HIGH-RESOLUTION AIR QUALITY MODELLING OF A TRACE GAS (CO) IN MANIZALES, COLOMBIA. ANALYSIS OF DIFFERENCES BETWEEN TWO CHEMICAL MECHANISMS

Atmospheric modeling is an essential tool for studying the impacts and dynamics of gases and aerosols on air quality. The use of eulerian 3-D chemistry transport models (CTM) have been recognized as a powerful tool for simulating reactive pollutants in urban environments, not only for its capacity to include aerosol and chemical mechanisms, but also for simulating the coupled effects of meteorology on the complex dynamic of urban air pollution. The implementation of CTM is a challenging task, especially in cities dominated by a complex topography and small area of development, factor which implies a high-resolution simulation. Furthermore, different studies have recognized that the use of local atmospheric emission fluxes into the model is essential for obtaining a more accurate representation of the modeled period. The use of CTM in Colombian cities is scarce and have been focused mainly on large cities such as Bogotá and Medellin. In medium-sized cities, only the city of Manizales reported previously a first approximation using the WRF-Chem CTM for studying the influence of anthropogenic emission sources (vehicular + industrial) in ozone (O3) dynamics. Conclusions obtained highlighted the necessity for performing new simulations analyzing other important trace gases such as carbon monoxide (CO), and to evaluate other chemical mechanisms for defining the best model configuration. This work aimed to study the dynamic of CO anthropogenic emissions and its dispersion patterns in the medium-sized Andean city of Manizales, Colombia, using the eulerian WRF-Chem model. Furthermore, differences in representation of CO from the application of two chemical mechanisms (RADM and CBMZ) were analyzed. Two high-resolution (1 km) model simulations were performed incorporating local emission fluxes of criteria pollutants, NMVOC and aerosols (PM10 and PM2.5). Results were compared with hourly measurements of CO, obtained currently in the air quality monitoring system of the city. This study provided a baseline for a current project performed in the city which seeks to define the best configuration for applying the modeling system WRF-Chem; searching not only an accurate modeling system for analyzing and understanding historic pollution episodes; but also to perform in the future air quality forecast simulations