I have been trying to estimate instantaneous total solar irradiance(w/m2) at five minute interval for a day (eg. 21 sept). I can do this in SAGA GIS by using "moment, mode 1" and running the solar module for 12*24 time.

Therefore, for automation purpose I want to stick to GRASS. I have looked into r.sun and r.sun.hourly however I am unable to use these function to produce output at 5 minute interval.

Here is the sample code from r.sun.hourly

r.sun.hourly -t elevation=example_data@PERMANENT start_time=6 end_time=18 
             time_step=.08 day=277 year=2011 beam_rad_basename=beam
             diff_rad_basename=dif glob_rad_basename=tot nprocs=6

GRASS GIS addin r.sun.hourly can be used to calculate instantaneous solar radiation flux(w/m2) at an specified interval. By default it is set to run at an hourly instance however by changing the 'time_step' parameter can change the time instant for the run. For eg if you want the total irradiance every two minutes, this is how the parameters would look like.

r.sun.hourly -t elevation=dem@filtered linke_value=2 start_time=6 end_time=18 
             time_step=.01 day=265 year=2008 glob_rad_basename=tot nprocs=6

You might also want to check creating time-space object in the parameters as it will help other operations much easier.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.