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@ARTICLE{Rosanka:902279,
author = {Rosanka, Simon and Franco, Bruno and Clarisse, Lieven and
Coheur, Pierre-François and Wahner, Andreas and
Taraborrelli, Domenico},
title = {{O}rganic pollutants from tropical peatland fires: regional
influences and its impact on lower stratospheric ozone},
journal = {Atmospheric chemistry and physics / Discussions},
volume = {},
issn = {1680-7367},
address = {Katlenburg-Lindau},
publisher = {EGU},
reportid = {FZJ-2021-04142},
pages = {},
year = {2020},
abstract = {Abstract. The particularly strong dry season in Indonesia
in 2015, caused by an exceptional strong El Niño, led to
severe peatland fires resulting in high volatile organic
compound (VOC) biomass burning emissions. At the same time,
the developing Asian monsoon anticyclone (ASMA) and the
general upward transport in the intertropical convergence
zone (ITCZ) efficiently transported the resulting primary
and secondary pollutants to the upper troposphere/lower
stratosphere (UTLS). In this study, we assess the importance
of these VOC emissions for the composition of the lower
troposphere and the UTLS, and we investigate the effect of
in-cloud oxygenated VOC (OVOC) oxidation during such a
strong pollution event. This is achieved by performing
multiple chemistry simulations using the global atmospheric
model ECHAM/MESSy (EMAC). By comparing modelled columns of
the biomass burning marker hydrogen cyanide (HCN) to
spaceborne measurements from the Infrared Atmospheric
Sounding Interferometer (IASI), we find that EMAC properly
captures the exceptional strength of the Indonesian fires.
In the lower troposphere, the increase in VOC levels is
higher in Indonesia compared to other biomass burning
regions. This has a direct impact on the oxidation capacity,
resulting in the largest regional reduction in hydroxyl
radicals (OH) and nitrogen oxides (NOx). Even though an
increase in ozone (O3) is predicted close to the peatland
fires, particular high concentrations of phenols lead to an
O3 depletion in eastern Indonesia. By employing the detailed
in-cloud OVOC oxidation scheme Jülich Aqueous-phase
Mechanism of Organic Chemistry (JAMOC), we find that the
predicted changes are dampened and that by ignoring these
processes, global models tend to overestimate the impact of
such extreme pollution events. In the ASMA and the ITCZ, the
upward transport leads to elevated VOC concentrations in the
UTLS region, which results in a depletion of lower
stratospheric O3. We find that this is caused by a high
destruction of O3 by phenoxy radicals and by the increased
formation of NOx reservoir species, which dampen the
chemical production of O3. The Indonesian peatland fires
regularly occur during El Niño years and contribute to the
depletion of O3. In the time period from 2001 to 2016, we
find that the lower stratospheric O3 is reduced by about
0.38 DU and contributes to about 25 $\%$ to the lower
stratospheric O3 reduction observed by remote sensing. By
not considering these processes, global models might not be
able to reproduce this variability in lower stratospheric
O3.},
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},
doi = {10.5194/acp-2020-1130},
url = {https://juser.fz-juelich.de/record/902279},
}