NSFPLR-NERC: Melting at Thwaites grounding zone and its control on sea level (THWAITES-MELT)

NSFPLR-NERC：思韦茨接地区的融化及其对海平面的控制（THWAITES-MELT）

基本信息

批准号：
NE/S006427/1
负责人：
Matthew Piggott
金额：
$ 26.25万
依托单位：
Imperial College London
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2018
资助国家：
英国
起止时间：
2018 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FS006427%2F1
关键词：
NSFPLR NERC Melting Thwaites grounding

项目摘要

The fate of the West Antarctic Ice Sheet (WAIS) is one of the largest uncertainty in projections of sea-level rise. ThwaitesGlacier (TG) is a primary contributor to sea-level rise and its flow is accelerating. This faster flow is a response to reducedbuttressing from its thinning, floating ice shelf, and is ultimately caused by ocean-driven melting. The degree to which costlyand geopolitically-challenging sea-level rise will occur therefore hangs to a large extent on ice-ocean interaction beneathAntarctic ice shelves. However, the Thwaites system is not sufficiently well understood, exposing a significant gap in ourunderstanding of WAIS retreat, its ocean-driven forcing, and the consequences for sea level.The chief regulators of TG's retreat are ice and ocean processes in its grounding zone, where the ice flowing from inlandgoes afloat. Ice and ocean processes at this precise locale are central to our understanding of marine ice-sheet instability,yet key variables have not been constrained by observation. The problem is compounded because oceanic melt occurspreferentially in the deep, narrow cavity in the grounding zone, where physical descriptions of the processes driving melt are unverified.These gaps in knowledge are damaging because model projections of TG's future display extreme sensitivity to melting inthe grounding zone and how that melting is applied. Equally-credible melt rates and grounding-zone glaciologicaltreatments yield divergent trajectories for the future of West Antarctica, ranging from little change to large-scale ice sheetcollapse with a half a meter or more of sea-level rise. The enormous uncertainty in outcome stems from the lack ofobservations in this critical region.This project will observe, quantify and model the Thwaites ice-ocean system in the grounding zone, to firmly establish thephysics linking ocean forcing and ice-sheet response. The time-dependent cavity will be thoroughly surveyed andinstrumented with ocean monitoring devices. Melting will be observed by a network of autonomous sensors and from spaceover an extended period. The response of the glacier will also be observed. Our enhanced understanding of meltingbeneath TG's ice shelf, its grounding zone and its connection with the glacier flow will be built into state-of-the-art coupledice sheet and ocean models. These physics-rich, high-resolution models will allow the potential sea-level contribution of TGto be bounded with unprecedented fidelity.We propose a suite of integrated activities: (1) multi-year oceanographic time series from beneath TG's ice shelf to quantifymelting processes that need inclusion in ocean models, (2) analogous measurements on the glacier to validate processesgoverning grounding-line retreat, (3) coupling of these in situ measurements with novel, high-resolution space-borneobservations, (4) building this new understanding into state-of-the-art ocean and ice sheet models to correctly simulate theTG system, (5) coupling the models and running with realistic present-day ocean forcing to project the state of TG basinover the next hundred years . The international team will consist of experienced marine and glacier scientists using a rangeof techniques, from the well-established through to the cutting-edge. The outcome of the project will be a thoroughunderstanding of the TG system in the critical zone extending from a few kilometers inland of the grounding line, throughthe grounding zone, and out under the ice shelf.

南极西部冰盖（WAIS）的命运是海平面上升预测中最大的不确定性之一。思韦茨冰川 (TG) 是海平面上升的主要原因，而且其流量正在加速。这种更快的流动是对其变薄的浮动冰架支撑减少的反应，最终是由海洋驱动的融化造成的。因此，代价高昂且具有地缘政治挑战性的海平面上升的程度在很大程度上取决于南极冰架下冰海的相互作用。然而，人们对 Thwaites 系统的了解还不够充分，这使得我们对 WAIS 撤退、其海洋驱动力以及对海平面的影响的理解存在重大差距。TG 撤退的主要调节者是其接地区的冰和海洋过程，从内陆流出的冰漂浮在那里。这一精确地点的冰和海洋过程是我们了解海洋冰盖不稳定性的核心，但关键变量尚未受到观测的限制。这个问题变得更加复杂，因为海洋融化主要发生在接地区又深又窄的空腔中，而驱动融化过程的物理描述尚未得到验证。这些知识差距具有破坏性，因为 TG 未来的模型预测对接地区的融化极其敏感。以及如何应用这种熔化。同样可信的融化速度和接地区冰川处理为西南极洲的未来带来了不同的轨迹，从微小变化到大规模冰盖崩塌，海平面上升半米或更多。结果的巨大不确定性源于缺乏对该关键区域的观测。该项目将对接地区的思韦茨冰海系统进行观测、量化和建模，以牢固地建立联系海洋强迫和冰盖响应的物理原理。与时间相关的空腔将被彻底调查并配备海洋监测设备。自主传感器网络将在很长一段时间内从太空观测融化情况。冰川的反应也将被观察到。我们对 TG 冰架下方融化、其接地区及其与冰川流的联系的深入了解将被纳入最先进的耦合冰盖和海洋模型中。这些物理丰富的高分辨率模型将使 TG 对海平面的潜在贡献以前所未有的保真度受到限制。我们提出了一系列综合活动：（1）从 TG 冰架下方进行多年海洋学时间序列，以量化融化过程需要纳入海洋模型，(2) 对冰川进行类似测量，以验证控制接地线撤退的过程，(3) 将这些现场测量与新颖的高分辨率相结合星载观测，(4) 将这种新的理解构建到最先进的海洋和冰盖模型中，以正确模拟 TG 系统，(5) 耦合模型并与现实的当今海洋强迫一起运行，以预测TG盆地未来百年。国际团队将由经验丰富的海洋和冰川科学家组成，他们使用一系列技术，从成熟的技术到尖端的技术。该项目的成果将是对从接地线内陆几公里处延伸、穿过接地区一直到冰架下的关键区域的TG系统的彻底了解。