Atmospheric Conditions That Favor Pollutant Concentrations in the South of Brazil

Abstract Significant concentrations of Total Suspended Particulate found in Rio Grande, in some years in the 90’s, were identified and their associated atmospheric conditions were applied to create a classification of situations that favor high pollutants’ concentrations. A hundred ten cases with concentrations above 30 μg.m-3 were detected and 53 out of those had concentrations above 75 μg.m-3. Events were grouped into 8 categories according to the similarity of the wind flow and the surface pressure field, based on the atmospheric fields obtained from Reanalysis data. Most cases take place when there is a high-pressure system south of, north of or over the region since it triggers moderate winds which do not enable pollutant dispersion. Data on weekly mean sea surface temperatures were also analyzed. When there is high pressure, there is a flow of cold waters coming from the south whereas, in low-pressure case, there is a flow of hot waters coming from the north. A satisfactory classification of atmospheric conditions that favor pollutant concentration in the city was carried out. An interaction between the ocean and the atmosphere was identified. This classification, along with the numerical weather forecast, may be used to warn population about the possibility of high pollutant concentrations.