Dear Marcel Gangwisch,

Thank you for your response to LaMa_1. I have a similar question. I have the following meteorological data in 3 hourly intervals: air temperature (in degree Celsius), relative humidity (in percent), wind speed (in metres per
second) and cloud cover (in oktas i.e. from 1 - 8). I have read the manual and the resources on this forum. its my understanding that RayMan can estimate global radiation (in watts per square metre) based on cloud cover and it can also estimate Vapour Pressure based on Relative Humidity.

QUESTION:

To calculate PET do I still need to follow the guideline given in the manual i.e. In the column selection box on the right, the entries "Date", "Time", "Air temperature Ta (C)", "Vapor pressure VP (hPa)", "Wind velocity v (m/s)" and "Global radiation G ( Wm2 )" need to be checked OR should I check "Date", "Time", "Air temperature Ta (C)", "Relative humidity RH (%)", "Wind velocity v (m/s)", and "Cloud cover N (octas)" ??