Collaborative Research: Topographic Controls on Antarctic Ice Sheet Grounding Line Behavior - Integrating Models and Observations

目前南极洲的冰量损失主要是由冰川接地线的变化驱动的，在那里，内陆冰从接地过渡到漂浮在海洋中。在这种情况下，冰川退缩的速度和模式被认为是由冰下的地形控制的。该项目将过去冰退缩事件的证据和其他实地数据，如接地线位置和日期，冰下地形和融水特征，纳入冰流的数值模型，以调查接地线过程和冰下地形对过去15年冰川退缩率的影响，最近的观测表明，南极冰量的损失主要是由接地线或接地线附近的扰动驱动的。然而，由于缺乏关于冰下和接地线环境的资料，对质量损失和海平面上升的预测存在很大的不确定性。该项目将把冰川消退大陆架的地质数据纳入复杂程度从一维到三维不等的数字模型。南极洲的数值冰盖模型很少在过去的15,000年（这一时期跨越了自末次冰盛期以来南极大陆架的冰川消退）中对动力学有多重约束。 地质约束包括接地线的位置，冰消年表，接地线冰架过程的信息。 这些模型将用于调查满足地质限制的必要扰动和控制。将古冰行为的地质重建与冰响应的数值模型相结合的多学科方法将使研究小组能够测试对冰下控制对接地线动力学的理解，并评估现代接地线的稳定性。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估来支持。

Current ice mass loss in Antarctica is largely driven by changes at glacier grounding lines, where inland ice transitions from being grounded to floating in the ocean. The rate and pattern of glacier retreat in these circumstances is thought to be controlled by the terrain under the ice. This project incorporates evidence of past ice-retreat events and other field data, such as grounding-line positions and dates, subglacial topography, and meltwater features, into numerical models of ice flow to investigate the influence that grounding-line processes and subglacial topography have on glacier retreat rates over the past 15,000 years.Recent observations suggest that Antarctic ice mass loss is largely driven by perturbations at or near the grounding line. However, the lack of information on subglacial and grounding-line environments causes large uncertainties in projections of mass loss and sea-level rise. This project will integrate geologic data from the deglaciated continental shelf into numerical models of varying complexity from one to three-dimensions. Rarely do numerical ice-sheet models of Antarctica have multiple constraints on dynamics over the past ~15,000 years (a period that spans the deglaciation of the Antarctic continental shelf since the Last Glacial Maximum). The geologic constraints include grounding-line positions, deglacial chronologies, and information on grounding line-ice shelf processes. The models will be used to investigate necessary perturbations and controls that meet the geological constraints. The multidisciplinary approach of merging geologic reconstructions of paleo-ice behavior with numerical models of ice response will allow the research team to test understanding of subglacial controls on grounding-line dynamics and assess the stability of modern grounding lines.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.