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状况、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未得到充分了解。为了研究和了解其对南极底层水组成和形成速率及其相关变化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。拟议项目的目标是：A） 对西部（拉森冰架）和南部威德尔海（菲尔希纳冰架）冰架的基底冰川融水存量和基底融水速率进行改进的实际估计，以便能够处理未来的时间趋势B） 追踪基底融水的路径，它如何有助于南极底层水的形成，并量化相关的实际南极底层水形成率。 调查是否有证据表明冰川融化过程和相关的南极底层水形成存在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Larsen A，B现在没有冰，而Larsen C和Filchner仍然被冰覆盖，或者与环境水体的性质或循环变化有关。 评估当地过程及其变异性与流域范围或全球尺度的关系（例如，观测到的整个流域南极底层水性质的变化、变暖、变淡、年龄增加和通风下降、人为碳吸收减缓、体积下降、趋势）。（稳定的稀有气体同位素[3He，4He，Ne]，用于量化基底冰川融水的总量）、基底融水速率和南极底层水的形成（瞬态痕量气体[CFC]，以确定过渡时间尺度[TTD]，形成率，以及相关的人为碳吸收量）及其变异性。这些目标有助于实现SPP 1158的三个主要目标：* 气候系统各组成部分的动力学 * 应对环境变化 * (The威德尔海（Weddell Sea）作为通往下南极洲的门户

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