Lead supervisor: Alexander Archibald, Chemistry
Co-supervisor: Tom Bell, Plymouth Marine Laboratory; Luke Abraham, Chemistry
Brief summary:
The marine sulfur cycle is an exemplar of a climatically important biogeochemical cycle within the Earth system. But it is subject to significant uncertainties, uncertainties that can be constrained and reduced through this projects combination of numerical modelling and field work.
Importance of the area of research concerned:
Marine sulfate aerosol produced from biogenic dimethyl sulfide (DMS) is the main component of natural aerosol over many oceanic regions and sets a baseline aerosol concentration against which the magnitude of anthropogenic aerosol radiative forcing is determined. However, recent discoveries of new sulfur molecules formed from DMS force us to radically re-examine the role of marine sulfur in the climate system. The understanding embedded in current climate models is now significantly challenged by new aerosol formation pathways and by observations of marine emissions of other biogenic sulfur species that were previously dismissed as unimportant: What do these molecules do? How do the processes they participate in affect the natural sulfur cycle? How do these discoveries alter the impact of DMS emissions on climate and anthropogenically driven climate change? The recently discovered species and chemical pathways are not included in any Earth system models that inform global climate change policies through the IPCC, even though aerosols from natural sources are a key driver of uncertainty in radiative forcing.
Project summary :
This project will fill the holes in our knowledge of the marine atmospheric sulfur cycle through a combination of intensive aircraft and ship observations as well as multi-scale model experiments. Advancements in models, further informed by new laboratory data, will allow us to better understand contemporary and historical sulfur and climate observations. This will deliver a substantial revision to our understanding of the fate and impact of natural sulfur emissions. The results will be used to rectify errors in the representation of sulfur processes in Earth system models, constrain the role of marine sulfur in the Earth System, and improve confidence in simulations that project future change.
What will the student do?:
You will be trained in the development and execution of numerical model simulations, the interpretation of large data sets using Data Science techniques (including machine learning), and how to collect, analyse and interpret field data. There will be a unique opportunity for you to take a leadership role in the aircraft or ship based field studies by leading some experiments (under the mentorship of an experienced team). You will use this wealth of data to constrain and reduce uncertainty and undoubtedly uncover new discoveries in this fascinating area of Earth system science.
References - references should provide further reading about the project:
Cala, B. A., Archer-Nicholls, S., Weber, J., Abraham, N. L., Griffiths, P. T., Jacob, L., Shin, Y. M., Revell, L. E., Woodhouse, M., and Archibald, A. T.: Development, intercomparison and evaluation of an improved mechanism for the oxidation of dimethyl sulfide in the UKCA model, Atmos. Chem. Phys. Discuss. [preprint], https://doi.org/10.5194/acp-2023-42, in review, 2023.
Hopkins, F.E., Archer, S.D., Bell, T.G., Suntharalingam, P. and Todd, J.D., 2023. The biogeochemistry of marine dimethylsulfide. Nature Reviews Earth & Environment, 4(6), pp.361-376. https://www.nature.com/articles/s43017-023-00428-7
Fung, K. M., Heald, C. L., Kroll, J. H., Wang, S., Jo, D. S., Gettelman, A., Lu, Z., Liu, X., Zaveri, R. A., Apel, E. C., Blake, D. R., Jimenez, J.-L., Campuzano-Jost, P., Veres, P. R., Bates, T. S., Shilling, J. E., and Zawadowicz, M.: Exploring dimethyl sulfide (DMS) oxidation and implications for global aerosol radiative forcing, Atmos. Chem. Phys., 22, 1549–1573, https://doi.org/10.5194/acp-22-1549-2022, 2022.
Applying
You can find out about applying for this project on the Department of Chemistry page.