Ozone seasonal evolution and photochemical production regime in the polluted troposphere in eastern China derived from high-resolution Fourier transform spectrometry (FTS) observations
<p>The seasonal evolution of O<sub>3</sub> and its photochemical production regime in a polluted region of eastern China between 2014 and 2017 has been investigated using observations. We used tropospheric ozone (O<sub>3</sub>), carbon monoxide (CO), and formaldehyde...
| Main Authors: | , , , , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2018-10-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://www.atmos-chem-phys.net/18/14569/2018/acp-18-14569-2018.pdf |
| Summary: | <p>The seasonal evolution of O<sub>3</sub> and its photochemical
production regime in a polluted region of eastern China between 2014 and 2017
has been investigated using observations. We used tropospheric ozone
(O<sub>3</sub>), carbon monoxide (CO), and formaldehyde (HCHO, a marker of VOCs
(volatile organic compounds)) partial columns derived from high-resolution
Fourier transform spectrometry (FTS); tropospheric nitrogen dioxide
(NO<sub>2</sub>, a marker of NO<sub><i>x</i></sub> (nitrogen oxides)) partial
column deduced from the Ozone Monitoring Instrument (OMI); surface meteorological
data; and a back trajectory cluster analysis technique. A broad O<sub>3</sub>
maximum during both spring and summer (MAM/JJA) is observed; the day-to-day
variations in MAM/JJA are generally larger than those in autumn and winter
(SON/DJF). Tropospheric O<sub>3</sub> columns in June are 1.55×10<sup>18</sup> molecules cm<sup>−2</sup> (56 DU (Dobson units)), and in December they are
1.05×10<sup>18</sup> molecules cm<sup>−2</sup> (39 DU). Tropospheric O<sub>3</sub>
columns in June were ∼ 50 % higher than those in December. Compared
with the SON/DJF season, the observed tropospheric O<sub>3</sub> levels in MAM/JJA
are more influenced by the transport of air masses from densely populated and
industrialized areas, and the high O<sub>3</sub> level and variability in
MAM/JJA is determined by the photochemical O<sub>3</sub> production. The
tropospheric-column HCHO∕NO<sub>2</sub> ratio is used as a proxy to
investigate the photochemical O<sub>3</sub> production rate (PO<sub>3</sub>).
The results show that the PO<sub>3</sub> is mainly nitrogen oxide (NO<sub><i>x</i></sub>) limited in MAM/JJA, while it is mainly VOC or mixed VOC–NO<sub><i>x</i></sub> limited in SON/DJF. Statistics show that
NO<sub><i>x</i></sub>-limited, mixed VOC–NO<sub><i>x</i></sub>-limited, and VOC-limited PO<sub>3</sub> accounts for 60.1 %, 28.7 %, and 11 % of days,
respectively. Considering most of PO<sub>3</sub> is NO<sub><i>x</i></sub>
limited or mixed VOC–NO<sub><i>x</i></sub> limited, reductions in
NO<sub><i>x</i></sub> would reduce O<sub>3</sub> pollution in eastern China.</p> |
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| ISSN: | 1680-7316 1680-7324 |