Der Einfluss subglazialer Hydrologie und der Eisschild-Wasser-Wechselwirkung auf die Eisdynamik der Antarktis:Subglaziale Seen und Drainagesysteme
Zusammenfassung der Projektergebnisse
During the DFG project a coupled ice flow-lake circulation model has been developed, based on well established components. This model was used to perform investigations on the interaction between subglacial water systems and the overlying ice sheet. Especially the influence of lakes on ice dynamics has been one focus of this work. Subglacial water acts as a lubricator for the ice flow, enhancing ice transport far beyond the limits of the actual water occurence. On the other hand melting or freezing conditions in subglacial lakes also impact the thermal structure and thus the deformation regime of the overlying ice sheet. In dependence of the ice sheet thickness the dynamic conditions of a subglacial lake can be in different states. Subglacial Lake Ellsworth provides a situation where the line of maximum density LoMD and thus the change between the two dynamic states cross through the lake itself. In dependence of variations in ice thickness the lake will undergo a strong change. This is especially important as British scientists plan to penetrate into this lake in near future. A joint investigation was used to identify the specific conditions for planned drill locations. Subglacial lakes are only the accumulators of migrating subglacial water, produced underneath large parts of the ice sheet. The interconnection between the generation of melt water, the routing of this water and the water accumulation is one of the important questions for future ice sheet investigations. Fundamental routing mechanisms and their influence on ice dynamics have been investigated in a detailed case study. Within this study new approaches for routing water in subglacial systems have been developed and applied. The aggregation of water in larger drainage systems clearly influences the overlying ice dynamics. Applications of the developed model system for different set-ups are on the way.
Projektbezogene Publikationen (Auswahl)
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Modelling flow and accreted ice in subglacial Lake Concordia, Antarctica, Earth Planet. Sci. Lett., 286, 278-284, 2009
Thoma, M., Filina, I., Grosfeld, K., and Mayer, C.
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Modelling ice-lake interaction processes and their feedbacks on the flow of the Antarctic Ice Sheet, International Glaciological Society: International Symposium on Glaciology in the International Polar Year 27.-31.7.2009, Newcaste, UK
Thoma, M., Grosfeld, K., Mayer, C., and Pattyn, F.
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Subglacial Lakes in Antarctica: Numerical modelling. Svartisen Subglacial laboratory - Subglacial workshop, 25.-26.3.2009, Norway
Thoma, M., Grosfeld, K., Mayer, C., and Pattyn, F.
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A comment on the equation of state and the freezing point equation with respect to subglacial lake modelling, Earth Planet. Sci. Lett., 294, 80-84, 2010
Thoma, M., Grosfeld, K., Smith, A. M., and Mayer, C.
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Antarctic subglacial lakes: I: Temperature Profiles (Subglacial Lake Ellsworth) II: Impact on Ice Flow (Subglacial Lake Vostok), 24th International Forum for Research into Ice Shelf Processes (FRISP). 21-24 June 2010, Bad Bederkesa, Germany
Thoma, M., Grosfeld, K., Mayer, C., Smith, A. M., Woodward, J., Ross, N., and Pattyn, F.
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Interaction between ice sheet dynamics and subglacial lake circulation: a coupled modelling approach, The Cryosphere, 4, 1-12, 2010
Thoma, M., Grosfeld, K., Mayer, C., and Pattyn, F.
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Location for direct access to subglacial Lake Ellsworth: An assessment of geophysical data and modeling, Geophys. Res. Lett., 37, 2010
Woodward, J., Smith, A. M., Ross, N., Thoma, M., Corr, H. F. J., King, E. C., King, M. A., Grosfeld, K., Tranter, M., and Siegert, M. J.
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Subglacial Lake Regimes, the hydrological conditions at the bottom of the Antarctic Ice Sheet, 24. Internationale Polartagung, Obergurgl, 2010
Mayer, C., Thoma, M., Siegert, M. J., and Wright, A.
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Subglacial Lake Vostok: Impact of the basal mass balance of subglacial lakes on the ice sheet, in: 24. Interationale Polartagung, Programm und Zusammenfassung der Tagungsbeiträge, edited by Kuhn, M., vol. 2010/5, p. 56, GeoUnion, Alfred-Wegner-Stiftung, 2010
Thoma, M., Grosfeld, K., Mayer, C., and Pattyn, F.
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Tipping temperatures within Subglacial Lake Ellsworth, West Antarctica, in: 24. Interationale Polartagung, Programm und Zusammenfassung der Tagungsbeiträge, edited by Kuhn, M., vol. 2010/5, pp. 92-93, GeoUnion, Alfred-Wegner-Stiftung, 2010
Thoma, M., Grosfeld, K., Mayer, C., Smith, A. M., Woodward, J., Ross, N., and Siegert, M.
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Ice-Shelf Ocean Interaction, Workshop on Numerical Methods for Scale Interactions, Hamburg, 2011
Thoma, M., Grosfeld, K., Hellmer, H., and Timmermann, R.
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Lake Vostok, in: Encyclopedia of Snow, Ice and Glaciers, edited by Singh, V. P., Singh, P., and Haritashya, U. K., Springer, Dordrecht, The Netherlands, ISBN: 978-90-481-2641-5, 2011
Thoma, M.
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Subglacial Lakes in Antarctica: Origin, Fate, and Relevance, 75th Annual Meeting of the DPG and combined DPG Spring Meeting, 13-18 March 2011, Dresden, Germany
Thoma, M., Goeller, S., Grosfeld, K., and Mayer, C.
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The "tipping" temperature within Subglacial Lake Ellsworth, West Antarctica and its implications for lake access. The Cryosphere, 5, 561-567, 2011
Thoma, M., Grosfeld, K., Mayer, C., Smith, A. M., Woodward, J., and Ross, N.
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A multi-physics 3D ice-sheet model for comprehensive applications: Model-description & examples, REKLIM Workshop, 19.-21. March 2012, Lüneburg
Thoma, M., Grosfeld, K., Determann, J., Barbi, D., and Goeller, S.
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Ice streams and subglacial lakes - the crucial impact of basal hydrology on ice sheet modeling, 72. Jahrestagung der Deutschen Geophysikalischen Gesellschaft, 5.-8. März, 2012, Universität Hamburg
Goeller, S., Thoma, M., Grosfeld, K., and Miller, H.
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Ice streams and subglacial lakes: the crucial impact of basal hydrology on ice sheet modeling, REKLIM Workshop, 19.-21. March 2012, Lüneburg
Goeller, S., Thoma, M., Grosfeld, K., and Miller, H.
