Espessuras ópticas de aerossóis de uma região rural do estado do Rio Grande do Sul comparadas com uma região industrial do Brasil

Abstract

Aerosols are solid or liquid particles suspended in air, which directly and indirectly interact with solar radiation and can be monitored through its optical depth. The aims of this study was to analyze the time series of Aerosol Optical Depth (AOD) on São Martinho da Serra, RS and compare them with São Paulo. The AOD of São Martinho da Serra, RS were obtained by Brewer Spectrophotometer (29.44 ° S, 53.82 ° W), from 1992 to 2008, using the Langley method at wavelengths: 306.3, 310.1, 313, 5, 316.7, 320.1 nm. Values above the mean plus standard deviation were considered peaks of aerosol. Was analyzed the behavior of the EOA to São Martinho da Serra, by the MODIS sensor (TERRA and AQUA satellites), the AERONET sun photometer and Brewer, being compared with the AERONET AOD of São Paulo (large industrial area). Satellite images were generated for verification of burning and air mass trajectories (HYSPLIT model). Over 70% of The AOD on São Martinho were below 0,3. Any aerosol peaks were identified with values above 0.31, which can be attributed to high relative humidity (fog formation) and the burned sites (November to February) and/or remote (August to October - an increase of burned in Brazil). In the days 06/09/2007 and 22/08/2010, was observed the transport of pollutants from the center of Brazil to RS, with AOD of up to 1.9. As for instruments, Brewer presented a behavior similar to MODIS AOD (which recorded absolute values lower). The AERONET, absolute values recorded near the MODIS (wavelengths near) and better behavior. Sao Paulo recorded AOD bigger than São Martinho, perhaps influenced by the various sources of pollutants in the region. Although São Martinho has low AOD, days with peak aerosols were recorded, concluding that, even away from urban centers, the region isn t free of high concentrations of aerosols.