Basal glacial melting and its contribution to bottom water formation and ocean circulation in the Antarctic continental margins under changing environmental conditions.

在威德尔海，由于气候条件的变化，基座冰架融化的实际状态、其变异性和未来可能的趋势尚未完全了解。为了研究和了解其对南极底层水的组成和形成速度以及相关变异性的影响，以及对全球海洋环流的影响，迫切需要进行更多的示踪观测。拟议项目的目的是：(A)改进西部(拉森冰架)和南部韦德尔海(菲尔奇纳冰架)冰架基本冰川融化水库存和基本融化速率的实际估计数，以便能够处理未来的时间趋势；(B)追踪基本融化水的路径，它如何有助于南极当地底层水的形成，并量化相关的南极底层水实际形成速率。可能的变化可能与冰架的变化有关，因为拉森A和B现在是无冰的，而拉森C和菲尔奇纳都仍然被冰覆盖，或者与环境水团的性质或循环的变化有关。d)评估局部过程及其变异性如何与整个盆地或全球尺度有关(例如，观察到的整个盆地范围的南极底层水性质变化、变暖、淡水变暖、年龄增长和通风下降、减缓人为碳吸收、体积下降、趋势)。跟踪观测将大大有助于调查和量化基础冰川融化(稳定的稀有气体同位素[3He，4He，这些目标有助于SPP 1158的三个主要目标：*气候系统组成部分的动态变化*对环境变化的响应*(韦德尔海作为通往低纬度地区的门户)

In the Weddell Sea, the actual state of basal ice shelf melting, its variability and possible future trends due to changing climate conditions are not yet fully understood. To study and to understand its impact on the Antarctic Bottom Water composition and formation rate and related variability as well as the impact on the global ocean circulation more tracer observations are urgently needed. The aims of the proposed project are:A) To produce an improved actual estimate of basal glacial melt water inventories and basal melting rates for the ice shelves in the western (Larsen Ice Shelf) and southern Weddell Sea (Filchner Ice Shelf) to be able to address temporal trends in the futureB) To trace the pathways of the basal melt water, how it contributes to local Antarctic Bottom Water formation, and to quantify the related actual Antarctic Bottom Water formation rates.C) To investigate, if there is evidence for local shifts or temporal trends in glacial melting processes and related Antarctic Bottom Water formation. Possible changes could be related to changes in the ice shelves, as Larsen A, B are now ice free, in contrast to Larsen C and Filchner, which both are still ice covered, or to changing properties or circulation of ambient water masses.D) To assess, how local processes and their variability are related to basin wide or global scales (e.g. observed basin wide Antarctic Bottom Water property changes, warming, freshening, age increase and declining ventilation, slow down anthropogenic carbon uptake, declining volumes, trends).Tracer observations will help substantially to investigate and quantify basal glacial melting (stable noble gas isotopes [3He, 4He, Ne] to quantify basal glacial melt water inventories), basal melt rates and Antarctic Bottom Water formation (transient trace gases [CFCs] to determine transit time scales [TTDs], formation rates, and the related anthropogenic carbon uptake) and their variability.These objectives contribute to three major goals of the SPP 1158:* Dynamics of the Climate System Components* Response to Environmental Change* (The Weddell Sea as a) Gateway to Lower Latitudes