Particle scattering coefficient, aerosol species contributions

To test the applicability of statistical techniques for determination of the species contributions to the scattering coefficient, a one-year study was conducted in 1979 at China Lake, California. Filter samples of aerosol particles smaller than 2 ym aerodynamic diameter were analyzed for total fine mass, major chemical species, and the time average particle absorption coefficient, bg. At the same time and location, bgp was measured with a sensitive nephelometer. A total of 61 samples were analyzed. Multiple regression analysis was applied to the average particle scattering coefficient and mass concentrations for each filter sample to estimate aj and each species contribution to light scattering, bgn-j. Supplementary measurements of the chemical-size distribution were used for theoretical estimates of each b pj as a test of the effectiveness of the statistical approach. 

The average contribution of each major aerosol species to the 1979 average particle scattering coefficient, Fsoi at China Lake, was calculated using the following relationship ... 

Aerosol Species Contributions to the Particle Scattering Coefficient Comparison of Statistical and Theoretical Results for China Lake ... 

Multiple regression analysis was applied to the measured particle scattering coefficient and fine aerosol species mass concentrations from 61 filter samples collected at China Lake, California in 1979. Contributions of various aerosol species to the particle scattering coefficient were estimated. 

The quality of statistically inferred species extinction balances can be enhanced with proper aerosol sampling. Due to its important role in light scattering, only the fine aerosol should be sampled. A mass balance should account for all major fine particle species. Ideally the particle scattering coefficient should be measured directly at the location where aerosol is sampled by the filters. The importance of soot and other carbonaceous aerosol contributions to light extinction in arid regions should not be overlooked. 

One must first link the source tb concentrations of each chemical species in the aerosol. Second, the contribution of each chemical species to the particle scattering and absorption coefficients must be determined. 

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