Ground-based observation of clusters and nucleation-mode particles in the Amazon

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Wimmer, Daniela ^[1] ; Mazon, Stephany Buenrostro ^[1] ; Manninen, Hanna Elina ^{[1, 2]} ; Kangasluoma, Juha ^[1] ; Franchin, Alessandro ^{[3, 1, 4]} ; Nieminen, Tuomo ^{[1, 5]} ; Backman, John ^[6] ; Wang, Jian ^[7] ; Kuang, Chongai ^[7] ; Krejci, Radovan ^[8] ; Brito, Joel ^{[9, 10]} ; Morais, Fernando Goncalves ^[10] ; Martin, Scot Turnbull ^[11] ; Artaxo, Paulo ^[10] ; Kulmala, Markku ^[1] ; Kerminen, Veli-Matti ^[1] ; Petaja, Tuukka ^[1]

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^[1] Univ Helsinki, Dept Phys, Gustaf Hallstromin Katu 2a, Helsinki 00560 - Finland

^[2] European Org Nucl Res CERN, CH-1211 Geneva - Switzerland

^[3] Univ Colorado, Cooperat Inst Res Environm Sci, Boulder, CO 80309 - USA

^[4] NOAA, ESRL, Chem Sci Div, Boulder, CO - USA

^[5] Univ Eastern Finland, Dept Appl Phys, POB 1627, Kuopio 70211 - Finland

^[6] Finnish Meteorol Inst, Atmospher Composit Res, Erik Palmenin Aukio 1, Helsinki 00560 - Finland

^[7] Brookhaven Natl Lab, Environm & Climate Sci Dept, Upton, NY 11973 - USA

^[8] Stockholm Univ, Dept Environm Sci & Analyt Chem ACES, S-10691 Stockholm - Sweden

^[9] Univ Clermont Auvergne, Lab Meteorol Phys LaMP, F-63000 Clermont Ferrand - France

^[10] Univ Sao Paulo, Inst Phys, Fis, Rua Matao 1371, BR-05508090 Sao Paulo - Brazil

^[11] Harvard Univ, Sch Engn & Appl Sci, Cambridge, MA 02138 - USA

• Tipo de documento: Artigo Científico
• Fonte: Atmospheric Chemistry and Physics; v. 18, n. 17, p. 13245-13264, SEP 14 2018.
• Citações Web of Science: 3

Resumo

We investigated atmospheric new particle formation (NPF) in the Amazon rainforest using direct measurement methods. To our knowledge this is the first direct observation of NPF events in the Amazon region. However, previous observations elsewhere in Brazil showed the occurrence of nucleation-mode particles. Our measurements covered two field sites and both the wet and dry season. We measured the variability of air ion concentrations (0.8-12 nm) with an ion spectrometer between September 2011 and January 2014 at a rainforest site (T0t). Between February and October 2014, the same measurements were performed at a grassland pasture site (T3) as part of the GoAmazon 2014/5 experiment, with two intensive operating periods (IOP1 and IOP2 during the wet and the dry season, respectively). The GoAmazon 2014/5 experiment was designed to study the influence of anthropogenic emissions on the changing climate in the Amazon region. The experiment included basic aerosol and trace gas measurements at the ground, remote sensing instrumentation, and two aircraft-based measurements. The results presented in this work are from measurements performed at ground level at both sites. The site inside the rainforest (T0t) is located 60 km NNW of Manaus and influenced by pollution about once per week. The pasture (T3) site is located 70 km downwind from Manaus and influenced by the Manaus pollution plume typically once per day or every second day, especially in the afternoon. No NPF events were observed inside the rainforest (site T0t) at ground level during the measurement period. However, rain-induced ion and particle bursts (hereafter, ``rain events{''}) occurred frequently (643 of 1031 days) at both sites during the wet and dry season, being most frequent during the wet season. During the rain events, the ion concentrations in three size ranges (0.8-2, 2-4, and 4-12 nm) increased up to about 10(4)-10(5) cm(-3). This effect was most pronounced in the intermediate and large size ranges, for which the background ion concentrations were about 10-15 cm(-3) compared with 700 cm(-3) for the cluster ion background. We observed eight NPF events at the pasture site during the wet season. We calculated the growth rates and formation rates of neutral particles and ions for the size ranges 2-3 and 3-7 nm using the ion spectrometer data. The observed median growth rates were 0.8 and 1.6 nm h(-1) for 2-3 nm sized ions and particles, respectively, with larger growth rates (13.3 and 7.9 nm h(-1)) in the 3-7 nm size range. The measured nucleation rates were of the order of 0.2 cm(-3) s(-1) for particles and 4-9 x 10(-3) cm(-3) s(-1) for ions. There was no clear difference in the sulfuric acid concentrations between the NPF event days and nonevent days (similar to 9 x 10(5) cm(-3)). The two major differences between the NPF days and nonevent days were a factor of 1.8 lower condensation sink on NPF event days (1.8 x 10(-3) s(-1)) compared to nonevents (3.2 x 10(-3) s(-1)) and different air mass origins. To our knowledge, this is the first time that results from ground-based sub-3 nm aerosol particle measurements have been obtained from the Amazon rainforest. (AU)

• Processo FAPESP: 13/05014-0 - GoAmazon: interação da pluma urbana de Manaus com emissões biogênicas da Floresta Amazônica
• Beneficiário: Paulo Eduardo Artaxo Netto
• Modalidade de apoio: Auxílio à Pesquisa - Programa de Pesquisa sobre Mudanças Climáticas Globais - Temático