Numerical investigation of meteorological conditions leading to elevated ozone concentrations in Medellin, Colombia

Air pollution caused by motor vehicles is a major environmental problem in many Latin American urban areas. If appropriate measures are not taken soon, vehicular air pollution in the region is likely to worsen, posing a great threat to human health and welfare. Medellin, capital of the Antioquia department is located in the northwest of Colombia, 1, 538m above sea level in a high valley of the central mountains. It is the centre of the country's textile businesses and is primarily an industrial and commercial area. Medellin is considered to be the second most important city in Colombia. This paper deals with the application of the core model of the European Zooming Model (Moussiopoulos, 1995), namely the non-hydrostatic mesoscale model MEMO (Kunz and Moussiopoulos, 1995) to Medellin, Colombia with the aim to investigate meteorological conditions leading to elevated ozone concentrations. October 26, 1999 was chosen for model application as high ozone concentrations were recorded on that day and on the previous day it rained at Medellin and consequently, airborne pollutants were depleted from the atmosphere due to the washout process. Therefore, it is reasonable to assume that the atmosphere was initially clean on the beginning of the next day, e.g. high pollutant concentrations recorded on October 26 did not contain aged background values. In lack of regional scale model results, by this assumption substantial uncertainties, that are inherent to the estimation of background concentration values, are avoided.