Review status: a revised version of this preprint is currently under review for the journal ACP.
Aerosols from anthropogenic and biogenic sources and their
interactions: modeling aerosol formation, optical properties and
impacts over the central Amazon Basin
Janaína P. Nascimento1,Megan M. Bela5,6,Bruno Meller2,Alessandro L. Banducci8,Luciana V. Rizzo7,Angel Liduvino Vara-Vela4,Henrique M. J. Barbosa2,Helber Gomes9,10,Sameh A. A. Rafee3,Marco A. Franco2,Samara Carbone11,2,Glauber G. Cirino12,Rodrigo A. F. Souza1,Stuart A. McKeen5,6,and Paulo Artaxo2Janaína P. Nascimento et al.Janaína P. Nascimento1,Megan M. Bela5,6,Bruno Meller2,Alessandro L. Banducci8,Luciana V. Rizzo7,Angel Liduvino Vara-Vela4,Henrique M. J. Barbosa2,Helber Gomes9,10,Sameh A. A. Rafee3,Marco A. Franco2,Samara Carbone11,2,Glauber G. Cirino12,Rodrigo A. F. Souza1,Stuart A. McKeen5,6,and Paulo Artaxo2
1Post-graduate Program in Climate and Environment (CLIAMB), National Institute for Amazonian Research and Amazonas State University, Manaus, AM, Brazil
2Institute of Physics, University of Sao Paulo, Sao Paulo, SP, Brazil
3Department of Atmospheric Sciences, Institute of Astronomy, Geophysics and Atmospheric Sciences, University of São Paulo, SP, Brazil
4Center for Weather Forecasting and Climate Studies, National Institute for Space Research, Cachoeira Paulista, Sao Paulo, SP, Brazil
5Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO, USA
6NOAA Earth System Research Laboratory, Boulder, CO, USA
7Department of Environmental Sciences, Institute of Environmental, Chemical and Pharmaceutics Sciences, Federal University of Sao Paulo, Sao Paulo, SP, Brazil
8Department of Physics, Colorado State University, Fort Collins, CO, USA
9Institute of Atmospheric Sciences, Federal University of Alagoas, Maceió, AL, Brazil
10Department of Meteorology, Federal University of Campina Grande, Campina Grande, Brazil, PB, Brazil
11Federal University of Uberlândia, Uberlândia, MG, Brazil
12Department of Meteorology, Geosciences Institute, Federal University of Pará, PA, Brazil
1Post-graduate Program in Climate and Environment (CLIAMB), National Institute for Amazonian Research and Amazonas State University, Manaus, AM, Brazil
2Institute of Physics, University of Sao Paulo, Sao Paulo, SP, Brazil
3Department of Atmospheric Sciences, Institute of Astronomy, Geophysics and Atmospheric Sciences, University of São Paulo, SP, Brazil
4Center for Weather Forecasting and Climate Studies, National Institute for Space Research, Cachoeira Paulista, Sao Paulo, SP, Brazil
5Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO, USA
6NOAA Earth System Research Laboratory, Boulder, CO, USA
7Department of Environmental Sciences, Institute of Environmental, Chemical and Pharmaceutics Sciences, Federal University of Sao Paulo, Sao Paulo, SP, Brazil
8Department of Physics, Colorado State University, Fort Collins, CO, USA
9Institute of Atmospheric Sciences, Federal University of Alagoas, Maceió, AL, Brazil
10Department of Meteorology, Federal University of Campina Grande, Campina Grande, Brazil, PB, Brazil
11Federal University of Uberlândia, Uberlândia, MG, Brazil
12Department of Meteorology, Geosciences Institute, Federal University of Pará, PA, Brazil
Received: 26 Sep 2020 – Accepted for review: 28 Oct 2020 – Discussion started: 19 Nov 2020
Abstract. The Green Ocean Amazon experiment – GoAmazon2014/5 explored the interactions between natural biogenic forest emissions from Central Amazonia and urban air pollution from Manaus. Previous GoAmazon2014/5 studies showed that nitrogen oxides (NOx = NO + NO2) and sulfur oxides (SOx) emissions from Manaus strongly interact with biogenic volatile organic compounds (BVOCs), affecting secondary organic aerosol (SOA) formation. In previous studies, ground based and aircraft measurements provided evidence of SOA formation and strong changes in aerosol composition and properties. Aerosol optical properties also evolve, and their impacts on the Amazonian ecosystem can be significant. As particles age, some processes such as SOA production, black carbon (BC) deposition, particle growth, and the BC lensing effect change the aerosol optical properties, affecting the solar radiation flux at the surface. This study analyzes data and models SOA formation using the Weather Research and Forecasting with Chemistry (WRF-Chem) model to assess the spatial variability of aerosol optical properties as the Manaus plumes interact with the natural atmosphere. The following aerosol optical properties are investigated: single scattering albedo (SSA), asymmetry parameter (gaer), absorption Ångström exponent (AAE), and scattering Ångström exponent (SAE). These simulations were validated using ground based measurements at three experimental sites: Amazon Tall Tower Observatory – ATTO (T0a), downtown Manaus (T1), Tiwa Hotel (T2) and Manacapuru (T3), as well as the G1 aircraft flights. WRF-Chem simulations were performed over seven days during March 2014. Results show a mean biogenic SOA (BSOA) mass enrichment of 512 % at the T1 site, 450 % in regions downwind of Manaus such as the T3 site and 850 % in areas north of the T3 site in simulations with anthropogenic emissions. The SOA formation is rather fast, with about 80 % of the SOA mass produced in 3–4 hours. Comparing the plume from simulations with and without anthropogenic emissions, SSA shows a downwind reduction of approximately 10 %, 11 % and 6 % at the T1, T2 and T3 sites, respectively. Other regions, such as those further downwind of the T3 site, are also affected. Gaer values increased from 0.62 to 0.74 at the T1 site and from 0.67 to 0.72 at the T3 site when anthropogenic emissions are active. During the Manaus plume aging process, a plume tracking analysis shows an increase in SSA from 0.91 close to Manaus to 0.98 160 km downwind of Manaus as a result of SOA production and BC deposition.