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Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
}
TY - JOUR
T1 - Low-NO atmospheric oxidation pathways in a polluted megacity
AU - Newland, M.J.
AU - Bryant, D.J.
AU - Dunmore, R.E.
AU - Bannan, T.J.
AU - Joe F. Acton, W.
AU - Langford, B.
AU - Hopkins, J.R.
AU - Squires, F.A.
AU - Dixon, W.
AU - Drysdale, W.S.
AU - Ivatt, P.D.
AU - Evans, M.J.
AU - Edwards, P.M.
AU - Whalley, L.K.
AU - Heard, D.E.
AU - Slater, E.J.
AU - Woodward-Massey, R.
AU - Ye, C.
AU - Mehra, A.
AU - Worrall, S.D.
AU - Bacak, A.
AU - Coe, H.
AU - Percival, C.J.
AU - Nicholas Hewitt, C.
AU - Lee, J.D.
AU - Cui, T.
AU - Surratt, J.D.
AU - Wang, X.
AU - Lewis, A.C.
AU - Rickard, A.R.
AU - Hamilton, J.F.
PY - 2021/2/8
Y1 - 2021/2/8
N2 - The impact of emissions of volatile organic compounds (VOCs) to the atmosphere on the production of secondary pollutants, such as ozone and secondary organic aerosol (SOA), is mediated by the concentration of nitric oxide (NO). Polluted urban atmospheres are typically considered to be "high-NO"environments, while remote regions such as rainforests, with minimal anthropogenic influences, are considered to be "low NO". However, our observations from central Beijing show that this simplistic separation of regimes is flawed. Despite being in one of the largest megacities in the world, we observe formation of gas- and aerosol-phase oxidation products usually associated with low-NO "rainforest-like"atmospheric oxidation pathways during the afternoon, caused by extreme suppression of NO concentrations at this time. Box model calculations suggest that during the morning high-NO chemistry predominates (95 %) but in the afternoon low-NO chemistry plays a greater role (30 %). Current emissions inventories are applied in the GEOS-Chem model which shows that such models, when run at the regional scale, fail to accurately predict such an extreme diurnal cycle in the NO concentration. With increasing global emphasis on reducing air pollution, it is crucial for the modelling tools used to develop urban air quality policy to be able to accurately represent such extreme diurnal variations in NO to accurately predict the formation of pollutants such as SOA and ozone.
AB - The impact of emissions of volatile organic compounds (VOCs) to the atmosphere on the production of secondary pollutants, such as ozone and secondary organic aerosol (SOA), is mediated by the concentration of nitric oxide (NO). Polluted urban atmospheres are typically considered to be "high-NO"environments, while remote regions such as rainforests, with minimal anthropogenic influences, are considered to be "low NO". However, our observations from central Beijing show that this simplistic separation of regimes is flawed. Despite being in one of the largest megacities in the world, we observe formation of gas- and aerosol-phase oxidation products usually associated with low-NO "rainforest-like"atmospheric oxidation pathways during the afternoon, caused by extreme suppression of NO concentrations at this time. Box model calculations suggest that during the morning high-NO chemistry predominates (95 %) but in the afternoon low-NO chemistry plays a greater role (30 %). Current emissions inventories are applied in the GEOS-Chem model which shows that such models, when run at the regional scale, fail to accurately predict such an extreme diurnal cycle in the NO concentration. With increasing global emphasis on reducing air pollution, it is crucial for the modelling tools used to develop urban air quality policy to be able to accurately represent such extreme diurnal variations in NO to accurately predict the formation of pollutants such as SOA and ozone.
U2 - 10.5194/acp-21-1613-2021
DO - 10.5194/acp-21-1613-2021
M3 - Journal article
VL - 21
SP - 1613
EP - 1625
JO - Atmospheric Chemistry and Physics
JF - Atmospheric Chemistry and Physics
SN - 1680-7316
IS - 3
ER -