I am coding a new parser to read values directly from a weather station. Meanwhile, I found something about the solar radiation units that I would like to confirm.
1) The SOLARRADIATION unit described in RainMachine documentation (https://support.rainmachine.com/hc/en-us/articles/228620727-How-to-integrate-RainMachine-with-different-weather-forecast-services) is:
SOLARRADIATION = "SOLARRADIATION" #[megaJoules / square meter per hour]
2) The asceDaily formula (https://github.com/sprinkler/rainmachine-developer-resources/blob/master/formula/formula.py) use the same unit.
fRs = 16.502 [MJ m-2 h-1]
3) The conversion function RMUtils.convertRadiationFromWattsToMegaJoules is applying a conversion factor of 0.0864.
This conversion factor generates a different unit than expected. as described (http://www.fao.org/3/X0490E/x0490e0i.htm) the conversion 1 W m-2 = 0.0864 MJ m-2 day-1 returns de solar radiation per day and not per hour.
Can you confirm that the conversion factor from watts to megajoules is correct?
From my point of view, the conversion factor should be 0.0036. From the maths we have:
1 W/m2 = 1 J/m2/Sec
1 J/m2/Sec * 3600 Sec/Hour = 3600 Joules/m2/Hour
3600 Joules/m2/Hour / 1,000,000 = 0.0036 MJ/m2/Hour
You could use 0.0036 as a direct multiplier to get from W/m2 to MJ/m2/Hour.
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