04/19/2016

Pollution from a Megacity in the Amazon

Two-year field campaign allows unprecedented study of anthropogenic influences on aerosols, clouds, and convective precipitation.

The Science

Recent field campaign research in the Amazon sought to quantify how aerosol and cloud lifecycles in a clean background in the tropics are influenced by pollutant outflow from a large tropical city. The team used ground-based research sites and aircraft measurement systems in wet and dry seasons in the environs of Manaus, Brazil, for the study.

The Impact

The experiment takes advantage of the natural laboratory represented by the Amazon rainforest’s pristine environment as influenced by pollutant outflow from a tropical megacity. The study is examining how aerosol and cloud lifecycles, including cloud-aerosol-precipitation interactions, are influenced by a range of anthropogenic influences otherwise unavailable. The findings will enable more accurate predictions, embedded in models, on how the present-day functioning of energy, carbon, and chemical flows in the Amazon basin might change, both due to global climate change and to past and projected economic development.

Summary

The Green Ocean Amazon field campaign sought to quantify and understand how aerosol and cloud lifecycles in a particularly clean background in the tropics were influenced by pollutant outflow from a large tropical city. The experiment was conducted by a large, multi-organization team, including scientists from both Brazilian and U.S. institutions, and was carried out in the environs of Manaus, Brazil, an isolated urban region of over 2 million people. The city is surrounded by a natural forest for over 1000 km in every direction. The city, encompassing a large industrial zone, uses high-sulfur oil as its primary fuel for electricity generation and emits large quantities of soot. Particle concentrations increase 10 to 100 times in the pollution plume compared to when pristine conditions prevail. The intersecting research sites downwind of Manaus oscillated between one of the least perturbed natural continental sites on Earth and one in which the pollution emissions of a tropical metropolis interact with the natural emissions of the rainforest. These findings will help researchers understand how aerosol and cloud lifecycles, including cloud-aerosol-precipitation interactions, are influenced by pollutant outflow from a tropical megacity. The goal is to provide data for a more accurate Earth system model to describe tropical regions and, in particular, the Amazon basin, where the hydrologic cycle is one of the primary heat engines of global circulation.

Principal Investigator(s)

Scot Martin
Harvard University, Cambridge, MA
[email protected]

Funding

Institutional support was provided by the Central Office of the Large Scale Biosphere Atmosphere Experiment in Amazonia (LBA), National Institute of Amazonian Research (INPA), National Institute for Space Research (INPE), Amazonas State University (UEA), and Brazilian Space Agency (AEB). The authors also acknowledge support from the U.S. Department of Energy (DOE), Office of Science, Office of Biological and Environmental Research, Atmospheric Radiation Measurement (ARM) Climate Research Facility, a user facility, and Atmospheric System Research (ASR) program. Funding was obtained from DOE, Amazonas State Research Foundation, São Paulo State Research Foundation, Brazil Scientific Mobility Program, U.S. National Science Foundation, German Max Planck Society, German Research Foundation, and German Aerospace Center. The research was conducted under scientific licenses 001030/2012-4, 001262/2012-2, and 00254/2013-9 of the Brazilian National Council for Scientific and Technological Development.

References

Martin, S. T., P. Artaxo, L. Machado, A. O. Manzi, R. A. Souza, C. Schumacher, J. Wang, M. O. Andreae, H. J. Barbosa, J. Fan, G. Fisch, A. H. Goldstein, A. Guenther, J. L. Jimenez, U. Poschl, M. A. Silva Dias, J. Smith, and M. Wendisch. 2016. “Introduction: Observations and Modeling of the Green Ocean Amazon (GoAmazon2014/15),” Atmospheric Chemistry and Physics 16, 4785-97. DOI: 10.5194/acp-16-4785-2016.