The question Light Pollution: what is the difference between artificial brightness and brightness and SQM made me wonder which different ways exist to directly and indirectly quantify light pollution at a given location on the Earth's surface? The obvious sources like Wikipedia etc. did not satisfiy my curiosity.
What I came up so far as a list of different methods is the following:
- Look what you can observe with naked eye and use the Bortle scale.
- Use a Sky quality meter of any kind and measure luminance.
- Use the measurements of a pyranometer of your friendly metereologist or of an automatic weather station nearby and callibrate how many ${\rm W}/{\rm m}^2$ correspond to what value on the Bortle scale.
- Use satellite data of any kind to obtain an approximate
- If your urban area is bright enough, you could see that and in the visible spectrum of any weather satellite, and deduce a lower bound, i.e. how bright it must be at least on the ground.
- The US's DOD might release maps from the Defense Metorological Satellite Program every now and then.
I am sure this list is not exhaustive - which other approaches am I missing?