Collaborative Research: Investigating the Role of Coastal Polynya Variability in Modulating Antarctic Marine-Terminating Glacier Drawdown

合作研究：调查沿海冰间湖变化在调节南极海洋终止冰川水位下降中的作用

• 批准号: 2205009
• 负责人: Helene Seroussi
• 金额: $ 17.54万
• 依托单位: Dartmouth College
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-09-01 至 2025-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2205009&HistoricalAwards=false
• 关键词: Collaborative; Research; Investigating; Role; Coastal

Most of the mass loss from the Antarctic Ice Sheet, a major contributor to sea level rise, occurs at its margins, where ice meets the ocean. Glaciers and ice streams flow towards the coast and can go afloat over the water, forming ice shelves. Ice shelves make up almost half of the entire Antarctic coastline, and hold back the flow of inland ice in Antarctica continent; thus they are integral to the overall stability of the Antarctic Ice Sheet. Ice shelves lose mass by two main processes: iceberg calving and basal melting. Temporal and spatial fluctuations in both are driven by various processes; a major driver of ice shelf melt is the heat provided by the neighboring Southern Ocean. Ocean heat, in turn, is driven by various aspects of the ice shelf environment. One of the most significant contributors to changes in the ocean’s heat content is the presence of sea ice. This research will focus on the effects of coastal polynyas (areas of open water amidst sea ice), how they modulate the local ocean environment, and how that environment drives ice shelf basal melting. To date, the relationship between polynyas and ice shelf melt has not been characterized on an Antarctic-wide scale. Understanding the feedbacks between polynya size and duration, ocean stratification, and ice shelf melt, and the strength of those feedbacks, will improve the ability to characterize influences on the long-term stability of ice shelves, and in turn, the Antarctic Ice Sheet as a whole. A critical aspect of this study is that it will provide a framework for understanding ice shelf-ocean interaction across a diverse range of geographic settings. This, together with improvements of various models, will help interpret the impacts of future climate change on these systems, as their responses are likely quite variable and, overall, different from the large-scale response of the ice sheet. This project will also provide a broader context to better design future observational studies of specific coastal polynya and ice shelf processes.This study focuses on four main hypotheses: 1) Variations of coastal polynya extent are correlated with those of the ice shelf melt rates, and this correlation varies around Antarctica; 2) Polynya extent modulates a feedback between ice shelf melt and accretion regimes through stratification of local waters; 3) Polynya extent together with seafloor bathymetry regulate the volume of warm offshore waters that reach ice margins; and 4) The strength of the feedback between polynya and glacier ice varies with geographic setting and influences the long-term stability of the glacial system. Observational data, including ice-penetrating radar, radar and laser altimetry, and in situ hydrographic data, and derived data sets from the Southern Ocean State Estimate (SOSE) project and BedMachine Antarctica, will be used in conjunction with ocean (MIT global circulation model, MITgcm) and ice sheet (Ice sheet and Sea-level System Model, ISSM) models to reveal underlying dynamics. The joint analysis of the observational data enables an investigation of polynya, ocean, and ice shelf signals and their interplay over time across a range of settings. The results of this data analysis also provide inputs and validation data for the modeling tasks, which will allow for characterization of the feedbacks in our observations. The coupled modeling will enable us to examine the interaction between polynya circulation and ice shelves in different dynamical regimes and to understand ice and ocean feedback over time. Diagnosing and interpreting the pan-Antarctic spatial variability of the polynya-ice shelf interaction are the main objectives of this research and separates this study from other projects targeted at the interactive processes in specific regions. As such, this research focuses on seven preliminary target sites around the Antarctic coast to establish a framework for interpreting coupled ice shelf-ocean variability across a diverse range of geographic settings.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

来自南极冰盖的大部分质量损失是海平面上升的主要贡献者，发生在其冰与海洋相遇的边缘。冰川和冰流流向海岸，可以在水上漂浮，形成冰架。冰架几乎构成了整个南极海岸线的一半，并阻止了南极大陆的内陆冰流；因此，它们是南极冰盖的整体稳定性的组成部分。冰架通过两个主要过程失去质量：冰山产犊和基本融化。两者中的时间和空间波动均由各种过程驱动；冰架融化的主要驾驶员是邻近南大洋提供的热量。反过来，海火是由冰架环境的各个方面驱动的。海冰的存在是海冰的存在。这项研究将重点介绍沿海波利亚斯（海冰中的开放水域）的影响，它们如何调节当地的海洋环境以及该环境如何驱动冰架基本融化。迄今为止，波利尼亚和冰架熔体之间的关系尚未在南极范围内表征。了解Polynya尺寸和持续时间，海洋分层和冰架融化之间的反馈以及这些反馈的强度将提高表征对冰架长的影响的能力，进而将南极冰盖整个。这项研究的一个关键方面是，它将提供一个框架，以理解在各种地理环境中的冰架 - 海洋相互作用。这将与各种模型的改进一起，有助于解释未来气候变化对这些系统的影响，因为它们的响应可能会发生变化，而且总体上与冰盖的大规模响应不同。该项目还将提供更广泛的背景，以更好地设计对特定沿海Polynya和Ice架过程的未来观察性研究。这项研究重点介绍了四个主要假设：1）沿海Polynya范围的变化与冰架融化速率的变化相关，而该相关性范围围绕南极洲范围； 2）Polynya范围通过当地水的分层调节冰架融化与积聚方案之间的反馈； 3）Polynya范围与海底测深量法调节，温暖的近海水域达到冰缘； 4）Polynya和冰川冰品种之间具有地理环境的反馈强度，并影响冰川系统的长期稳定性。观察数据，包括冰根化辐射，雷达和激光高度测定，以及原位水文数据，以及来自南海洋州估计（SOSE）项目（SOSE）项目和Bedmachine Antarctica的派生数据集，将与海洋（MIT循环模型，MITGCM，MITGCM）和ICE平板（ICE SEAPPLED MANDERS和SEAPLED SYSTER模型）一起使用，用于海洋（MIT循环模型）。观察数据的联合分析使Polynya，Ocean和Ice Beshelf信号及其在各种环境中的相互作用进行投资。此数据分析的结果还为建模任务提供了输入和验证数据，这将允许在我们的观察中表征反馈。耦合的建模将使我们能够在不同的动态机制下检查Polynya循环和冰架之间的相互作用，并随着时间的推移了解冰和海洋的反馈。诊断和解释Polynya-Ice货架相互作用的泛抗性空间变异性是本研究的主要目标，并将这项研究与针对特定区域交互过程的其他项目分开。因此，这项研究的重点是南极海岸周围的七个初步目标站点，以建立一个框架，以解释潜水员的地理环境范围内耦合的冰架 - 海洋可变性。该奖项反映了NSF的法定任务，并被认为是通过使用该基金会的知识分子和更广泛影响的评估来评估CRITERIA的评估来通过评估来珍贵的支持。