What kind of physical parameter can we use to describe reflectivity?
Some phenomena in the atmosphere like glow of the setting sun, lunar halo, and rainbows are caused by scattering or absorption of light of floating particles in the air. The term ‘Optical Depth’ is used as a indication which represents the amount of scattering and absorption. Aerosol Optical Depth(AOD) refers to the amount of solar radiation declined by aerosols existing in the air along the path to the surface.
I denotes radiation strength before passing aerosols, Io denotes radiation strength after passing aerosols, and τ denotes aerosol optical depth. Thus, aerosol optical depth can be represented as below.
The fact that if the amount of incidence light decreases by 1/e, AOD would be 1 can be noticed through the equation. The weaker the radiation becomes after passing aerosols, which means the air has the higher concentration of aerosols, AOD would increase.
As mentioned above, AOD indicates the amount of both scattering and absorption, AOD can be divided into two section, absorption AOD and reflection AOD, and represented as ‘Overall AOD = Absorption AOD + Scattering AOD’.
As mentioned above, AOD indicates the amount of both scattering and absorption, AOD can be divided into two section, absorption AOD and reflection AOD, and represented as ‘Overall AOD = Absorption AOD + Scattering AOD’.