Modelling of air pollution dispersion in Santiago de Chile

In Santiago de Chile air quality standards are frequently exceeded during both summer and winter time. The evaluation of the temporal and spatial evolution of the chemical and physical characteristics of these air pollution problems requires the application of three-dimensional models. In this work, the Chilean Air Pollution Dispersion Model (CADM), a three-dimensional Eulerian chemical transport model is presented. The model is applied for the simulation of air pollution dispersion during summer. Carbon monoxide (CO) dispersion is studied in order to evaluate advection and diffusion as simulated by CADM and to characterise dispersion patterns in the Santiago basin. Horizontal and vertical dispersion patterns are presented, explaining how pollutants are ventilated out of the Santiago basin. Also, the role of turbulence on the pollutant distribution is discussed. Furthermore, an attempt is made to explain how pollutants are accumulated in the basin during night in the nocturnal stable planetary boundary layer and what mechanisms affect the transport of pollutants under these conditions. Comparing results from model simulations with observations, it can be shown that the model is able to represent the diurnal cycles of CO reasonably well. It can be concluded that CADM is suited for the application of air pollution dispersion in the Santiago basin in particular and complex terrain in general.