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C303: Halogens in the Antarctic snow/ice/atmosphere system (Lead Supervisor: Anna Jones, British Antarctic Survey)

Supervisors: Anna Jones (British Antarctic Survey) and Eric Wolff (Earth Sciences)

Importance of the area of research:

Halogens, especially bromine and iodine compounds, have multi-faceted importance for the polar regions. They can be released from sea ice into the atmosphere and affect both the chemistry of the air, and production of aerosols, which ultimately influence the radiation balance in the region. Further, a signal of halogen concentrations is tied up in the snowpack, and is ultimately buried in deep snow layers. This signal can be retrieved when ice cores are drilled, and may include information on the extent of sea ice at the time that the snow fell. Halogens in ice cores could thus be a powerful proxy of how sea ice has changed over thousands of years – important for testing sea ice models, and for putting recent sea ice changes into context. Details of processes involved when halogens are buried in snow are far from known, so although this sea-ice proxy has great potential, it critically needs development and testing.

Project summary:

The goal of this project is to extend our understanding of halogens at the boundary between the atmosphere and cryosphere. You will use a combination of approaches, including laboratory analysis of existing samples, data analysis, simple computer modelling, as well as laboratory process studies, to pin down how halogens interact with snow/ice, how a signal builds up in ice cores, and what environmental variables control it. Your results will be interpreted in conjunction with existing knowledge of air/snow exchange mechanisms, and existing sea ice proxies, to test ideas on the role of halogens in the Antarctic atmosphere, and their use as sea ice proxies

What the student will do:

The student will carry out laboratory analysis of a wonderful suite of existing snow/ice core samples to derive concentrations of halogens and how they vary with space and time. They will support their data interpretation with meteorological observations and simple modelling, to figure out how an ice core halogen signal is built up and what it actually means. The student will investigate the processes driving exchange of halogens between air and snow by conducting laboratory experiments, employing sophisticated instrumentation and controlling parameters such as light levels/wavelengths, and temperature. Finally, they will interpret existing measurements of halogens in the Antarctic atmosphere using supporting observations and simple models, and likely in comparison with other Antarctic stations. Each facet of this project will answer open questions in polar science and the results together will build to provide a significant advance in knowledge. The student’s interests will be fully taken into account when determining project direction.

Please contact the lead supervisor directly for further information relating to what the successful applicant will be expected to do, training to be provided, and any specific educational background requirements.

References:

J. P. D. Abbatt, J. L. Thomas, K. Abrahamsson, C. Boxe, A. Granfors, A. E. Jones, M. D. King, A. Saiz-Lopez, P. B. Shepson, J. Sodeau, D. W. Toohey, C. Toubin, R. von Glasow, S. N. Wren, and X. Yang, Halogen activation via interactions with environmental ice and snow in the polar lower troposphere and other regions, Atmos. Chem. Phys., 12, 6237-6271, 2012.

Friess, U., Deutschmann, T., Gilfedder, B.S., Weller, R., and Platt, U., Iodine monoxide in the Antarctic snowpack, Atmos. Chem. Phys., vol 10, 2439-2456, 2010.

Spolaor, A., P. Vallelonga, J. M. C. Plane, N. Kehrwald, J. Gabrieli, C. Varin, C. Turetta, G. Cozzi,

R. Kumar, C. Boutron, and C. Barbante, 2013. Atmos. Chem. Phys., vol. 13(13), pp. 6623-6635, doi:10.5194/acp-13-6623-2013.

Follow this link to find out about applying for this project.

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