The impact of subglacial hydrology and ice water interaction on the ice dynamics of Antartica: subglacial lakes and drainage systems

在很长一段时间里，南极冰盖下的冰下制度与大气环境隔绝，对这一边界层的物理条件的了解仍然相当有限。由于冰层厚度大，冰盖底部的冰温在许多地区达到压力融点，最近在南极冰盖下发现了大量的冰下湖泊和丰富的水。这一事实有许多重要的后果，例如，对冰盖的动态条件，但对极端环境中的潜在生命形式来源也有影响。拟议的项目旨在就与冰下水体、上覆冰和冰盖底部和跨冰盖边界的排水之间的相互作用有关的几个主要问题提供答案。提出了一种具有挑战性的方法，用于将现有的高分辨率冰动力学数值模式与冰下湖泊环流相结合。这将通过制定在耦合模式中实施排水机制的手段来完成。为了评估最著名的冰下沃斯托克湖冰湖系统的模型的可靠性，人们做出了相当大的努力。有了一个有效的数值模式系统，将解决一些非常重要的问题，这些问题对于评估南极冰盖最近和未来的物理/动力条件至关重要。也就是说，将调查冰下水体与冰盖动态情况的相关性，从大型冰下湖泊开始，向下延伸到当地的排水系统。此外，该项目还将研究湖泊的存在对冰流开始的意义，以及主要的冰下水爆发对邻近海洋环流的影响。对所调查的机制及其影响的综合将为了解南极冰盖大部分的动态状态和敏感性提供全新的视角。

For a very long time the subglacial regime underneath the Antarctic Ice Sheet was isolated from the atmospheric environment and there is still only rather limited knowledge about the physical conditions in this boundary layer. Due to the large ice thicknesses ice temperatures at the ice sheet bottom reach the pressure melting point in many regions, and recently a large number of subglacial lakes and abundant water was detected underneath the Antarctic Ice Sheet. This fact has a number of important consequences, e.g., on the dynamic conditions of the ice sheet, but also for potential sources of life forms in extreme environments. The proposed project aims on providing answers on several of the major issues connected with the interaction between subglacial water bodies, the overlying ice and drainage at the ice sheet bottom and across the ice sheet's boundaries. A challenging approach is proposed for the coupling of already existing numerical models of highresolution ice dynamics and subglacial lake circulation. This will be completed by developing means for the implementation of drainage mechanisms into the coupled model. A considerable effort is taken in order to evaluate the models reliability for the best known ice-lake system of subglacial Lake Vostok. With a working numerical model system at hand a number of very important questions will be tackled which are crucial for evaluating the recent and future physical/dynamical condition of the Antarctic Ice Sheet. Namely, the relevance of subglacial water bodies for the dynamic situation of the ice sheet will be investigated, starting from large subglacial lakes and reaching down to local drainage systems. Also the significance of lake existance for the onset of ice streams and the influence of major subglacial water bursts on the adjacent oceanic circulation will be investigated within this project. A synthesis of the investigated mechanisms and their impacts will provide a totally new insight into the dynamic status and the sensitivity of large parts of the Antarctic Ice Sheet.