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，基底冰架融化的实际情况、其可变性以及由于气候条件变化而可能出现的未来趋势尚不完全清楚。为了研究和了解其对南极底水组成和形成速率及其相关变率的影响，以及对全球海洋环流的影响，迫切需要更多的示踪观测。项目的目标是:A)产生一种改进实际估计的基底冰川融水库存和基底的冰架融化率(拉森冰架)西部和南部威德尔海(Filchner冰架)能够解决时间趋势futureB)跟踪基底融水的通路,它如何有助于当地南极底层水的形成,并量化相关实际南极底层水形成rates.C)进行调查,如果有证据表明冰川融化过程和相关的南极底水形成的局部变化或时间趋势。可能的变化可能与冰架的变化有关，因为拉森A、B冰架现在是无冰的，而拉森C冰架和费尔奇纳冰架都仍被冰覆盖，或者与周围水团性质或循环的变化有关。D)评估局地过程及其变率如何与盆地或全球尺度相关（例如观测到的整个盆地南极底水性质变化、变暖、变新鲜、年龄增长和通气下降、减缓人为碳吸收、体积下降、趋势）。示踪观测将在很大程度上有助于研究和量化基础冰川融化（稳定稀有气体同位素[3He， 4He, Ne]，用于量化基础冰川融水库存量）、基础融化速率和南极底水形成（瞬态微量气体[CFCs]，用于确定传输时间尺度[TTDs]、形成速率和相关的人为碳吸收）及其变异性。这些目标有助于spp1158的三个主要目标：*气候系统组分的动力学*对环境变化的响应*（威德尔海作为一个）通往低纬度的门户

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