Light spectrum of planet Earth as seen from space

[William LL]

Has the spectrum of light that is reflected off planet Earth ever been measured from outer space? (In the same sense that we measure spectra of the light emitted/reflected from other celestial bodies in astronomy). If so, would it be possible that there could be dips in the spectrum resulting from absorption by solid substances on the surface of the planet, not just gases in the atmosphere?

 

[stefan r]

Yes, that has been measured. Oceans, ice, trees, dirt, and pavement give off very different spectra. Early cold war spy satellites could see where people had walked at night because grass with dew on it emits different wavelengths than grass without dew. A lot of weather forecasting uses satellite images. There are a lot of them aimed at earth.

 

[William LL]

Thanks for the reply, i have another question.
Where could one find a graph showing the intensity-wavelength graph of said light spectrum? I've been searching on google and so far I've only found data on the atmospheric absorbance, not on the emission spectrum of Earth as a whole.

 

[stefan r]

Most people looking at that are interested in the atmospheric absorption. The raw data is the spectrum that you want. The atmospheric absorption is calculated by subtracting reflected sunlight and ground level emission. https://www.ncdc.noaa.gov/data-access/satellite-data/satellite-data-access-sorted-satellite-instrument. I tried to look at the data but my computer did not recognize the "tar" file. Anyway you can get the raw data from National Center for Environmental Information.

Most satellites use instruments in a narrow band of wavelengths. To get the full spectrum you would need to combine data from multiple satellites.

The emission spectrum of Earth as a whole changes. seasons, day vs night, current weather, which direction you look from, Pacific vs Atlantic etc, pole vs equator, etc. The geostationary satellites only look at one area.