Melting and Calving of Antarctic Ice Shelves

南极冰盖的大部分漂浮在周围的海洋中，处于海洋学和冰川学的物理和智力边界上。这些冰架不断地通过融化进入海洋而失去质量，并周期性地因冰山的崩解而失去质量。这些损失通过地面冰的外流、地表积累和基础冻结来补偿。冰架的源和汇在几个时间尺度上各不相同，但它们的损耗条件尚不为人所知。关于冰架大幅后退、区域海洋清新以及冰速和变薄的报道尤其令人担忧，因为目前有很深的冰川接地线水域的海洋温度正在变暖。该奖项支持一项关于南极冰架损耗的研究，该研究使用最新的海洋地球化学测量结果，并利用数值模拟和遥感资源。与哥伦比亚大学和英国南极调查局的同事合作，将使用对氯氟烃、氦、霓虹灯和氧同位素的测量来推断罗斯冰架下的基底融化，并将结合海洋学和高度计数据来调查乔治六世冰架的物质平衡。海洋和遥感观测也将被用来帮助完善冰洞环流的数值模型。其目的是减少基础融化和冻结的不同估计之间的不确定性，评估区域可变性，并更新早期对环极净融化的评估。更好地了解冰架磨损对于更好地了解冰架对气候变化的反应至关重要。大型冰架崩解事件可能会改变海洋环流和海冰形成，并可能导致物流问题，如最近在罗斯海经历的那样。更广泛的影响包括冰架融水在清新和稳定上层海洋方面的作用，以及南极底层水的形成，这种水可以追溯到遥远的北大西洋。就冰架磨损影响地面冰流动的程度而言，这项工作对冰盖的稳定性和海平面上升也有影响。

Major portions of the Antarctic Ice Sheet float in the surrounding ocean, at the physical and intellectual boundaries of oceanography and glaciology. These ice shelves lose mass continuously by melting into the sea, and periodically by the calving of icebergs. Those losses are compensated by the outflow of grounded ice, and by surface accumulation and basal freezing. Ice shelf sources and sinks vary on several time scales, but their wastage terms are not yet well known. Reports of substantial ice shelf retreat, regional ocean freshening and increased ice velocity and thinning are of particular concern at a time of warming ocean temperatures in waters that have access to deep glacier grounding lines.This award supports a study of the attrition of Antarctic ice shelves, using recent ocean geochemical measurements and drawing on numerical modeling and remote sensing resources. In cooperation with associates at Columbia University and the British Antarctic Survey, measurements of chlorofluorocarbon, helium, neon and oxygen isotopes will be used to infer basal melting beneath the Ross Ice Shelf, and a combination of oceanographic and altimeter data will be used to investigate the mass balance of George VI Ice Shelf. Ocean and remote sensing observations will also be used to help refine numerical models of ice cavity circulations. The objectives are to reduce uncertainties between different estimates of basal melting and freezing, evaluate regional variability, and provide an update of an earlier assessment of circumpolar net melting.A better knowledge of ice shelf attrition is essential to an improved understanding of ice shelf response to climate change. Large ice shelf calving events can alter the ocean circulation and sea ice formation, and can lead to logistics problems such as those recently experienced in the Ross Sea. Broader impacts include the role of ice shelf meltwater in freshening and stabilizing the upper ocean, and in the formation of Antarctic Bottom Water, which can be traced far into the North Atlantic. To the extent that ice shelf attrition influences the flow of grounded ice, this work also has implications for ice sheet stability and sea level rise.