% IMPORTANT: The following is UTF-8 encoded. This means that in the presence
% of non-ASCII characters, it will not work with BibTeX 0.99 or older.
% Instead, you should use an up-to-date BibTeX implementation like “bibtex8” or
% “biber”.
@ARTICLE{Tan:866650,
author = {Tan, Zhaofeng and Lu, Keding and Hofzumahaus, Andreas and
Fuchs, Hendrik and Bohn, Birger and Holland, Frank and Liu,
Yuhan and Rohrer, Franz and Shao, Min and Sun, Kang and Wu,
Yusheng and Zeng, Limin and Zhang, Yinsong and Zou, Qi and
Kiendler-Scharr, Astrid and Wahner, Andreas and Zhang,
Yuanhang},
title = {{E}xperimental budgets of {OH}, {HO} 2 , and {RO} 2
radicals and implications for ozone formation in the {P}earl
{R}iver {D}elta in {C}hina 2014},
journal = {Atmospheric chemistry and physics},
volume = {19},
number = {10},
issn = {1680-7324},
address = {Katlenburg-Lindau},
publisher = {EGU},
reportid = {FZJ-2019-05729},
pages = {7129 - 7150},
year = {2019},
abstract = {Hydroxyl (OH) and peroxy radicals (HO2 and RO2) were
measured in the Pearl River Delta, which is one of the most
polluted areas in China, in autumn 2014. The radical
observations were complemented by measurements of OH
reactivity (inverse OH lifetime) and a comprehensive set of
trace gases including carbon monoxide (CO), nitrogen oxides
(NOx=NO, NO2) and volatile organic compounds (VOCs). OH
reactivity was in the range from 15 to 80 s−1, of which
about $50 \%$ was unexplained by the measured OH
reactants. In the 3 weeks of the campaign, maximum median
radical concentrations were 4.5×106 cm−3 for OH at noon
and 3×108 and 2.0×108 cm−3 for HO2 and RO2,
respectively, in the early afternoon. The completeness of
the daytime radical measurements made it possible to carry
out experimental budget analyses for all radicals (OH, HO2,
and RO2) and their sum (ROx). The maximum loss rates for OH,
HO2, and RO2 reached values between 10 and 15 ppbv h−1
during the daytime. The largest fraction of this can be
attributed to radical interconversion reactions while the
real loss rate of ROx remained below 3 ppbv h−1.
Within experimental uncertainties, the destruction rates of
HO2 and the sum of OH, HO2, and RO2 are balanced by their
respective production rates. In case of RO2, the budget
could be closed by attributing the missing OH reactivity to
unmeasured VOCs. Thus, the presumption of the existence of
unmeasured VOCs is supported by RO2 measurements. Although
the closure of the RO2 budget is greatly improved by the
additional unmeasured VOCs, a significant imbalance in the
afternoon remains, indicating a missing RO2 sink. In case of
OH, the destruction in the morning is compensated by the
quantified OH sources from photolysis (HONO and O3),
ozonolysis of alkenes, and OH recycling (HO2+NO). In the
afternoon, however, the OH budget indicates a missing OH
source of 4 to 6 ppbv h−1. The diurnal variation of
the missing OH source shows a similar pattern to that of the
missing RO2 sink so that both largely compensate each other
in the ROx budget. These observations suggest the existence
of a chemical mechanism that converts RO2 to OH without the
involvement of NO, increasing the RO2 loss rate during the
daytime from 5.3 to 7.4 ppbv h−1 on average. The
photochemical net ozone production rate calculated from the
reaction of HO2 and RO2 with NO yields a daily integrated
amount of 102 ppbv ozone, with daily integrated ROx
primary sources being 22 ppbv in this campaign. The
produced ozone can be attributed to the oxidation of
measured $(18 \%)$ and unmeasured $(60 \%)$
hydrocarbons, formaldehyde $(14 \%),$ and CO $(8 \%).$
An even larger integrated net ozone production of 140 ppbv
would be calculated from the oxidation rate of VOCs with OH
if HO2 and all RO2 radicals react with NO. However, the
unknown RO2 loss (evident in the RO2 budget) causes
30 ppbv less ozone production than would be expected from
the VOC oxidation rate.},
cin = {IEK-8},
ddc = {550},
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},
UT = {WOS:000469430600001},
doi = {10.5194/acp-19-7129-2019},
url = {https://juser.fz-juelich.de/record/866650},
}