To face up to the key issues confronting our society, of air-quality and climate change, we need to bring our chemical and physical knowledge to bear. This chemistry and physics control the composition of the air we breathe in the troposphere and the concentrations of key air-quality and climate gases. To be able to predict the composition of the atmosphere in many locations at once we need to understand all processes acting on chemical species from emissions, their transport, through to transformations in the gas- and aerosol- phase, to loss to rain and surfaces.
My interests are in trying to understand the composition of the troposphere using numerical models and comparing their predictions to observations. I use and develop the community-owned GEOS-Chem chemical transport model to predict and analyse composition at regional and global scales. By comparing with observations and developing models iteratively, we can seek answers to key questions for society and our planet such as air quality and climate change.
Alpine ice evidence of a three-fold increase in atmospheric iodine deposition since 1950 in Europe due to increasing oceanic emissions. M. Legrand, J. McConnell, S. Preunkert, M. Arienzo, N. Chellman, K. Gleason, T.Sherwen, M. Evans, L. Carpenter, Proceedings of the National Academy of Sciences of the U.S.A, 2018, DOI:10.1073/pnas.1809867115
Halogen chemistry reduces tropospheric O3 radiative forcing. T. Sherwen, M. J. Evans, L. J. Carpenter, J. A. Schmidt, and L. J. Mickley, Atmospheric Chemistry and Physics, 17, 1557-1569, 2017, DOI: 10.5194/acp-17-1557-2017.
Global impacts of tropospheric halogens (Cl, Br, I) on oxidants and composition in GEOS-Chem. Sherwen, T, Schmidt, JA, Evans, MJ, Carpenter, LJ, Großmann, K, Eastham, SD, Jacob, DJ, Dix, B, Koenig, TK, Sinreich, R, Ortega, I, Volkamer, R, Saiz-Lopez, A, Prados-Roman, C, Mahajan, AS & Ordóñez, C, Atmospheric Chemistry and Physics, 16, 12239-12271, 2016, DOI: 10.5194/acp-16-12239-2016.
Effects of halogens on European air-quality. T. Sherwen, M. J. Evans, R. Sommariva, L. D. J. Hollis, S. M. Ball, P. S. Monks, C. Reed, L. J. Carpenter, J. D. Lee, G. Forster, B. Bandy, C. E. Reeves and W. J. Bloss, Faraday Discussions, 200, 75-100, 2017, DOI: 10.1039/C7FD00026J.
Modelling the observed tropospheric BrO background: Importance of multiphase chemistry and implications for ozone, OH, and mercury. J. A. Schmidt, D. J. Jacob, H. M. Horowitz, L. Hu, T. Sherwen, M. J. Evans, Q. Liang, R. M. Suleiman, D. E. Oram, M. Le Breton, C. J. Percival, S. Wang, B. Dix, R. Volkamer, Journal of Geophysical Research: Atmospheres, 121, 11, 819–11, 835, 2016, DOI: 10.1002/2015JD024229.
Department of Chemistry University of York,
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