Hi,
I have to find out the daily hours of sunshine throughout the year for different climate zones, in particular for Frankfurt am Main, Paris, Milan, Algeria, Niger, the Gobi Desert and Australia. Where and how can I find the data?
I am using https://search.earthdata.nasa.gov/. Is this the right link?
Many thanks in advance for your help.
Best regards,
P
Sunhours per day
Re: Sunhours per day
You could compute the number of sunshine hours per day using sunrise and sunset times, for which there are several calculators. For example:
https://github.com/arthur-e/suntransit
If you want to use NASA data, you could estimate the number of sunshine hours (to the nearest hour) using downwelling, short-wave radiation (i.e., solar radiation), such as from MERRA-2:
https://dx.doi.org/10.5067/Q9QMY5PBNV1T
A threshold of 10 W m-2 has been proposed previously (Mu et al. 2011); i.e., when down-welling short-wave radiation ("SWGDN" in MERRA-2) is less than 10 W m-2, it is "night-time."
Mu, Q., M. Zhao, and S. W. Running. 2011. Improvements to a MODIS global terrestrial evapotranspiration algorithm. Remote Sensing of Environment 115 (8):1781–1800.
https://github.com/arthur-e/suntransit
If you want to use NASA data, you could estimate the number of sunshine hours (to the nearest hour) using downwelling, short-wave radiation (i.e., solar radiation), such as from MERRA-2:
https://dx.doi.org/10.5067/Q9QMY5PBNV1T
A threshold of 10 W m-2 has been proposed previously (Mu et al. 2011); i.e., when down-welling short-wave radiation ("SWGDN" in MERRA-2) is less than 10 W m-2, it is "night-time."
Mu, Q., M. Zhao, and S. W. Running. 2011. Improvements to a MODIS global terrestrial evapotranspiration algorithm. Remote Sensing of Environment 115 (8):1781–1800.
Re: Sunhours per day
The MERRA-2 down-welling short wave radiation data do indeed account for cloud cover, so it could be normalized in some fashion to compute sunshine hours. But, yes, the ephemeris table approach considers only potential sunshine or "daylight" hours.