Collaborative Research: Investigating Ice Sheet - Solid Earth Feedbacks in West Antarctica: Implications for Ice Sheet Evolution and Stability

南极洲西部的地球表面正以极高的速度上升，这是对冰盖质量卸载的反应。本研究(1)利用全球定位系统（GPS）提高了地表隆起测量的空间覆盖和精度；(2)利用地震学探测了深部地球结构。这些观测结果将被整合到一个最先进的三维冰盖模型中，以模拟南极西部冰盖过去和未来的行为，并评估其脆弱性。该项目的结果将有助于评估南极西部冰盖的变化率及其加速全球海平面上升的时间框架，预计这将对美国海岸线产生更大的影响。该研究项目通过技术进步和国际伙伴关系，建立并利用了先前对自主观测基础设施的投资。该项目存档的开放获取数据将促进一系列研究，这些研究将促进对南极大陆及其冰盖覆盖的基本认识。该项目将通过实地考察、研讨会和利用在线资源库的暑期学校，培训和指导一批跨学科的极地科学家。POLENET-ANET自主GPS和地震网络将被重新配置，以获取Amundsen Embayment周围的高分辨率原位数据，以捕获冰盖快速变化区域的空间变化地壳运动和地球结构。地幔温度、黏度和岩石圈弹性厚度横向变化的模式和规模将在结合新仪器足迹的地震学研究中建立，其分辨率是表征该系统所必需的。利用高精度GPS时间序列的地壳运动数据，结合南极西部冰盖（WAIS）地表物质平衡和冰史信息，独立确定绝对地幔粘度值。在地幔粘度在短空间尺度上变化，冰盖下基岩地形复杂的地方，如对南极洲西部的假设，冰盖和固体地球之间可能会出现正反馈和负反馈，通过升高或降低接地线，减少或增加主要出口冰川下的逆行床坡来稳定或破坏冰动力学。三维地球结构的新约束将被构建到创新的三维冰川均衡调整（GIA）模型和气候-冰冻圈-固体地球系统耦合模型中。这些先进的模式在本项目获得的新观测资料的约束下，将模拟西南极洲冰原过去和未来的演变，以改进对西南极洲冰质量变化的估计，确定西南极洲冰原可能因地球持续变形而稳定的位置，并减少对未来海平面变化预估中的不确定性。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。

The earth's surface in West Antarctica is rising at extremely high rates in response to unloading of ice sheet mass. This research (1) improves the spatial coverage and accuracy of measurements of surface uplift using the Global Positioning System (GPS) and (2) probes the structure of the deep earth using seismology. These observations will be integrated into a state-of-the-art, 3-D ice sheet model to simulate the past and future behavior of the West Antarctic Ice Sheet and assess its vulnerability. Project results will allow assessment of the West Antarctic Ice Sheet's rate of change and the time frame for its accelerating contribution to global sea-level rise, which is predicted to have an amplified impact for U.S. coastlines. This research program builds on and leverages prior investments in autonomous observational infrastructure through technological advances and international partnerships. Archived open-access data from the project will facilitate a range of studies that will advance basic knowledge of the Antarctic continent and its ice sheet cover. The project will train and mentor an interdisciplinary cohort of polar scientists through field work, workshops, and a summer school leveraged by an online resource library. The POLENET-ANET autonomous GPS and seismic network will be reconfigured to acquire higher-resolution in situ data focused around the Amundsen Embayment to capture spatially varying crustal motions and Earth structure in a region where the ice sheet is rapidly changing. The pattern and scale of lateral variations in mantle temperature, viscosity, and lithospheric elastic thickness at the resolution necessary to characterize this system will be established from seismological studies incorporating the new instrumentation footprint. Absolute mantle viscosity values will be independently determined using crustal motion data from high-precision GPS time series together with West Antarctic Ice Sheet (WAIS) surface mass balance and ice history information. Where mantle viscosity varies over short spatial scales and bedrock topography below the ice sheet is complex, as is hypothesized for West Antarctica, both positive and negative feedbacks between the ice sheet and the solid earth may occur, acting to stabilize or destabilize ice dynamics by raising or lowering the grounding line and reducing or increasing retrograde bed slopes below major outlet glaciers. New constraints on 3-D Earth structure will be built into innovative 3-D glacial isostatic adjustment (GIA) models and coupled models of climate-cryosphere-solid Earth systems. These advanced models, constrained by the new observations obtained in this project, will simulate the past and future evolution of the WAIS to improve estimates of changing ice mass in West Antarctica, establish where the WAIS may be stabilized by ongoing Earth deformation, and reduce uncertainties in projections of future sea level change.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.