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@ARTICLE{Ma:866675,
author = {Ma, Xuefei and Tan, Zhaofeng and Lu, Keding and Yang,
Xinping and Liu, Yuhan and Li, Shule and Li, Xin and Chen,
Shiyi and Novelli, Anna and Cho, Changmin and Zeng, Limin
and Wahner, Andreas and Zhang, Yuanhang},
title = {{W}inter photochemistry in {B}eijing: {O}bservation and
model simulation of {OH} and {HO}2 radicals at an urban
site},
journal = {The science of the total environment},
volume = {685},
issn = {0048-9697},
address = {Amsterdam [u.a.]},
publisher = {Elsevier Science},
reportid = {FZJ-2019-05753},
pages = {85 - 95},
year = {2019},
abstract = {A field campaign was conducted from November to December
2017 at the campus of Peking University (PKU) to investigate
the formation mechanism of the winter air pollution in
Beijing with the measurement of hydroxyl and hydroperoxyl
radical (OH and HO2) with the support from comprehensive
observation of trace gases compounds. The extent of air
pollution depends on meteorological conditions. The daily
maximum OH radical concentrations are on average
2.0 × 106 cm−3 and 1.5 × 106 cm−3 during
the clean and polluted episodes, respectively. The daily
maximum HO2 radical concentrations are on average
0.4 × 108 cm−3 and 0.3 × 108 cm−3 during
the clean and polluted episodes, respectively (diurnal
averaged for one hour bin). A box model based on RACM2-LIM1
mechanism can reproduce the OH concentrations but
underestimate the HO2 concentrations by $50\%$ during the
clean episode. The OH and HO2 concentrations are
underestimated by $50\%$ and 12 folds during the polluted
episode, respectively. Strong dependence on nitric oxide
(NO) concentration is found for both observed and modeled
HO2 concentrations, with the modeled HO2 decreasing more
rapidly than observed HO2, leading to severe HO2
underestimation at higher NO concentrations. The OH
reactivity is calculated from measured and modeled species
and inorganic compounds (carbon monoxide (CO), NO, and
nitrogen dioxide (NO2)) make up $69\%–76\%$ of the
calculated OH reactivity. The photochemical oxidation rate
denoted by the OH loss rate increases by 3 times from the
clean to polluted episodes, indicating the strong oxidation
capacity in polluted conditions. The comparison between
measurements at PKU site and a suburban site from one
previous study shows that chemical conditions are similar in
both urban and suburban areas. Hence, the strong oxidation
capacity and its potential contribution to the pollution
bursts are relatively homogeneous over the whole Beijing
city and its surrounding areas.},
cin = {IEK-8},
ddc = {610},
cid = {I:(DE-Juel1)IEK-8-20101013},
pnm = {243 - Tropospheric trace substances and their
transformation processes (POF3-243)},
pid = {G:(DE-HGF)POF3-243},
typ = {PUB:(DE-HGF)16},
pubmed = {pmid:31174126},
UT = {WOS:000477951900009},
doi = {10.1016/j.scitotenv.2019.05.329},
url = {https://juser.fz-juelich.de/record/866675},
}