Some urban and meteorological effects on the production of cloud condensation nuclei in Mexico City

Abstract

Series of ground-based measurements of cloud condensation nuclei (CCN) concentrations were performed at one-hour intervals near downtown Mexico City during nineteen days in the summer of-1985. The samplings were made with a cylindrical, thermal diffusion chamber operating at a fixed supersaturation of 0.75% and located 2 m above ground level. These data were analyzed in view of concurrent contaminant levels (NO, NO₂, and SO₂), aerosol particle concentrations and meteorological conditions, using information gathered by diverse agencies. The results indicate that the anthropogenic sources, along with the local meteorological conditions, determine the daily patterns of CCN concentrations in Mexico City.