NSFGEO-NERC: Understanding the Response to Ocean Melting for Two of East Antarctica's Most Vulnerable Glaciers: Totten and Denman

NSFGEO-NERC：了解南极洲东部两个最脆弱的冰川：托滕冰川和登曼冰川对海洋融化的反应

• 批准号: 2231230
• 负责人: Ian Joughin
• 金额: $ 57.56万
• 依托单位: University of Washington
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-08-15 至 2026-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2231230&HistoricalAwards=false
• 关键词: NSFGEO; NERC; Understanding; Response; Ocean

The snow that falls on Antarctica compresses to ice that flows toward the coast as a large sheet, returning it to the ocean over periods of centuries to millennia. In many places around Antarctica, the ice sheet extends from the land to over the ocean, forming floating ice shelves on the periphery. If this cycle is in balance, the ice sheets help maintain a stable sea level. When the climate cools or warms, however, sea level falls or rises as the ice sheet gains or loses ice. The peripheral ice shelves are important for regulating sea level because they help hold back the flow of ice to the ocean. Warming ocean waters thin ice shelves by melting their undersides, allowing ice to flow faster to the ocean, and raising sea level globally. Thus, an important question is how much sea level will rise in response to warming ocean temperatures over the next century(s) that further thin Antarctica’s ice shelves. Currently, West Antarctica produces the majority of the continent’s contribution to sea level. Albeit with large uncertainty, ice-sheet models indicate that Totten and Denman glaciers in East Antarctica could also produce substantial sea-level rise in the next century(s). This international study will focus on improving understanding of how much these glaciers will contribute to sea level under various warming scenarios.The project will use numerical models constrained by oceanographic and remote sensing observations to determine how Totten and Denman glaciers will respond to increased melting. Remote sensing data will provide updated and improved estimates of the melt rate for each ice shelf. Two float profilers will be deployed from aircraft by British and Australian partners in front of each ice shelf to repeatedly measure the temperature and salinity of the water column, with the results telemetered back via satellite link. The melt and oceanographic data will be used to constrain parameterized transfer functions for ice-shelf cavity melting in response to ocean temperature, improving on current parameterizations based on limited data. These melt functions will be used with ocean temperatures from climate models to force an open-source ice-flow numerical model for each glacier to determine the century-scale response for a variety of scenarios, helping to reduce uncertainty in sea level contributions from this part of Antarctica. Processes other than melt that might further alter the contribution to sea level over the next few centuries will also be examined. On the observational side, the demonstrated deployment of float profilers from a sonobuoy launch tube in polar settings would help raise the technology readiness of operational in-situ monitoring of the rapidly changing polar shelf seas, paving the way for an expansion of observations of ocean hydrographic properties from remote areas that currently are poorly understood. In addition to being of scientific value, reduced uncertainty in sea-level rise projections has strong societal benefit to coastal communities struggling with long-range planning to mitigate the effects of sea-level rise over the coming decades to centuries. Outreach activities by team members will help raise public awareness of Antarctica's dramatic changes and the resulting consequences. This is a project jointly funded by the National Science Foundation’s Directorate for Geosciences (NSF/GEO) and the National Environment Research Council (NERC) of the United Kingdom (UK) via the NSF/GEO-NERC Lead Agency Agreement. This Agreement allows a single joint US/UK proposal to be submitted and peer-reviewed by the Agency whose investigator has the largest proportion of the budget. Upon successful joint determination of an award recommendation, each Agency funds the proportion of the budget that supports scientists at institutions in their respective countries.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.

福尔斯降落在南极洲的雪压缩成冰，作为一个大的床单流向海岸，在几个世纪到几千年的时间里返回海洋。在南极洲周围的许多地方，冰盖从陆地延伸到海洋上方，在外围形成漂浮的冰架。如果这个循环是平衡的，冰盖有助于保持稳定的海平面。然而，当气候变冷或变暖时，海平面福尔斯会随着冰盖增加或减少冰而下降或上升。外围冰架对调节海平面非常重要，因为它们有助于阻止冰流入海洋。温暖的海洋沃茨通过融化其底部的薄冰架，使冰更快地流向海洋，并提高全球海平面。 因此，一个重要的问题是，在下一个世纪，随着海洋温度的升高，南极洲的冰架会进一步变薄，海平面会上升多少。 目前，西南极洲产生了该大陆对海平面的大部分贡献。尽管有很大的不确定性，冰盖模型表明，南极洲东部的托滕和登曼冰川也可能在下一个世纪造成海平面大幅上升。这项国际研究将侧重于提高对这些冰川在各种变暖情景下对海平面的贡献程度的认识。该项目将使用受海洋学和遥感观测约束的数值模型，以确定托滕和登曼冰川将如何对融化加剧作出反应。 遥感数据将提供关于每个冰架融化速度的最新和改进的估计。英国和澳大利亚的合作伙伴将在每个冰架前从飞机上部署两个浮标剖面仪，反复测量水柱的温度和盐度，并通过卫星链路将结果遥测回来。融化和海洋学数据将被用来约束参数化的传递函数，用于冰架空洞融化对海洋温度的反应，改善目前基于有限数据的参数化。这些融化函数将与来自气候模型的海洋温度一起使用，以迫使每个冰川的开源冰流数值模型确定各种情景的世纪尺度响应，帮助减少南极洲这一部分海平面贡献的不确定性。除融化外，还将研究可能在未来几个世纪进一步改变海平面变化的其他过程。在观测方面，示范性地在极地环境中从声纳浮标发射管部署浮标剖面仪，将有助于提高对迅速变化的极地大陆架海域进行实地监测的技术准备程度，为扩大对目前知之甚少的偏远地区海洋水文特性的观测铺平道路。除了具有科学价值外，减少海平面上升预测的不确定性，对正在努力进行长期规划以减轻未来几十年至几个世纪海平面上升影响的沿海社区也有很大的社会效益。考察队成员的外联活动将有助于提高公众对南极洲巨大变化及其后果的认识。这是一个由国家科学基金会地球科学理事会（NSF/GEO）和联合王国国家环境研究理事会（NERC）通过NSF/GEO-NERC牵头机构协议联合资助的项目。该协议允许美国/英国提交一份联合提案，并由研究者拥有最大预算比例的机构进行同行评审。一旦成功地共同确定了奖励建议，每个机构将资助各自国家机构科学家的预算比例。该奖项反映了NSF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。