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@BOOK{Gomm:155065,
author = {Gomm, Sebastian},
title = {{L}uftgestützte {M}essung von
{HO}$_{x}$-{R}adikalkonzentrationen mittels
{L}aser-induzierter {F}luoreszenz auf einem {Z}eppelin {NT}:
{U}ntersuchung der atmosphärischen {O}xidationsstärke der
unteren {T}roposphäre},
volume = {224},
school = {Universität Wuppertal},
type = {Dr.},
address = {Jülich},
publisher = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
reportid = {FZJ-2014-04250},
isbn = {978-3-89336-981-2},
series = {Schriften des Forschungszentrums Jülich, Reihe Energie
$\&$ Umwelt / Energy $\&$ Environment},
pages = {205 S.},
year = {2014},
note = {Universität Wuppertal, Diss., 2014},
abstract = {The OH radical is the major atmospheric oxidant that
dominates the photochemical degradationof trace gases and
pollutants in the atmosphere. The consumed OH can be
recycledthrough the HO$_{2}$ radical by reacting with NO,
thereby forming ozone. Thus, OH and HO$_{2}$ are ideal
parameter in order to test the current understanding of the
atmospheric degradation of trace gases. In this work, an
instrument for the measurement of OH and HO$_{2}$ radicals
by laser induced fluorescence was developed and deployed on
board a Zeppelin NT. The measurements presented here were
conducted in July and August 2012 in the region Emilia
Romagna in Northern Italy. The measurement platform Zeppelin
NT allowed the observation of a comprehensive set of
chemical and physical parameter within the lower troposphere
between 75 − 900m above ground. During the measurement
flights, strong trace gas gradients were observed in the
early morning that could be explained by the layering within
the lanetary Boundary Layer. Typically, low trace gas
concentrations were found in the residual layer in high
altitudes whereas the highest OH reactivities up to 10
s$^{−1}$ and NO$_{x}$ mixing ratios up to 10 ppbv were
observed in the mixed layer which is strongly influenced by
ground emissions. The linear correlation between observed OH
and j(O$^{1}$D) with a slope of 4.4 × 10$^{11}$
cm$^{−3}$s is comparable to other field measurements in
continental regions. Additionally, the observed OH depends
nonlinearly on NO$_{x}$ resulting in enhanced mean OH
concentrations by a factor of 2 for NO$_{x}$ mixing ratios
between 1.5 and 2.0 ppbv. Observed mean HO$_{2}$
concentrations in air masses with [NO] < 250 pptv were up to
a factor of 5 higher than in air masses with [NO] > 1 ppbv.
For the first time, this HO$_{x}$ dependency on NO$_{x}$ was
observed locally when crossing vertical and horizontal
NO$_{x}$ gradients. Box model calculations based on the
Regional Atmospheric Chemistry Mechanism reproduce the
measured OH for [NO$_{x}$] < 3 ppbv. For higher NO$_{x}$
mixing ratios, the model overestimates OH for more than 50\%
of the data points. The model predicts HO$_{2}$ within the
uncertainty of the measurements and the model. The
prediction for OH could be improved by implementing a newly
proposed gas phase machanism forming HONO (Li et al., 2014).
The analysis of the HO$_{x}$ data does not hint at a
significant NO independent, non-classical OH-recycling
during the measurement flights performed in Italy.},
organization = {(Germany)},
cin = {IEK-8},
cid = {I:(DE-Juel1)IEK-8-20101013},
pnm = {233 - Trace gas and aerosol processes in the troposphere
(POF2-233)},
pid = {G:(DE-HGF)POF2-233},
typ = {PUB:(DE-HGF)3},
url = {https://juser.fz-juelich.de/record/155065},
}