Wåhlin A K, Graham A G C, Hogan K A, Queste B Y, Boehme L, Larter R D, Pettit E C, Wellner J, Heywood K J
Department of Marine Sciences, University of Gothenburg, Box 461, 405 30 Gothenburg, Sweden.
College of Marine Science, University of South Florida, St.Petersburg, FL 33701, USA.
Sci Adv. 2021 Apr 9;7(15). doi: 10.1126/sciadv.abd7254. Print 2021 Apr.
Thwaites Glacier is the most rapidly changing outlet of the West Antarctic Ice Sheet and adds large uncertainty to 21st century sea-level rise predictions. Here, we present the first direct observations of ocean temperature, salinity, and oxygen beneath Thwaites Ice Shelf front, collected by an autonomous underwater vehicle. On the basis of these data, pathways and modification of water flowing into the cavity are identified. Deep water underneath the central ice shelf derives from a previously underestimated eastern branch of warm water entering the cavity from Pine Island Bay. Inflow of warm and outflow of melt-enriched waters are identified in two seafloor troughs to the north. Spatial property gradients highlight a previously unknown convergence zone in one trough, where different water masses meet and mix. Our observations show warm water impinging from all sides on pinning points critical to ice-shelf stability, a scenario that may lead to unpinning and retreat.
思韦茨冰川是西南极冰盖变化最迅速的冰流出口，给21世纪海平面上升预测带来了很大的不确定性。在此，我们展示了由自主水下航行器收集的关于思韦茨冰架前沿下方海洋温度、盐度和氧气的首批直接观测数据。基于这些数据，确定了流入冰下腔室的水流路径及其变化情况。中央冰架下方的深层水来自于先前被低估的一条从松岛湾进入冰下腔室的东部暖水支流。在北部的两个海底槽谷中识别出了暖水流入和富含融水的水流流出情况。空间属性梯度突出显示了一个槽谷中此前未知的汇聚区，不同水体在此交汇混合。我们的观测结果显示，暖水从各个方向冲击对冰架稳定性至关重要的固定点，这种情况可能导致冰架脱离固定并后退。
