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@ARTICLE{Geyer:33381,
author = {Geyer, A. and Bächmann, K. and Hofzumahaus, A. and
Holland, F. and Konrad, S. and Klüpfel, T. and Pätz, H.-W.
and Perner, C. R. and Mihelcic, D. and Schäfer, H.-J. and
Volz-Thomas, A. and Platt, U.},
title = {{N}ighttime formation of peroxy and hydroxyl radicals
during the {BERLIOZ} campaign - observations and modeling
studies},
journal = {Journal of Geophysical Research},
volume = {108},
issn = {0148-0227},
address = {Washington, DC},
publisher = {Union},
reportid = {PreJuSER-33381},
pages = {D4},
year = {2003},
note = {Record converted from VDB: 12.11.2012},
abstract = {[1] Traditionally, tropospheric radical chemistry is
discussed in terms of the daytime photochemically produced
hydroxyl radical (OH). Radicals, however, are also important
during nighttime: this is especially true for ozone and the
nitrate radical (NO3), which both act as key initiators of
the degradation of alkenes such as biogenic monoterpenes.
These reactions lead to the formation of peroxy radicals
(HO2 and RO2) and hydroxyl radicals at night. We present
recent observations of nighttime concentrations of NO3, RO2,
HO2, and OH by differential optical absorption spectroscopy
(DOAS), matrix isolation electron spin resonance (MIESR),
laser-induced fluorescence (LIF), and a chemical amplifier
(CA) in the framework of the Berliner Ozonexperiment
(BERLIOZ) campaign at Pabstthum, Germany, together with
modeling studies of nocturnal radical chemistry. Modeled RO2
mixing ratios reached 40 ppt while the measured ROx level
went up to 22 ppt at the same time. Modeled and measured HO2
mixing ratios were up to 6 and 4 ppt, respectively. In the
case of OH, a nocturnal concentration of (1.85 +/- 0.82) x
10(5) cm(-3) was measured during one night. At this time,
the model yielded an OH level of (4.1 +/- 0.7) x 10(5)
cm(-3). This overestimation by the model could point to a
missing nocturnal sink of OH. Nitrate radical reactions with
terpenes were found responsible for producing $77\%$ of the
RO2 radicals, $53\%$ of the HO2, and $36\%$ of the OH
radicals during night. Nighttime ozonolysis formed $12\%$ of
the RO2, $47\%$ of the HO2, and $64\%$ of the OH radicals.
Another $11\%$ of the RO2 radicals were formed by
OH-volatile organic compound (VOC) reactions. A positive
linear correlation of RO2 and NO3 was observed and could be
reproduced in model calculations originating from the loss
of both radicals by reaction with NO and the NO3-initiated
RO2 production. The contribution of nighttime OH to the
atmosphere's oxidation capacity (oxidation rate of VOCs, CO,
and CH4) was found negligible $(<0.5\%).$},
keywords = {J (WoSType)},
cin = {ICG-II},
ddc = {550},
cid = {I:(DE-Juel1)VDB48},
pnm = {Chemie und Dynamik der Geo-Biosphäre},
pid = {G:(DE-Juel1)FUEK257},
shelfmark = {Meteorology $\&$ Atmospheric Sciences},
typ = {PUB:(DE-HGF)16},
UT = {WOS:000181827100001},
doi = {10.1029/2001JD000656},
url = {https://juser.fz-juelich.de/record/33381},
}