# Different approaches to quantify light pollution on a given location on Earth?

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:

1. Look what you can observe with naked eye and use the Bortle scale.
2. Use a Sky quality meter of any kind and measure luminance.
3. 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.
4. 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?