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在以极高的速度上升，以回应冰盖质量的卸荷。这项研究(1)提高了利用全球定位系统(GPS)测量地表隆起的空间覆盖率和精度；(2)利用地震学探索了地球深部的结构。这些观测将被整合到最先进的3-D冰盖模型中，以模拟西南极冰盖过去和未来的行为，并评估其脆弱性。项目成果将有助于评估西南极冰盖的变化速度，以及其对全球海平面上升的加速贡献的时间框架，预计这将对美国海岸线产生放大的影响。这一研究计划建立在自主观测基础设施的先前投资的基础上，并通过技术进步和国际合作伙伴关系加以利用。该项目存档的开放获取数据将促进一系列研究，促进对南极大陆及其冰盖的基本知识。该项目将通过实地工作、讲习班和在线资源库利用的暑期学校，培训和指导一批跨学科的极地科学家。POLENET-ANET自主GPS和地震网络将重新配置，以获取围绕阿蒙森湾的更高分辨率的现场数据，以捕获冰盖迅速变化的地区在空间上变化的地壳运动和地球结构。地幔温度、粘度和岩石圈弹性厚度横向变化的模式和尺度将通过纳入新仪器足迹的地震学研究来确定，这是描述该系统所需的分辨率。利用来自高精度GPS时间序列的地壳运动数据，结合西南极冰盖(WAIS)表面物质平衡和冰历史信息，将独立确定地幔绝对粘性值。在地幔粘度在短空间尺度上变化的情况下，如果冰盖下的基岩地形复杂，如西南极假设的那样，冰盖和固体地球之间可能会发生正反馈和负反馈，通过升高或降低接地线以及减少或增加主要出口冰川下方的逆行床坡来稳定或破坏冰的动力学。对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-固体地球系统的耦合模型中。这些先进的模型，受本项目中获得的新观测结果的限制，将模拟WAIS过去和未来的演变，以改进对南极洲西部冰块变化的估计，确定WAIS可能会因持续的地球变形而稳定在哪里，并减少未来海平面变化预测的不确定性。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。

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.