Submicron particles in an urban atmosphere: A study of optical size distributions—I

Abstract Atmospheric particle size distributions and number concentrations in the 0.065–0.900 μm diameter range have been observed at a site in the city of Santiago de Chile from June 1992 to December 1994 by means of an active light-scattering spectrometer; such information was not previously available. Observed concentrations ranged from 2000 to 16,000 per cm 3 . Geometric mean diameters (GMD) for the distributions ranged from 0.100 to 0.160 μm, while geometric standard deviations (GSD) ranged from 1.34 to 1.65 and volume-weighted mean diameters (VWD) ranged from 0.18 to 0.42 μm Scatter plots and time-ordered sequences for these parameters are shown as well as Spearman rank-difference correlations. Examples of the particle-number concentration distributions and of daily concentration trends are displayed and discussed.