Supervisors: Louise Sime (British Antarctic Survey), Eric Wolff (Earth Sciences) and Dan Lunt (University of Bristol)
Importance of the area of research:
Antarctic ice cores represent unique archives of dust. The dust is transported over long distances, typically from desert regions, over the Southern Ocean, before being buried in the ice sheet. In the ice it is stable and perfectly preserved. Measurements from ice cores thus allow changes in dust to be deduced over very long time periods (Wolff et al 2006). These measurements tell a remarkable story: dust was up to 25 times more common during the depths of the last ice age compared to now.
The amount of dust in the atmosphere around Antarctica plays a huge role in the climate system. It changes the radiative balance of the atmosphere and may impact climate by modifying cloud properties, for example by providing cloud condensation nuclei. The supply of dust is also the major source of iron in the Southern Ocean, which is an essential micronutrient for phytoplankton growth. Dust is therefore also thought to be critical to the atmosphere-ocean carbon budget and resultant pCO2.
You will investigate and attempt to explain why Antarctica was so much dustier during the Last Ice Age. A variety of hypothesis have been proposed to explain the dust changes. You will test the hypotheses, which are as follows. H1: North-south shifts in the belt of Southern Ocean winds caused the dust to increase. H2: A drier atmosphere permitted more dust to reach Antarctic. H3: Vegetation and sea level change cause dust sources to expand.
What the student will do:
You will use an approach which combines state-of-the art climate modelling and data from a series of Antarctic ice cores. Your models will be the MetOffice Hadley Centre HadGEM3 model, and the atmospheric aerosol and chemistry model TOMCAT. By using these models to run a series of sensitivity experiments, you will be able to test which of the dust-hypotheses can best explain the Antarctic ice core measurements.
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.
Sime, L. C. and Wolff, E. et al. (2013) Southern Hemisphere westerly wind changes during the Last Glacial Maximum: model-data comparison. Quaternary Science Reviews, 64. 104-120. 10.1016/j.quascirev.2012.12.008
Sudarchikova, N. et al., 2015, Modelling of mineral dust for interglacial and glacial climate conditions with a focus on Antarctica, Clim. Past, 11, 765-779, 2015
Wolff, E.W. et al. 2006 Southern Ocean sea-ice extent, productivity and iron flux over the past eight glacial cycles, Nature, 440, 491–496, doi: 10.1038/nature04614
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