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

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 cm3. 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.