High time resolution observation and statistical analysis of atmospheric light extinction properties and the chemical speciation of fine particulates

In recent years, the visibility deterioration caused by regional fine particulate pollution becomes one of the crucial air pollution problems in the urban areas of our country. The rapid variation of visibility and fine particulates make it difficult to estimate the relationship between them precisely and accurately unless high time resolution observation data can be accessed. This study aims to fill this gap in the field of atmospheric science by establishing a formula using multiple linear regressions. Excellent fitting goodness (R-2=0.913, n=3167) was obtained using 10 min average of high-resolution real-time light scattering coefficients, light absorption coefficients, main chemical speciation concentration in PM1 and some meteorological parameters from 17 Jan to 16 Feb, 2009. It shows that the average light extinction coefficient during the observation in the winter of Shenzhen was measured to be 290 +/- 183 Mm(-1), consisting of 72% of light scattering and 21% of absorption. In terms of the percentage contribution of PM1 chemical species to the total light extinction, the organic matter was estimated to be most with an average of 45%, followed by ammonium sulfate with an average of 24%. The contributions of black carbon and ammonium nitrate were 17% and 12%, respectively. Besides, the diurnal variation of light extinction was investigated as well in this study.