Glacial Meltwater Identification in the Amundsen Sea

Pine Island Ice Shelf, in the Amundsen Sea, is losing mass because of warm ocean waters melting the ice from below. Tracing meltwater pathways from ice shelves is important for identifying the regions most affected by the increased input of this water type. Here, optimum multiparameter analysis is used to deduce glacial meltwater fractions from water mass characteristics (temperature, salinity, and dissolved oxygen concentrations), collected during a ship-based campaign in the eastern Amundsen Sea in February-March 2014. Using a one-dimensional ocean model, processes such as variability in the characteristics of the source water masses on shelf and biological productivity/respiration are shown to affect the calculated apparent meltwater fractions. These processes can result in a false meltwater signature, creating misleading apparent glacial meltwater pathways. An alternative glacial meltwater calculation is suggested, using a pseudo-Circumpolar Deep Water endpoint and using an artificial increase in uncertainty of the dissolved oxygen measurements. The pseudo-Circumpolar Deep Water characteristics are affected by the under ice shelf bathymetry. The glacial meltwater fractions reveal a pathway for 2014 meltwater leading to the west of Pine Island Ice Shelf, along the coastline.

位于阿蒙森海中的松岛冰架由于温暖的海水从下方融化冰层而正在失去质量。追踪冰架的融水路径对于确定受这种水类型输入增加影响最大的区域非常重要。在此，利用最优多参数分析从水体特征（温度、盐度和溶解氧浓度）推断冰川融水比例，这些数据是在2014年2月 - 3月在阿蒙森海东部的一次船基考察中收集的。利用一维海洋模型，表明诸如陆架上源水团特征的变化以及生物生产力/呼吸作用等过程会影响计算出的表观融水比例。这些过程可能导致错误的融水特征，产生误导性的表观冰川融水路径。建议采用一种替代的冰川融水计算方法，即使用一个伪绕极深层水端点，并人为增加溶解氧测量的不确定性。伪绕极深层水的特征受冰架下的地形影响。冰川融水比例揭示了2014年融水沿着海岸线通向松岛冰架西部的一条路径。