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知识边界。这些冰架通过融化到海里而不断地失去质量，并通过冰山的崩解而周期性地失去质量。这些损失由地面冰的流出以及表面积累和底部冻结来补偿。 冰架的源和汇在几个时间尺度上变化，但它们的损耗项尚不清楚。 关于冰架大幅度后退、区域性海洋淡化和冰速增加及变薄的报告，在有深冰川接地线的沃茨的海洋温度正在变暖的时候，特别令人关切，该奖项支持利用最近的海洋地球化学测量结果并利用数值模拟和遥感资源，对南极冰架的损耗进行研究。 将与哥伦比亚大学和英国南极调查局的同事合作，利用氯氟烃、氦、氖和氧同位素的测量结果推断罗斯冰架底部的融化情况，并将利用海洋学和高度计数据相结合的方法调查乔治六世冰架的物质平衡。 海洋和遥感观测也将用于帮助改进冰腔环流的数值模型。 其目的是减少不同估计的基础融化和冻结之间的不确定性，评估区域的变化，并提供一个更新的环极净融化的早期评估。更好地了解冰架磨损是必不可少的，以提高对气候变化的冰架响应的理解。大规模的冰架断裂事件会改变海洋环流和海冰的形成，并可能导致物流问题，例如最近在罗斯海经历的问题。 更广泛的影响包括冰架融水在更新和稳定上层海洋方面的作用，以及在形成南极底层水方面的作用，这些底层水可以追溯到北大西洋。在冰架磨损影响地面冰流动的程度上，这项工作也对冰盖稳定性和海平面上升有影响。

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.