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

Schulz, C., Schneider, J., Holanda, B. A., Appel, O., Costa, A., de Sa, S. S., et al. (2018). Aircraft-based observations of isoprene-epoxydiol-derived secondary organic aerosol (IEPOX-SOA) in the tropical upper troposphere over the Amazon region. Atmospheric Chemistry and Physics, 18(20), 14979-15001. doi:10.5194/acp-18-14979-2018.

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Schulz, Christiane1, Author              
Schneider, Johannes1, Author              
Holanda, Bruna A.2, Author              
Appel, Oliver3, Author              
Costa, Anja4, Author
de Sa, Suzane S.4, Author
Dreiling, Volker4, Author
Fuetterer, Daniel4, Author
Jurkat-Witschas, Tina4, Author
Klimach, Thomas1, Author              
Knote, Christoph4, Author
Kraemer, Martina4, Author
Martin, Scot T.4, Author
Mertes, Stephan4, Author
Pöhlker, Mira L.2, Author              
Sauer, Daniel4, Author
Voigt, Christiane4, Author
Walser, Adrian4, Author
Weinzierl, Bernadett4, Author
Ziereis, Helmut4, Author
Zoeger, Martin4, AuthorAndreae, Meinrat O.2, Author              Artaxo, Paulo4, AuthorMachado, Luiz A. T.4, AuthorPöschl, Ulrich2, Author              Wendisch, Manfred4, AuthorBorrmann, Stephan1, Author               more..
1Particle Chemistry, Max Planck Institute for Chemistry, Max Planck Society, ou_1826291              
2Multiphase Chemistry, Max Planck Institute for Chemistry, Max Planck Society, ou_1826290              
3Max Planck Institute for Chemistry, Max Planck Society, ou_1826284              
4external, ou_persistent22              


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 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 µg m−3 (referring to standard temperature and pressure; STP) with interquartile ranges of 0.6 to 3.2 µg 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 IEPOX-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 NO+2 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 IEPOX-SOA forms in the UT either on acidic nitrate particles forming organic nitrates derived from IEPOX or on already neutralized organic nitrate aerosol particles.


Language(s): eng - English
 Dates: 2018
 Publication Status: Published in print
 Pages: -
 Publishing info: -
 Table of Contents: -
 Rev. Type: -
 Identifiers: ISI: 000447744000003
DOI: 10.5194/acp-18-14979-2018
 Degree: -



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Title: Atmospheric Chemistry and Physics
  Abbreviation : ACP
Source Genre: Journal
Publ. Info: Göttingen : Copernicus Publications
Pages: - Volume / Issue: 18 (20) Sequence Number: - Start / End Page: 14979 - 15001 Identifier: ISSN: 1680-7316
CoNE: https://pure.mpg.de/cone/journals/resource/111030403014016