A New Instrument and Measurement Approach to Cryo-Seismogeodesy: Monitoring Antarctic Ice Shelf Stability Using Ice Penetrators

低温地震大地测量学的新仪器和测量方法：使用冰穿透器监测南极冰架稳定性

• 批准号: 1931131
• 负责人: Pedro Elosegui
• 金额: $ 86.74万
• 依托单位: Massachusetts Institute of Technology
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-08-01 至 2024-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1931131&HistoricalAwards=false
• 关键词: New; Instrument; Measurement; Approach; Cryo

Part I: Nontechnical The Antarctic continent is covered by a massive sheet of ice. The ice sheet gains mass by snowfall and losses mass by melting and calving of towering icebergs. Losses occur primarily at the ice shelves. These are where the ice sheet meets the ocean. The stability of the Antarctic land-based ice sheet depends on the stability of the oceanic ice shelves, because the ice shelves act as a buttress, restraining and modulating the amount of ice that can flow into the ocean. When ice shelves thin and weaken, as is currently observed, they can disintegrate, which leads to accelerated discharge of land-based ice to the ocean. Once the ice reaches the ocean, it contributes to accelerating sea-level rise. Thus, the Earth’s climate and the state of Antarctic ice are intimately linked through the stability of the ice shelves. It is therefore critical to understand how the Antarctic ice shelves are responding to ongoing changes in atmospheric and ocean conditions. Unfortunately, the conditions of the Antarctic environment are extreme. Deploying scientific instruments that can survive those conditions and measure the on-ice response of the shelves to forces imparted by the atmosphere is a logistics and an engineering challenge. As a result, ice-shelf measurements are sparse. These challenges can be met by developing a robust instrument that packages the desired scientific sensors into an ice penetrator that can be air dropped into remote locations on many ice shelves. This project will fuse state-of-the-art sensors that scientists use to study the physics of earthquakes and volcanoes into a single instrument that will obtain measurements pertaining to ice shelf physics. As a test to demonstrate the value of this approach, two such instruments will be dropped from a helicopter onto the Ross Ice Shelf near the US base at McMurdo, where they will collect science data for about a year, relaying the data in real time via satellite link. The project will include significant participation from undergraduate and graduate students. Part II: Technical Description Antarctic ice shelves, a critical element in the stability of the Antarctic Ice Sheet, are showing signs of rapid decline. Ice-shelf melting, retreating, and thinning lead to increased discharge of grounded ice to the ocean, and to concomitant sea-level rise. Ice-shelf disintegration could drive the Antarctic Ice Sheet to eventual collapse. Despite their key role in the future fate of the Antarctic Ice Sheet under a warming climate, ice shelves are lacking in-situ seismic and geodetic measurements. Although seismogeodetic measurements can unveil the response of the ice shelves to present-day ocean and atmospheric forcings, obtaining continuous, high-quality measurements on the Antarctic ice shelves is challenging. To address these scientific problems and tackle the observational challenges, This project will combine cryoseismology and cryogeodesy for the first time into a single instrument, a seismogeodetic ice penetrator (SGIP), that can be air-dropped onto an ice-shelf surface to help advance understanding of Antarctic ice-ocean-atmosphere dynamics. The seismogeodetic ice penetrator provides a means to efficiently observe and quantify ice-shelf stability. The seismogeodetic ice penetrator field testing will occur on the Ross Ice Shelf near McMurdo where two seismogeodetic ice penetrator units will be helicopter dropped in the first season and allowed to continuously operate over winter. A third, reference instrument will be manually implanted along an air-dropped seismogeodetic ice penetrator for ground-truthing. Science and engineering data from these instruments will be relayed over a satellite link in near-real time. The seismogeodetic ice penetrator and reference equipment will be recovered in the second season.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.

南极大陆被一片巨大的冰层覆盖着。冰盖因降雪而增加质量，因高耸冰山的融化和崩解而减少质量。损失主要发生在冰架上。这里是冰原与海洋交汇的地方。南极陆地冰盖的稳定性取决于海洋冰架的稳定性，因为冰架起着支撑作用，限制和调节流入海洋的冰的数量。当冰架变薄变弱时，就像目前观察到的那样，它们会解体，从而导致陆地上的冰加速向海洋排放。一旦冰到达海洋，就会加速海平面上升。因此，地球的气候和南极冰的状况通过冰架的稳定性紧密地联系在一起。因此，了解南极冰架如何对大气和海洋条件的持续变化作出反应是至关重要的。不幸的是，南极的环境条件是极端的。部署能够在这些条件下生存的科学仪器，并测量冰架对大气施加的力的冰上反应，是一项后勤和工程挑战。因此，冰架的测量是稀疏的。这些挑战可以通过开发一种强大的仪器来解决，该仪器将所需的科学传感器封装到一个冰穿透器中，可以空投到许多冰架的偏远地区。这个项目将把科学家们用来研究地震和火山物理的最先进的传感器融合到一个仪器中，以获得有关冰架物理的测量结果。为了证明这种方法的价值，两架这样的仪器将从一架直升机上降落到美国麦克默多基地附近的罗斯冰架上，在那里它们将收集大约一年的科学数据，并通过卫星链路实时传输数据。该项目将包括本科生和研究生的大量参与。第二部分：技术说明南极冰架是南极冰盖稳定的一个关键因素，目前有迅速下降的迹象。冰架融化、退缩和变薄导致地面冰向海洋排放的增加，并导致海平面上升。冰架的解体可能会导致南极冰盖最终崩塌。尽管在气候变暖的情况下，冰架在南极冰盖的未来命运中起着关键作用，但缺乏现场地震和大地测量。虽然大地地震测量可以揭示冰架对当今海洋和大气强迫的响应，但在南极冰架上获得连续的、高质量的测量是具有挑战性的。为了解决这些科学问题和应对观测挑战，该项目将首次将低温地震学和低温大地测量学结合到一个单一的仪器中，一个地震大地测量冰穿透器（SGIP），可以空投到冰架表面，以帮助推进对南极冰-海-大气动力学的理解。地震测冰穿透器为有效地观测和量化冰架稳定性提供了一种手段。地震测冰穿透装置现场测试将在麦克默多附近的罗斯冰架进行，在第一个季节，直升机将在那里投放两个地震测冰穿透装置，并允许在冬季持续运行。第三，参考仪器将沿着空投的地震测冰穿透器人工植入，以进行地面真相调查。来自这些仪器的科学和工程数据将通过卫星链路近乎实时地传递。地震测冰穿透器和参考设备将在第二季回收。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。