Aethalometers are used to estimate the light-absorbing aerosols or Black Carbon (BC) or Soot particles. There are widely used aethalometers which are measuring light absorption in multiple wavelengths with 5 to 7 channels. While absorption in IR channel is used to quantify the amount of BC but several studies are using UV and IR absorption to quantify the biomass burning/wood burning etc. Literature mentions it as Delta (UV-IR) absorption since organic aerosol absorbs in a comparative lower (near UV) wavelength and estimates Angstrom exponent to apportion the related source of light-absorbing particles. Even though there are other available measurements of light absorption in different wavelengths, what is the use of that?
Measurement at different wavelengths allows spectral analysis for different purposes, such as mineral dust detection and source apportionment atc. Equivalent black carbon concentration is calculated using light attenuation at 880 nm and MAC value 7.77 m2g−1 because absorption due to other aerosols is negligible at this wavelength and hence it can be assumed that absorption at this wavelength is only because of equivalent black carbon.
The Angstrom parameter, can also give information on the size of the aerosols. This can help classify the particles in clusters and identify them. For example, small and absorbent particles, big and less absorbent, etc...
One of the main objective of multi-wavelength measurements by aethalometer is the possibility to determine the aerosol Absorption Angstrom Exponent (AAE), which provides important information on aerosol size and type. If you can associate multi-wavelength aethalometer and nephelometer measurements in order to estimate simultaneous absorption and scattering Angstrom exponent values, you can define a graphical framework with a AAE vs SAE plot and in this way you can have more information on the aerosol type.
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