The objective of this work is to study the dynamics of aerosols in South America (Latitude 4°N-24°S and Longitude 83°W-33°W) from monthly averages images aerosol optical thickness (AOT) of 550 nm from the MODIS sensor (TERRA and AQUA) of period 2000 to 2012. We also will hope to using AOT in-situ data from six AERONET stations (Brazil: Rio Branco, Paraná JI, HIGH FORESTA, Campo Grande; Chile: Arica and Bolivia: Santa Cruz) for its validation with MODIS AOT products of period 2000 to 2011. The AOT products and time series were extracted from GIOVANNI software. We have analyzed several time series (MODIS-Terra, MODIS-Aqua and AERONET) for establishing the aerosol's temporal variability over the study area (Latitude 4°N-24°S and Longitude 83°W-33°W). On the one hand, we have found that the AOT data extracted from GIOVANNI show to oscillate between 0.0 to 0.6, having their maximum values during the months of August and September (between 0.45 and 0.5), over a period of thirteen years (2000-2012). This increase is consistent with the onset of fires by farmers in the Amazon region, which is very common during the aforementioned months.