Collaborative Research: Investigating Four Decades of Ross Ice Shelf Subsurface Change with Historical and Modern Radar Sounding Data

合作研究：利用历史和现代雷达探测数据调查罗斯冰架地下四个十年的变化

• 批准号: 2049332
• 负责人: Wing Yin Chu
• 金额: $ 40.13万
• 依托单位: Georgia Tech Research Corporation
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-08-15 至 2024-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2049332&HistoricalAwards=false
• 关键词: Collaborative; Research; Investigating; Four; Decades

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2).Ice shelves play a critical role in restricting the seaward flow of grounded glacier ice by providing buttressing at their bases and sides. Processes that affect the long-term stability of ice shelves can therefore influence the future contribution of the Antarctic Ice Sheet to global sea-level rise. The Ross Ice Shelf is the largest ice shelf on Earth, and it buttresses massive areas of West and East Antarctica. Previous studies of modern ice velocity indicated that the Ross Ice Shelf’s mass loss is roughly balanced by its mass gain. However, more recent work that extends further back in time reveals the ice shelf is likely not in steady state, with possible long-term thinning since the late 1990s. Consequently, to accurately interpret modern-day ice-shelf changes, long-term observations are critical to evaluate how these recent variations fit into the historical context of ice-shelf variability. This project will examine more than four decades of historical and modern airborne radar sounding observations of the Ross Ice Shelf (spanning 1971 to 2017) to investigate ice-shelf changes on decadal timescales. The team will process, calibrate, and analyze radar data collected during 1971-79 field campaigns and compare them against modern observations collected between 2011-17. They will estimate basal melt rates by examining changes in ice-shelf thickness, and will determine other important metrics for melt, including ice-shelf roughness, englacial temperature, and marine-ice formation. The project will support the education of a Ph.D. student at each of the three participating institutions. In addition, the project will support the training of undergraduate and high-school researchers in radioglaciology and Antarctic sciences.The project will test the hypothesis that, over decadal timescales, the basal melt rates beneath the Ross Ice Shelf have been low, particularly under shallow ice drafts, leading to overall thickening and increased buttressing potential. The team aims to provide a direct estimate of basal melt rates based on changes in ice-shelf thickness that occurred between 1971 and 2017. This project will extend similar work completed at Thwaites Glacier and improve the calibration methods on the vertical scaling for fast-time and depth conversion. The work will also leverage the dense modern surveys to improve the geolocation of radar film collected on earlier field campaigns to produce a more precise comparison of local shelf thickness with the modern data. In addition, the team will conduct englacial attenuation analysis to calculate englacial temperature to infer the trends in local basal melting. They will also examine the radiometric and scatterometric character of bed echoes at the ice-ocean boundary to characterize changes in ice-shelf basal roughness, marine-ice formation related to local basal freezing, and structural damage from fracture processes.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.

该奖项是根据2021年《美国救援计划法》（公法117-2）全部或部分资助的。ICE货架在限制接地冰川冰的海流方面起着至关重要的作用，通过在其基地和侧面提供支撑。因此，影响冰架长期稳定性的过程会影响南极冰盖对全球海平面上升的未来贡献。罗斯冰架是地球上最大的冰架，它支持西南极和东部东部的巨大地区。先前对现代冰速度的研究表明，罗斯冰架的质量损失与质量增益大致平衡。但是，最近的工作延伸到及时延伸，这表明冰架可能不处于稳定状态，自1990年代后期以来可能会长期变化。因此，为了准确解释现代的冰井变化，长期观察对于评估这些最近的变化如何符合冰壳可变性的历史背景至关重要。该项目将检查超过四十年的历史和现代空中雷达对罗斯冰架（Spanning 1971至2017年）的观察，以调查衰老时标的冰架变化。该团队将处理，校准和分析在1971 - 79年的现场活动期间收集的雷达数据，并将其与2011 - 17年之间收集的现代观察结果进行比较。他们将通过检查冰架厚度的变化来估计基本熔体速率，并确定熔体的其他重要指标，包括冰架粗糙度，工程师温度和海洋冰形成。该项目将支持博士学位的教育。在三个参与机构中的每个机构中的每个学生。此外，该项目将支持对放射性学和南极科学领域的本科和高中研究人员的培训。该项目将检验以下假设：在衰老的时间尺度上，罗斯冰架下的基本融化速率较低，尤其是在浅层冰上，导致了整体增厚和增强的潜力。该团队的目标是基于1971年至2017年之间发生的冰架厚度的变化来直接估算基本熔体速率。该项目将扩展在Thwaites Glacier完成的类似工作，并改善垂直缩放的校准方法，以进行快速和深度转换。这项工作还将利用密集的现代调查来改善在早期现场活动中收集的雷达膜的地理位置，以对当地架子厚度与现代数据进行更精确的比较。此外，团队将进行工程师衰减分析，以计算工程师的温度，以推断当地基本熔化的趋势。 They will also examine the radiometric and scatterometric character of bed echoes at the ice-ocean boundary to characterize changes in ice-shelf basic roughness, marine-ice formation related to local basal freezing, and structural damage from fracture processes.This award reflects NSF's statutory mission and has been deemed precious of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.