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@ARTICLE{Schulz:852463,
      author       = {Schulz, Christiane and Schneider, Johannes and Amorim
                      Holanda, Bruna and Appel, Oliver and Costa, Anja and de Sá,
                      Suzane S. and Dreiling, Volker and Fütterer, Daniel and
                      Jurkat-Witschas, Tina and Klimach, Thomas and Krämer,
                      Martina and Martin, Scot T. and Mertes, Stephan and
                      Pöhlker, Mira L. and Sauer, Daniel and Voigt, Christiane
                      and Weinzierl, Bernadett and Ziereis, Helmut and Zöger,
                      Martin and Andreae, Meinrat O. and Artaxo, Paulo and
                      Machado, Luiz A. T. and Pöschl, Ulrich and Wendisch,
                      Manfred and Borrmann, Stephan},
      title        = {{A}ircraft-based observations of isoprene epoxydiol-derived
                      secondary organic aerosol ({IEPOX}-{SOA}) in the tropical
                      upper troposphere over the {A}mazon region},
      journal      = {Atmospheric chemistry and physics / Discussions},
      volume       = {-},
      issn         = {1680-7375},
      address      = {Katlenburg-Lindau},
      publisher    = {EGU},
      reportid     = {FZJ-2018-05409},
      pages        = {1 - 32},
      year         = {2018},
      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
                      height up to 14.4km. 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, leading to increased organic aerosol mass
                      concentrations above 10km altitude. The median organic mass
                      concentrations in the upper troposphere above 10km range
                      between 1.0 and 2.1μgm−3 (referring to standard
                      temperature and pressure; STP) with interquartile ranges of
                      0.6 to 3.0μgm−3 (STP), representing $70\%$ of the total
                      submicron non-refractory aerosol particle mass. The presence
                      of isoprene epoxydiol-derived isoprene 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 upper troposphere 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 pre-existing
                      particles leads to IEPOX-SOA formation and subsequently
                      increasing organic mass in the upper troposphere. This
                      organic mass increase was accompanied by an increase of the
                      nitrate mass concentrations, most likely due to NOx
                      production by lightning. We further found that the ammonium
                      contained in the aerosol particles is not sufficient to
                      neutralize the particulate sulfate and nitrate. Analysis of
                      the ion ratio of NO+ to NO2+ indicated that nitrate in the
                      upper troposphere 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 upper
                      troposphere either on acidic nitrate particles forming
                      organic nitrates derived from IEPOX or on already
                      neutralized organic nitrate aerosol particles.},
      cin          = {IEK-7},
      ddc          = {550},
      cid          = {I:(DE-Juel1)IEK-7-20101013},
      pnm          = {244 - Composition and dynamics of the upper troposphere and
                      middle atmosphere (POF3-244)},
      pid          = {G:(DE-HGF)POF3-244},
      typ          = {PUB:(DE-HGF)16},
      doi          = {10.5194/acp-2018-232},
      url          = {https://juser.fz-juelich.de/record/852463},
}