Collaborative Research: A New Radiostratigraphic Database for the Greenland Ice Sheet and Critical Boundary Conditions for the Next Generation of Ice-Sheet Models

预测冰盖模型是我们理解格陵兰冰盖(GIS)上的强迫和反馈的累积影响的最佳工具。然而，这些模型缺乏关于地理信息系统基本边界条件的细节，而基本边界条件是对冰流的关键控制。它们也没有利用其内部放射性地层学中包含的丰富信息，但这可能成为它们作为预测工具进行验证和应用的关键组成部分。为了满足对冰盖模型的新限制的需要，提供了资金来开发、验证和分析地理信息系统的新的放射性地层学数据库。该数据库将来自过去(例如，PARCA、CReSIS)和正在进行的(例如，冰桥)机载雷达探测活动。研究目标有三个方面：1.开发新的自动拾层技术。在雷达数据中挑选广泛的层往往是一个耗时的过程。最近的进展使自动化分层技术得到显著改进，这将使人们对冰盖辐射地层学的性质有更深入的了解，并加快对由此产生的冰流历史的更精确研究。全新世地表与基础物质平衡的研究。拾取的放射性地层学将与应变率建模相结合，以绘制整个地理信息系统中全新世地表堆积和基础熔体速率。这一经过验证的方法将扩展到以前在格陵兰北部的应用，利用他们对过去冰流条件的了解来量化不确定性。这项研究将有助于加深对格陵兰-S冰下地质的认识，并为地理信息系统的冰流模型提供关键的边界条件。LAYERMAP：一个过时的地理信息系统放射地层学模型。放射性地层数据库将以类似于冰盖下海床高度的方式进行网格化。LAYERMAP将有助于推进政府间气候变化专门委员会级别的地理信息系统冰盖模型，其对地理信息系统未来演变的预测将取决于对其现代状态的数据验证。此外，LAYERMAP将提供一种方法来绘制整个地理信息系统的基本条件和冰川排水特征。观察表明，最近格陵兰冰盖退化对全球海平面上升的贡献正在加速。目前对海平面上升速度的预测受到很大误差范围的限制，无法准确评估减轻海平面上升影响所需的应对措施。该项目将开发验证和约束格陵兰冰盖对未来海平面贡献的模型所需的数据集。

Predictive ice-sheet models are our best tools for understanding the cumulative effects of forcings and feedbacks upon the Greenland Ice Sheet (GIS). However, these models lack detail concerning the GIS basal boundary condition, which is a critical control upon ice flow. They also do not take advantage of the wealth of information contained in its internal radiostratigraphy, but that could become a key component of their validation and application as predictive tools.To address this need for new constraints on ice-sheet models, funds are provided to develop, validate, and analyze a new radiostratigraphic database of the GIS. The database will be derived from past (e.g., PARCA, CReSIS) and ongoing (e.g., IceBridge) airborne radar-sounding campaigns. The research objectives are three-fold:1. Development of novel automated layer-picking techniques. Picking widespread layers in radar data is often a time-intensive process. Recent advances permit dramatic improvements in automated layer picking, which will yield both insights into the nature of ice-sheet radiostratigraphy and accelerate a more precise study of ice-flow history from it.2. Holocene surface and basal mass balance of the GIS. The picked radiostratigraphy will be combined with strain-rate modeling to map both Holocene surface-accumulation and basal melt rates across the GIS. This proven method will be extended beyond its previous application to northern Greenland, with uncertainties quantified using their knowledge of past ice-flow conditions. This study will both inform understanding of Greenland?s subglacial geology and provide key boundary conditions for ice-flow models of the GIS.3. LAYERMAP: A dated radiostratigraphic model of the GIS. The radiostratigraphic database will be gridded in a manner similar to that for bed elevation underneath ice sheets. LAYERMAP will contribute to the advancement of IPCC-level ice-sheet models of the GIS, whose projections of its future evolution will hinge on data validation of its modern state. In addition, LAYERMAP will provide a means of mapping basal conditions and englacial drainage features across the GIS.Observations suggest a recent acceleration of the contribution of a degrading Greenland Ice Sheet to global sea level rise. Present projections of the rate of sea level rise are bounded by broad error bars, preventing accurate assessment of the response necessary to mitigate the impact of sea level rise. This project will develop data sets needed to validate and constrain models of the Greenland Ice Sheets contribution to future sea level.