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| Home > Publications database > Investigation of the photochemical activity in different MPC outflows during EMeRGe |
| Conference Presentation (Other) | FZJ-2021-00870 |
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2020
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Please use a persistent id in citations: doi:10.5194/egusphere-egu2020-18635
Abstract: <p>Since peroxy radicals are closely involved in a number of tropospheric chemical processes like O<sub>3</sub> budget, hydrocarbon oxidation and acid formation, the accurate measurement of these radicals can provide essential information to improve our understanding of processing and transformation of polluted outflows from megacities and Major Population Centres (MPCs).</p><p>Airborne measurements of the total sum of peroxy radicals, RO<sub>2</sub>*  = HO<sub>2</sub> + ∑ RO<sub>2</sub>, where R is an organic group, were conducted in Europe in summer 2017 and in East Asia in spring 2018 within the EMeRGe (Effect of Megacities on the Transport and Transformation of Pollutants on the Regional to Global Scales) project by using the PeRCEAS instrument (Peroxy Radical Chemical Enhancement and Absorption Spectrometer), on board of the HALO research aircraft (www.halo.dlr.de).</p><p>Over the course of both measurement campaigns different MPC outflows were investigated including among others, London, Rome, Manila and Taipei. Polluted air masses of different origin and composition were probed. Overall the peroxy radical mixing ratios were of the same order of magnitude in the air masses probed in Europe and in East Asia. The variations in the photochemical activity were studied by taking into account simultaneous observations of radical precursors and photolysis rates, while applying known oxidation mechanisms. Radical precursors, photolysis rates and aerosol load were generally higher in Asia, which might indicate higher radical loss reactions on the aerosol surface than in Europe. Moreover this study shows a clear deviation in the photostationary state for MPC outflows close to the emission sources. Based on this information, this presentation will focus on the actual understanding of the photochemical processing in the probed air masses.</p>
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