Dr Tomás Sherwen

NCAS Research Scientist

Phone: 01904 324758
Email: tomas.sherwen@york.ac.uk

Research Interests

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 and aerosols. 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 understanding the composition of the troposphere using numerical modelling techniques and working with observations to iteratively improve models and predictive ability. I use and develop the open-source & community-owned GEOS-Chem chemical transport model to predict and analyse composition at regional and global scales, as well as using other techniques (e.g. machine learning). By comparing observations and developing models iteratively, we can seek answers to key questions for society and the environment.

Selected Publications

Isotopic evidence for acidity-driven enhancement of sulfate formation after SO2 emission control, Hattori, S., Iizuka, Y., Alexander, B., Ishino, S., Fujita, K., Zhai, S., Sherwen, T., Oshima, N., Uemura, R., Yamada, A. and Suzuki, N, Science Advances, 7(19), p.eabd4610. DOI:10.1126/sciadv.abd4610
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
Effects of sea salt aerosol emissions for Marine Cloud Brightening on atmospheric chemistry: Implications for radiative forcing. Horowitz, H.M., Holmes, C., Wright, A., Sherwen, T., Wang, X., Evans, M., Huang, J., Jaeglé, L., Chen, Q., Zhai, S. and Alexander, B., Geophysical research letters, 47(4), p.e2019GL085838. 2020, DOI:10.1029/2019GL085838
A machine-learning-based global sea-surface iodide distribution. Sherwen, T., Chance, R.J., Tinel, L., Ellis, D., Evans, M.J. and Carpenter, L.J., Earth System Science Data, 11(3), 1239-1262, 2019, DOI:10.5194/essd-11-1239-2019
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.