Antarctic subglacial hydrology - interactions of subglacial lakes, basal water flow and ice dynamics
The Antarctic Ice Sheet influences the global temperature and sea level by complex interactions with the atmosphere and the ocean and is thus an important factor in the Earth's climate system. Recent climate assessments reveal a steady increase of global temperatures and an on-going shrinking o...
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| Other Authors: | , |
| Format: | Doctoral or Postdoctoral Thesis |
| Language: | English |
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Universität Bremen
2014
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| Online Access: | https://media.suub.uni-bremen.de/handle/elib/684 https://nbn-resolving.org/urn:nbn:de:gbv:46-00103852-13 |
| Summary: | The Antarctic Ice Sheet influences the global temperature and sea level by complex interactions with the atmosphere and the ocean and is thus an important factor in the Earth's climate system. Recent climate assessments reveal a steady increase of global temperatures and an on-going shrinking of glaciers and ice sheets. Because the total Antarctic ice volume has the potential to raise the global sea level by about 58 meters, it is of particular interest to understand the ice dynamics regarding the mass export and thus the contribution to sea level rise. Observations of the last decades reveal a widespread hydrological system of subglacial lakes and drainage networks beneath the Antarctic Ice Sheet which is recognized to have a large impact on the ice dynamics. The aim of this thesis is to investigate this subglacial hydrological environment and its interactions with the ice flow dynamics of the overlying ice sheet. For reaching this aim, the ice flow model RIMBAY is enhanced by a subglacial hydrology module which provides the simulation of basal water flow and the identification of positions and extents of subglacial lakes. This model is then applied to the Antarctic Ice Sheet. A subsequent validation by the analysis of ice-penetrating radar profiles in Dronning Maud Land leads to the identification of 31 new potential subglacial lake locations. Based on these findings, the total number of Antarctic subglacial lakes is estimated to be 1300±300, a factor of three more than what has been discovered so far. Their overall extent is assessed to cover about 0.6% of the Antarctic ice-bed interface. Furthermore, strong correlations are found between modeled pathways of basal water flow and observed locations of ice streams. In a detailed investigation of the Ross Ice Streams at the Antarctic Siple Coast the local basal driver of fast ice flow is identified as water saturated and unconsolidated sediment. The assessment of the basal flow regime enables the simulation of basal drainage patterns which are clearly associated ... |
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