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Using observed urban NOx sinks to constrain VOC reactivity and the ozone and radical budget in the Seoul Metropolitan Area.
- Source :
- EGUsphere; 4/2/2024, p1-55, 55p
- Publication Year :
- 2024
-
Abstract
- Ozone (O<subscript>3</subscript>) is an important secondary pollutant that impacts air quality and human health. Eastern Asia has high regional O<subscript>3</subscript> background due to the numerous sources and increasing and rapid industrial growth, which impacts the Seoul Metropolitan Area (SMA). However, SMA has also been experiencing increasing O<subscript>3</subscript> driven by decreasing NO<subscript>x</subscript> emissions, highlighting the role of local, in-situ O<subscript>3</subscript> production on SMA. Here, comprehensive gas-phase measurements collected on the NASA DC-8 during the NIER/NASA Korea United States-Air Quality (KORUS-AQ) study are used to constrain the instantaneous O<subscript>3</subscript> production rate over the SMA. The observed NO<subscript>x</subscript> oxidized products support the importance of non-measured peroxy nitrates (PNs) in the O<subscript>3</subscript> chemistry in SMA, as they accounted for ~49 % of the total PNs. Using the total measured PNs (ΣPNs) and alkyl and multifunctional nitrates (ΣANs), unmeasured volatile organic compound (VOC) reactivity (R(VOC)) is constrained and found to range from 1.4 – 2.1 s<superscript>-1</superscript>. Combining the observationally constrained R(VOC) with the other measurements on the DC-8, the instantaneous net O<subscript>3</subscript> production rate, which is as high as ~10 ppbv hr<superscript>-1</superscript>, along with the important sinks of O<subscript>3</subscript> and radical chemistry, are constrained. This analysis shows that ΣPNs play an important role in both the sinks of O<subscript>3</subscript> and radical chemistry. Since ΣPNs are assumed to be in steady-state, the results here highlight the role ΣPNs play in urban environments in reducing net O<subscript>3</subscript> production, but ΣPNs can potentially lead to increased net O<subscript>3</subscript> production downwind due to their short lifetime (~1 hr). The results provide guidance for future measurements to identify the missing R(VOCs) and ΣPNs production. [ABSTRACT FROM AUTHOR]
- Subjects :
- METROPOLITAN areas
RADICALS (Chemistry)
OZONE
VOLATILE organic compounds
AIR quality
Subjects
Details
- Language :
- English
- Database :
- Complementary Index
- Journal :
- EGUsphere
- Publication Type :
- Academic Journal
- Accession number :
- 176383815
- Full Text :
- https://doi.org/10.5194/egusphere-2024-596