From Gray to Green: An Aerosol Journey in the Amazon
Surrounded by the Amazon rainforest, aircraft measurements from the urban plume over Manaus, Brazil, reveal the life cycle of organic aerosol
Aerosols—tiny particles in the air—have important effects on the Earth's energy balance and water cycle. The majority of the aerosol mass is made up of organic compounds that formed from precursor compounds released by plants and human activities. Understanding how precursor compounds evolve in the atmosphere and eventually end up as aerosol particles, and representing these processes in models, is one of the more complex challenges in atmospheric science.
Using airborne data from the Green Ocean Amazon (GoAmazon 2014/5) field campaign, a research team led by scientists at the U.S. Department of Energy's (DOE) Pacific Northwest National Laboratory collected and analyzed measurements of the chemical composition, sources, and evolution of aerosol in the urban plume from Manaus, Brazil, as it moved into the surrounding pristine Amazon tropical forest. The data analysis showed changes in the aerosol chemical properties as the plume moved downwind. The measurements also suggested that formation of organic aerosol in the Manaus plume occurred, at least in part, by a mechanism different from that seen in pollution from North American cities.
Measurements obtained from the DOE Atmospheric Radiation Measurement (ARM) user facility'sGulfstream-159 (G-1) research aircraft during GoAmazon provide a unique set of observations for understanding aerosol chemistry. When compared to the outflow of many North American cities, the team's analysis showed that, in the wet season, aging of the Manaus plume generated less organic aerosol downwind. These results have implications for modeling efforts and for understanding how urban pollution evolves in unique environments and affects the Amazon rainforest.
Reference: J.E. Shilling, M.S. Pekour, E.C. Fortner, P. Artaxo, S. de Sá, J.M. Hubbe, K.M. Longo, L.A.T. Machado, S.T. Martin, S.R. Springston, J. Tomlinson, J. Wang, "Aircraft Observations of the Chemical Composition and Aging of Aerosol in the Manaus Urban Plume during GoAmazon 2014/5." Atmospheric Chemistry and Physics 18, 10773-10797 (2018). [https://doi.org/10.5194/acp-18-10773-2018]
Published: September 6, 2018