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@ARTICLE{Tadic:902276,
author = {Tadic, Ivan and Nussbaumer, Clara M. and Bohn, Birger and
Harder, Hartwig and Marno, Daniel and Martinez, Monica and
Obersteiner, Florian and Parchatka, Uwe and Pozzer, Andrea
and Rohloff, Roland and Zöger, Martin and Lelieveld, Jos
and Fischer, Horst},
title = {{C}entral role of nitric oxide in ozone production in the
upper tropical troposphere over the {A}tlantic {O}cean and
western {A}frica},
journal = {Atmospheric chemistry and physics},
volume = {21},
number = {10},
issn = {1680-7324},
address = {Katlenburg-Lindau},
publisher = {EGU},
reportid = {FZJ-2021-04139},
pages = {8195 - 8211},
year = {2021},
abstract = {Mechanisms of tropospheric ozone (O3) formation are
generally well understood. However, studies reporting on net
ozone production rates (NOPRs) directly derived from in situ
observations are challenging and are sparse in number. To
analyze the role of nitric oxide (NO) in net ozone
production in the upper tropical troposphere above the
Atlantic Ocean and western Africa, we present in situ trace
gas observations obtained during the CAFE-Africa (Chemistry
of the Atmosphere: Field Experiment in Africa) campaign in
August and September 2018. The vertical profile of in situ
measured NO along the flight tracks reveals lowest NO mixing
ratios of less than 20 pptv between 2 and 8 km altitude
and highest mixing ratios of 0.15–0.2 ppbv above 12 km
altitude. Spatial distribution of tropospheric NO above
12 km altitude shows that the sporadically enhanced local
mixing ratios (>0.4 ppbv) occur over western Africa, which
we attribute to episodic lightning events. Measured O3 shows
little variability in mixing ratios at 60–70 ppbv, with
slightly decreasing and increasing tendencies towards the
boundary layer and stratosphere, respectively. Concurrent
measurements of CO, CH4, OH, HO2 and H2O enable calculations
of NOPRs along the flight tracks and reveal net ozone
destruction at −0.6 to −0.2 ppbv h−1 below 6 km
altitude and balance of production and destruction around
7–8 km altitude. We report vertical average NOPRs of
0.2–0.4 ppbv h−1 above 12 km altitude with NOPRs
occasionally larger than 0.5 ppbv h−1 over western
Africa coincident with enhanced NO. We compare the
observational results to simulated data retrieved from the
general circulation model ECHAM/MESSy Atmospheric Chemistry
(EMAC). Although the comparison of mean vertical profiles of
NO and O3 indicates good agreement, local deviations between
measured and modeled NO are substantial. The vertical
tendencies in NOPRs calculated from simulated data largely
reproduce those from in situ experimental data. However, the
simulation results do not agree well with NOPRs over western
Africa. Both measurements and simulations indicate that
ozone formation in the upper tropical troposphere is NOx
limited.},
cin = {IEK-8},
ddc = {550},
cid = {I:(DE-Juel1)IEK-8-20101013},
pnm = {2111 - Air Quality (POF4-211)},
pid = {G:(DE-HGF)POF4-2111},
typ = {PUB:(DE-HGF)16},
UT = {WOS:000657177200004},
doi = {10.5194/acp-21-8195-2021},
url = {https://juser.fz-juelich.de/record/902276},
}