Aircraft-based observations of isoprene-epoxydiol-derived secondary organic aerosol (IEPOX-SOA) in the tropical upper troposphere over the Amazon region

Author(s):Show less -

Schulz, Christiane ^{[1, 2, 3]} ; Schneider, Johannes ^{[1, 2, 3]} ; Holanda, Bruna Amorim ^{[1, 2, 3]} ; Appel, Oliver ^{[1, 2, 3]} ; Costa, Anja ^[4] ; de Sa, Suzane S. ^[5] ; Dreiling, Volker ^[6] ; Fuetterer, Daniel ^[7] ; Jurkat-Witschas, Tina ^[7] ; Klimach, Thomas ^{[1, 2, 3]} ; Knote, Christoph ^[8] ; Kraemer, Martina ^[4] ; Martin, Scot T. ^{[5, 9]} ; Mertes, Stephan ^[10] ; Poehlker, Mira L. ^{[1, 2, 3]} ; Sauer, Daniel ^[7] ; Voigt, Christiane ^{[11, 7]} ; Walser, Adrian ^{[8, 7, 12]} ; Weinzierl, Bernadett ^{[7, 12]} ; Ziereis, Helmut ^[7] ; Zoeger, Martin ^[6] ; Andreae, Meinrat O. ^{[1, 13, 2, 3]} ; Artaxo, Paulo ^[14] ; Machado, Luiz A. T. ^[15] ; Poeschl, Ulrich ^{[1, 2, 3]} ; Wendisch, Manfred ^[16] ; Borrmann, Stephan ^{[1, 2, 3, 11]}

Affiliation:Show less -

^[1] Max Planck Inst Chem, Biogeochem Dept, Mainz - Germany

^[2] Max Planck Inst Chem, Multiphase Chem Dept, Mainz - Germany

^[3] Max Planck Inst Chem, Particle Chem Dept, Mainz - Germany

^[4] Forschungszentrum Julich, Inst Energie & Klimaforsch IEK7, Julich - Germany

^[5] Harvard Univ, Sch Engn & Appl Sci, Cambridge, MA 02138 - USA

^[6] German Aerosp Ctr, Deutsch Zentrum Luft & Raumfahrt, Flight Expt, Oberpfaffenhofen - Germany

^[7] German Aerosp Ctr, Deutsch Zentrum Luft & Raumfahrt, Inst Atmospher Phys, Oberpfaffenhofen - Germany

^[8] Ludwig Maximilians Univ Munchen, Meteorol Inst, Munich - Germany

^[9] Harvard Univ, Dept Earth & Planetary Sci, 20 Oxford St, Cambridge, MA 02138 - USA

^[10] Leibniz Inst Tropospher Res, Leipzig - Germany

^[11] Johannes Gutenberg Univ Mainz, Inst Phys Atmosphere, Mainz - Germany

^[12] Univ Vienna, Fac Phys, Vienna - Austria

^[13] Univ Calif San Diego, Scripps Inst Oceanog, La Jolla, CA 92093 - USA

^[14] Univ Sao Paulo, Inst Fis, Sao Paulo - Brazil

^[15] INPE, Ctr Previsdo Tempo & Estudos Climat, Sao Jose Dos Campos - Brazil

^[16] Univ Leipzig, Leipzig Inst Meteorol, Leipzig - Germany

• Document type: Journal article
• Source: Atmospheric Chemistry and Physics; v. 18, n. 20, p. 14979-15001, OCT 18 2018.
• Web of Science Citations: 2

Abstract

During the ACRIDICON-CHUVA field project (September-October 2014; based in Manaus, Brazil) aircraft-based in situ measurements of aerosol chemical composition were conducted in the tropical troposphere over the Amazon using the High Altitude and Long Range Research Aircraft (HALO), covering altitudes from the boundary layer (BL) height up to 14.4 km. The submicron non-refractory aerosol was characterized by flash-vaporization/electron impact-ionization aerosol particle mass spectrometry. The results show that significant secondary organic aerosol (SOA) formation by isoprene oxidation products occurs in the upper troposphere (UT), leading to increased organic aerosol mass concentrations above 10 km altitude. The median organic mass concentrations in the UT above 10 km range between 1.0 and 2.5 mu g m(-3) (referring to standard temperature and pressure; STP) with interquartile ranges of 0.6 to 3.2 mu g m(-3) (STP), representing 78 % of the total submicron non-refractory aerosol particle mass. The presence of isoprene-epoxydiol-derived secondary organic aerosol (IEPOX-SOA) was confirmed by marker peaks in the mass spectra. We estimate the contribution of IEPOX-SOA to the total organic aerosol in the UT to be about 20 %. After isoprene emission from vegetation, oxidation processes occur at low altitudes and/or during transport to higher altitudes, which may lead to the formation of IEPOX (one oxidation product of isoprene). Reactive uptake or condensation of IEPOX on preexisting particles leads to IEPDX-SOA formation and subsequently increasing organic mass in the UT. This organic mass increase was accompanied by an increase in the nitrate mass concentrations, most likely due to NOx production by lightning. Analysis of the ion ratio of NO+ to NO2+ indicated that nitrate in the UT exists mainly in the form of organic nitrate. IEPOX-SOA and organic nitrates are coincident with each other, indicating that IEPDX-SOA forms in the UT either on acidic nitrate particles forming organic nitrates derived from IEPDX or on already neutralized organic nitrate aerosol particles. (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
• FAPESP's process: 13/05014-0 - GoAmazon: interactions of the urban plume of Manaus with biogenic forest emissions in Amazonia
• Grantee: Paulo Eduardo Artaxo Netto
• Support Opportunities: Research Program on Global Climate Change - Thematic Grants