Collaborative Research: Totten Glacier System and the Marine Record of Cryosphere - Ocean Dynamics - award 1430550

This project will investigate the marine component of the Totten Glacier and Moscow University Ice Shelf, East Antarctica. This system is of critical importance because it drains one-eighth of the East Antarctic Ice Sheet and contains a volume equivalent to nearly 7 meters of potential sea level rise, greater than the entire West Antarctic Ice Sheet. This nearly completely unexplored region is the single largest and least understood marine glacial system that is potentially unstable. Despite intense scrutiny of marine based systems in the West Antarctic Ice Sheet, little is known about the Totten Glacier system. This study will add substantially to the meager oceanographic and marine geology and geophysics data available in this region, and will significantly advance understanding of this poorly understood glacial system and its potentially sensitive response to environmental change.

Independent, space-based platforms indicate accelerating mass loss of the Totten system. Recent aerogeophysical surveys of the Aurora Subglacial Basin, which contains the deepest ice in Antarctica and drains into the Totten system, have provided the subglacial context for measured surface changes and show that the Totten Glacier has been the most significant drainage pathway for at least two previous ice flow regimes. However, the offshore context is far less understood. Limited physical oceanographic data from the nearby shelf/slope break indicate the presence of Modified Circumpolar Deep Water within a thick bottom layer at the mouth of a trough with apparent access to Totten Glacier, suggesting the possibility of sub-glacial bottom inflow of relatively warm water, a process considered to be responsible for West Antarctic Ice Sheet grounding line retreat. This project will conduct a ship-based marine geologic and geophysical survey of the region, combined with a physical oceanographic study, in order to evaluate both the recent and longer-term behavior of the glacial system and its relationship to the adjacent oceanographic system. This endeavor will complement studies of other Antarctic ice shelves, oceanographic studies near the Antarctic Peninsula, and ongoing development of ice sheet and other ocean models.

本项目将研究南极东部托滕冰川（Totten Glacier）与莫斯科大学冰架（Moscow University Ice Shelf）的海洋组分。该系统具有至关重要的研究价值：其汇水范围覆盖东南极冰盖（East Antarctic Ice Sheet）的八分之一，蕴含的冰量潜在可导致近7米的海平面上升，规模超过整个西南极冰盖（West Antarctic Ice Sheet）。这片几乎完全未被勘探的区域，是目前已知规模最大、认知程度最低的潜在不稳定海洋冰川系统。尽管学界已对西南极冰盖的海洋基底冰川系统开展了大量深入研究，但针对托滕冰川系统的相关认知仍十分匮乏。本研究将大幅补充该区域稀缺的海洋学、海洋地质与地球物理数据，显著推进对这一认知不足的冰川系统及其对环境变化潜在敏感响应的理解。

独立天基平台（space-based platforms）的监测数据显示，托滕冰川系统的质量损失正持续加速。此前针对极光冰下盆地（Aurora Subglacial Basin）的航空地球物理调查（aerogeophysical surveys）显示，该盆地拥有南极最深的冰层，且汇水流入托滕冰川系统，这为地表变化的观测结果提供了冰下环境背景，同时表明至少在两次既往冰流阶段中，托滕冰川都是最主要的汇水通道。然而，针对该区域的近海环境背景仍知之甚少。现有来自附近陆架/坡折带的有限物理海洋学（physical oceanographic）数据显示，在一条可连通托滕冰川的冰蚀槽谷口的厚层底层水中，存在改性绕极深层水（Modified Circumpolar Deep Water），这表明存在相对暖水的冰下底层流入的可能性——而该过程被认为是西南极冰盖接地线（grounding line）后退的诱因之一。本项目将开展基于科考船的该区域海洋地质与地球物理调查，并结合物理海洋学研究，以评估该冰川系统的近期与长期演化行为，及其与邻近海洋系统的相互关系。本研究将与其他南极冰架研究、南极半岛周边海洋学研究，以及当前正在推进的冰盖与其他海洋模型开发工作形成互补。