Aircraft Sampling to Determine Atmospheric Concentrations and Size Distributionsof Particulate Matter and Other Pollutants Over the South Coast Air Basin

摘要

As part of the 1997 Southern California Ozone Study-North American ResearchStrategy for Tropospheric Ozone (SCOS97-NARSTO), a research aircraft was employed during August and September of 1997 to characterize the physical and chemical properties of the aerosol present over the Los Angeles Basin. Aerosol size distributions measured using a differential mobility analyzer and two optical partical counters were combined with filter based composition measurements to derive a physicochemical description of the aerosol sampled. The accuracy of this description was evaluated through comparison of derived and directly measured aerosol properties including mass, absorption coefficient, hemispherical backscattering coefficient, and total scattering coefficient at two different relative humidities. The sampled aerosol exhibited a complex vertical structure possessing multiple elevated aerosol layers. The most pronounced of these layers were observed to form by injection of aerosol above the ground-level mixed layer along the southern edge of the San Gabriel Mountains.