A146-0010
Rainforest-like Atmospheric Chemistry in a Polluted Megacity
Monday, 14 December 2020
Poster
Mike Newland1, Daniel Bryant2, Rachel Dunmore3, Tom Bannan4, W. Joe F. Acton5, Ben Langford6, James R Hopkins3, Freya Anne Squires3, William Dixon2, William S Drysdale3, Peter Ivatt7, Mathew J Evans7, Pete Edwards7, Lisa Whalley8, Dwayne E Heard8, Eloise Slater9,10, Robert Woodward-Massey11, Chunxiang Ye12, Archit Mehra4, Stephen D Worrall13, Asan Bacak14, Hugh Coe15, Carl Percival16, C Nick Hewitt5, James D Lee3, Tianqu Cui17, Jason D Surratt18, Xinming Wang19, Alistair C Lewis20, Andrew R Rickard21 and Jacqueline Hamilton3, (1)University of York, York, YO10, United Kingdom, (2)University of York, York, United Kingdom, (3)University of York, Wolfson Atmospheric Chemistry Laboratories, Department of Chemistry, York, United Kingdom, (4)University of Manchester, Manchester, United Kingdom, (5)University of Lancaster, Lancaster Environment Centre, Lancaster, United Kingdom, (6)Centre for Ecology and Hydrology, Edinburgh, United Kingdom, (7)Wolfson Atmospheric Chemistry Laboratories, Department of Chemistry, University of York, York, United Kingdom, (8)University of Leeds, School of Chemistry, Leeds, LS2, United Kingdom, (9)University of Leeds, School of Chemsitry, Leeds, AL, United Kingdom, (10)University of Leeds, School of Chemistry, Leeds, United Kingdom, (11)Peking University, Beijing, China, (12)Wadsworth Center, Albany, United States, (13)Aston University, Chemical Engineering and Applied Chemistry, Birmingham, United Kingdom, (14)University of Manchester, Centre for Atmospheric Science, School of Earth, Atmospheric and Environmental Sciences, Manchester, United Kingdom, (15)Department of Earth and Environmental Sciences, University of Manchester, Manchester, United Kingdom, (16)NASA Jet Propulsion Laboratory, Pasadena, CA, United States, (17)University of North Carolina at Chapel Hill, Chapel Hill, NC, United States, (18)UNC-Environment Sci & Eng, Chapel Hill, NC, United States, (19)Chinese Academy Of Sciences, Guangzhou, China, (20)University of York, Wolfson Atmospheric Chemistry Laboratories, York, United Kingdom, (21)National Centre for Atmospheric Science, York, United Kingdom
Abstract:
The impact of volatile organic compound (VOC) emissions 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 significant formation of gas and aerosol phase oxidation products associated with the low-NO ‘rainforest-like’ regime during the afternoon, caused by extreme suppression of NO concentrations in the afternoon. 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.
