Earthdata Forum

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

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.

That's daylight hours, not actual sunshine.

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.