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@ARTICLE{Schulz:856664,
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 Knote,
Christoph and Krämer, Martina and Martin, Scot T. and
Mertes, Stephan and Pöhlker, Mira L. and Sauer, Daniel and
Voigt, Christiane and Walser, Adrian 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},
volume = {18},
number = {20},
issn = {1680-7324},
address = {Katlenburg-Lindau},
publisher = {EGU},
reportid = {FZJ-2018-06026},
pages = {14979 - 15001},
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
(BL) 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 (UT), leading to increased organic aerosol
mass concentrations above 10km altitude. The median organic
mass concentrations in the UT above 10km range between 1.0
and 2.5µgm−3 (referring to standard temperature and
pressure; STP) with interquartile ranges of 0.6 to
3.2µgm−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 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
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.},
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},
UT = {WOS:000447744000003},
doi = {10.5194/acp-18-14979-2018},
url = {https://juser.fz-juelich.de/record/856664},
}