Influx of African biomass burning aerosol during the Amazonian dry season through layered transatlantic transport of black carbon-rich smoke

Author(s):Show less -

Holanda, Bruna A. ^{[1, 2, 3]} ; Poehlker, Mira L. ^[3] ; Walter, David ^{[3, 4]} ; Saturno, Jorge ^{[2, 5]} ; Soergel, Matthias ^{[2, 6]} ; Ditas, Jeannine ^{[3, 7]} ; Ditas, Florian ^{[2, 3, 8]} ; Schulz, Christiane ^{[9, 10]} ; Franco, Marco Aurelio ^{[1, 3]} ; Wang, Qiaoqiao ^{[2, 7]} ; Donth, Tobias ^[11] ; Artaxo, Paulo ^[1] ; Barbosa, Henrique M. J. ^[1] ; Borrmann, Stephan ^{[9, 12]} ; Braga, Ramon ^[3] ; Brito, Joel ^{[1, 13]} ; Cheng, Yafang ^[3] ; Dollner, Maximilian ^{[14, 15]} ; Kaiser, Johannes W. ^{[6, 16]} ; Klimach, Thomas ^[3] ; Knote, Christoph ^[17] ; Krueger, Ovid O. ^[3] ; Fuetterer, Daniel ^[15] ; Lavric, V, Jost ; Ma, Nan ^{[3, 7]} ; Machado, Luiz A. T. ^{[18, 3]} ; Ming, Jing ^{[2, 3]} ; Morais, Fernando G. ^[1] ; Paulsen, Hauke ^[3] ; Sauer, Daniel ^[15] ; Schlager, Hans ^[15] ; Schneider, Johannes ^[9] ; Su, Hang ^[3] ; Weinzierl, Bernadett ^{[14, 15]} ; Walser, Adrian ^{[17, 14, 15]} ; Wendisch, Manfred ^[11] ; Ziereis, Helmut ^[15] ; Zoeger, Martin ^[19] ; Poeschl, Ulrich ^[3] ; Andreae, Meinrat O. ^{[2, 20]} ; Poehlker, Christopher ^{[2, 3]}

Affiliation:Show less -

^[1] Univ Sao Paulo, Inst Fis, BR-05508090 Sao Paulo, SP - Brazil

^[2] Max Planck Inst Chem, Biogeochem Dept, D-55128 Mainz - Germany

^[3] Max Planck Inst Chem, Multiphase Chem Dept, D-55128 Mainz - Germany

^[4] V, Max Planck Inst Biogeochem, D-07701 Jena - Germany

^[5] Phys Tech Bundesanstalt, D-38116 Braunschweig - Germany

^[6] Max Planck Inst Chem, Atmospher Chem Dept, D-55128 Mainz - Germany

^[7] Jinan Univ, Inst Environm & Climate Res ECI, Guangzhou 511443 - Peoples R China

^[8] Hessisches Landesamt Nat Schutz Umwelt & Geol, D-65203 Wiesbaden - Germany

^[9] Max Planck Inst Chem, Particle Chem Dept, D-55128 Mainz - Germany

^[10] Leibniz Inst Tropospher Res, Expt Aerosol & Cloud Microphys Dept, TROPOS, Leipzig - Germany

^[11] Univ Leipzig, Leipzig Inst Meteorol, Leipzig - Germany

^[12] Johannes Gutenberg Univ Mainz, Inst Phys Atmosphere, D-55128 Mainz - Germany

^[13] Univ Lille, SAGE, IMT Lille Douai, F-59000 Lille - France

^[14] Univ Vienna, Fac Phys Aerosol Phys & Environm Phys, A-1090 Vienna - Austria

^[15] German Aerosp Ctr DLR, Inst Atmospher Phys, D-82234 Oberpfaffenhofen - Germany

^[16] Deutsch Wetterdienst, D-63067 Offenbach - Germany

^[17] Ludwig Maximilians Univ Munchen, Meteorol Inst, Munich - Germany

^[18] Natl Inst Space Res INPE, Sao Jose Dos Campos - Brazil

^[19] German Aerosp Ctr DLR, Flight Expt, D-82234 Oberpfaffenhofen - Germany

^[20] Univ Calif San Diego, Scripps Inst Oceanog, La Jolla, CA 92093 - USA

• Document type: Journal article
• Source: Atmospheric Chemistry and Physics; v. 20, n. 8, p. 4757-4785, APR 24 2020.
• Web of Science Citations: 0

Abstract

Black carbon (BC) aerosols influence the Earth's atmosphere and climate, but their microphysical properties, spatiotemporal distribution, and long-range transport are not well constrained. This study presents airborne observations of the transatlantic transport of BC-rich African biomass burning (BB) smoke into the Amazon Basin using a Single Particle Soot Photometer (SP2) as well as several complementary techniques. We base our results on observations of aerosols and trace gases off the Brazilian coast onboard the HALO (High Altitude and LOng range) research aircraft during the ACRIDICON-CHUVA campaign in September 2014. During flight AC19 over land and ocean at the northeastern coastline of the Amazon Basin, we observed a BCrich layer at similar to 3.5 km altitude with a vertical extension of similar to 0.3 km. Backward trajectories suggest that fires in African grasslands, savannas, and shrublands were the main source of this pollution layer and that the observed BB smoke had undergone more than 10 d of atmospheric transport and aging over the South Atlantic before reaching the Amazon Basin. The aged smoke is characterized by a dominant accumulation mode, centered at about 130 nm, with a particle concentration of N-acc = 850 +/- 330 cm(-3). The rBC particles account for similar to 15% of the submicrometer aerosol mass and similar to 40% of the total aerosol number concentration. This corresponds to a mass concentration range from 0.5 to 2 mu gm(-3) (1st to 99th percentiles) and a number concentration range from 90 to 530 cm(-3). Along with rBC, high cCO (150 +/- 30 ppb) and cO3 (56 +/- 9 ppb) mixing ratios support the biomass burning origin and pronounced photochemical aging of this layer. Upon reaching the Amazon Basin, it started to broaden and to subside, due to convective mixing and entrainment of the BB aerosol into the boundary layer. Satellite observations show that the transatlantic transport of pollution layers is a frequently occurring process, seasonally peaking in August/September. By analyzing the aircraft observations together with the long-term data from the Amazon Tall Tower Observatory (ATTO), we found that the transatlantic transport of African BB smoke layers has a strong impact on the northern and central Amazonian aerosol population during the BB-influenced season (July to December). In fact, the early BB season (July to September) in this part of the Amazon appears to be dominated by African smoke, whereas the later BB season (October to December) appears to be dominated by South American fires. This dichotomy is reflected in pronounced changes in aerosol optical properties such as the single scattering albedo (increasing from 0.85 in August to 0.90 in November) and the BC-to-CO enhancement ratio (decreasing from 11 to 6 ngm 3 ppb 1). Our results suggest that, despite the high fraction of BC particles, the African BB aerosol acts as efficient cloud condensation nuclei (CCN), with potentially important implications for aerosol-cloud interactions and the hydrological cycle in the Amazon. (AU)

• FAPESP's process: 17/17047-0 - Aerosol and clouds life cycles in Amazonia: biogenic emissions, biomass burning and impacts on ecosystem
• Grantee: Paulo Eduardo Artaxo Netto
• Support Opportunities: Research Program on Global Climate Change - Thematic Grants