We measured air temperature, wind velocity, and relative humidity over the summer and would like to calculate PET values with Rayman Pro. Unfortunately we didn't measure radiation, SVF or the like - so can we still run the model and expect robust results for PET? What is Tmrt based on when we don't indicate any radiation, sky view, etc?
A quick reply would be much appreciated! Thank you.
please excuse my late response, unfortunately Dominik is not working on RayMan anymore.
If you dont specify radiation, sky view factor, cloud cover, the unobstructed clear-sky conditions are considered. If you conducted your measurements in an complex urban environment, you'll need SVF for robust results, because the urban radiation regime is changed due to the coverage of the upper hemisphere.
Maybe you have an 3D city model with all buildings, then you can derive SVF with the urban microscale model SkyHelios.
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)" ??
you need to check the variables of your meteorological data. Global radiation will be calculated based on your cloud cover and your specified geographic location.