calculate cooling degree days. Because CDO doesn't have this function, I do some changes for the data in order to use eca_hd to calculate the cooling degree days.
First, I reverse the data using cdo expr,'tmean=(18-tmean+273.15)' tmean.nc tmean1.nc to reverse the temperature and change Celsius to Kelvin, then I use cdo eca_hd,0 tmean1.nc cdd.nc, here I use 18C as a threshold.
But I get a lot of negative value in cdd.nc, I don't know why.
Can someone tell me where I did wrong?
Thanks,
Guilong
Replies (1)
RE: Cooling degree days - Added by Guillaume Mauger almost 9 years ago
Hi Guilong,
I found your post in trying to calculate cooling degree days myself, and have found the same error. This seems to be a bug in the CDO command "_expr_" (at least when it comes to netcdf4 files -- I haven't tested this with netcdf3 files).
If I instead use the NCO command: "_ncap2 -s 'tmean=(18-tmean+273.15)' tmean.nc tmean1.nc_", then I get the correct answer.
I like your approach better than the alternative presented here -- [[https://code.zmaw.de/boards/1/topics/446]] -- which in my opinion is more convoluted.
Cheers,
Guillaume