Astronomical Techniques Applied to Pollution Detection. 2. Chemical Compositions by Visible Extinction

摘要

A technique has been developed in which chemical composition information for atmospheric pollutants can be derived from telescopic measurements of the photometric extinction of stellar and local light sources in the visible wavelengths. An atmospheric model was developed which relates the broad-band extinction spectrum to the sum of the individual atmospheric constituent extinctions. To date the model includes constituents such as inversion layer ozone, nitrogen oxides, natural and photochemical aerosols, stratospheric ozone and aerosols, water vapor, and Rayleigh molecular absorption. The anomalous ''red hump'' in extinction appears to be explained. Mie scattering theory has been used to invert the aerosol spectral extinction results to produce particle size distribution curves. These distributions together with composition information have been used to infer the possible sources, such as automotive emission, combustion, marine aerosols, natural dirt, etc. Finally, high-resolution extinction spectroscopy has been undertaken to explore the species natural form of the photochemical species in the urban inversion layer. Some ideas are presented how each of these techniques can be used in an automated optical atmospheric monitoring station. (ERA citation 03:019697)