bandpass filtering
Added by mini max over 2 years ago
Hi Guys,
I need to bandpass filtering (2-10 days) hourly data (wind_hourly.nc) and for that I'm doing the following commands:
highcut = (365*24/2*24)/(365*24/2); %define highcut frequency 2 days accounting Nyquist theorem
lowcut =(365*24/10*24)/(365*24/2); %define lowcut frequency 10 days accounting Nyquist theorem
cdo bandpass,$lowcut,$highcut -detrend -del 29feb wind_hourly.nc filtered_wind.nc
Am I doing all correct?
thank you for your help!
Replies (1)
RE: bandpass filtering - Added by Ralf Mueller over 2 years ago
hi!
frequencies should in per year. you can always cross check your frequencies with artificial datasets like
cdo -settaxis,2000-01-01,12:00:00,1months -expr,'t=sin(seq*3.141529/180.0)' -for,1,1000
or you plot it
cdo -graph,device=png -settaxis,2000-01-01,12:00:00,1months -expr,'t=sin(seq*3.141529/180.0)' -for,1,1000 artificialData
Now you can insert your bandpass between graph and settaxis to check the filter results
hth
ralf