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，南极冰盖下的冰下环境与大气环境是隔绝的，对这一边界层的物理条件的了解仍然相当有限。由于冰盖厚度大，许多地区冰盖底部的冰温达到压力熔点，近年来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，而且对极端环境中生命形式的潜在来源。拟议的项目旨在提供几个主要问题的答案，这些问题与冰下水体、冰盖底部和冰盖边界的上覆冰和排水之间的相互作用有关。提出了一种具有挑战性的方法来耦合现有的高分辨率冰动力和冰下湖环流数值模型。这将通过开发将排水机制实现到耦合模型中的方法来完成。为了对沃斯托克冰下湖最著名的冰湖系统进行可靠性评估，我们付出了相当大的努力。有了可用的数值模式系统，就可以解决许多非常重要的问题，这些问题对于评估南极冰盖最近和未来的物理/动力状况至关重要。也就是说，将调查冰下水体与冰盖动态状况的相关性，从大型冰下湖泊开始，一直到当地的排水系统。此外，本项目还将研究湖泊存在对冰流发生的意义，以及冰下大水爆发对邻近海洋环流的影响。综合所研究的机制及其影响将使人们对南极冰盖大部分地区的动态状况和敏感性有一个全新的认识。

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.