Improved models of West Antarctic glacial isostatic adjustment through new crustal motion data

本项目解决了目前南极西部冰盖对全球海平面上升的贡献的不确定性。这些估计主要来自空间大地测量（测高或时变重力）测量，而GRACE卫星任务的时变重力数据是唯一能够确定整个冰盖冰质量平衡的技术。然而，对总质量变化（由GRACE测量）进行精确校正以获得冰质量变化，由于对精确校正冰川均衡调整（GIA）缺乏信心而变得复杂。事实上，最近公布的关于南极洲西部冰质量变化的估计被目前GIA模型的不确定性所淹没。全球定位系统（GPS）时间序列为GIA提供了重要的限制，并且确实已安装在许多关键位置。然而，目前的GPS站点网络虽然允许分离非常不同的GIA模型，但过于稀疏，无法提供生产改进模型所需的严格约束/因此需要GPS站点的高空间分辨率。特别是，南极半岛南部/罗讷冰架包含一个非常大的GRACE信号，但目前的站点密度太稀疏，无法明确确定重力变化的起源。在这一地区有更多合适的露头岩石可供进一步收集数据，在那里设置新的、更密集的连续地点将提供所需的限制。在这里，我们建议通过新收集的gps数据对南极GIA模型施加改进的约束，从而使我们能够计算出新的准确和精确的冰质量对西南极洲海平面上升的贡献。

This project addresses the current uncertainty in the present-day contribution of the West Antarctic Ice Sheet to global sea level rise. These estimates are primarily derived from space geodetic (altimetry or time-variable gravity) measurements, with time-variable gravity data from the GRACE satellite mission the only technique capable of determining ice mass balance for the entire ice sheet. Accurate correction of total mass change (measured by GRACE) to obtain ice mass change is, however, complicated by a lack of confidence in accurately correcting for glacial isostatic adjustment (GIA). Indeed, recent published estimates of ice mass change for West Antarctica are swamped by the present uncertainty in GIA models. Global Positioning System (GPS) time series offer important constraints on GIA and, indeed, have been installed in many of the critical locations. However, the current network of GPS sites, whilst allowing separation of wildly different GIA models, is too sparse to provide the tight constraints required for producing improved models / for that a high spatial resolution of GPS sites is required. In particular, the southern Antarctic Peninsula/Ronne Ice Shelf contains a very large GRACE signal, but the current station density there is too sparse to unambiguously determine the origin of the gravity change. Further suitable rock outcrops are available in this region for additional data collection and situating there new, more densely spaced, continuous sites would provide the required constraints. Here, we propose to place improved constraints on an Antarctic GIA model through newly collected GPS-data, thereby allowing us to compute new accurate and precise estimates of ice mass contributions to sea level rise from West Antarctica.