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

目前南极洲冰块质量的减少在很大程度上是由冰川接地线的变化推动的，在那里内陆冰从搁浅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。该项目将过去冰川退缩事件的证据和其他现场数据，如接地线的位置和日期、冰川下地形和融水特征，纳入到冰流的数值模型中，以调查过去15,000年来接地线过程和冰川下地形对冰川退缩速度的影响。最近的观测表明，南极冰块的质量损失主要是由接地线或附近的扰动驱动的。然而，缺乏关于冰下和接地线环境的信息，导致对质量损失和海平面上升的预测存在很大的不确定性。该项目将把冰川消融大陆架的地质数据整合到从一维到三维的不同复杂程度的数值模型中。南极冰盖数值模型很少对过去15,000年(自上次冰盛期以来南极大陆架消融)的动力学有多重限制。地质约束包括接地线位置、冰川消融年代学和关于接地线-冰架过程的信息。这些模型将被用来调查满足地质约束的必要扰动和控制。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团队能够测试对冰下控制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，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

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.