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

合作研究：格陵兰冰盖的新放射地层数据库和下一代冰盖模型的关键边界条件

• 批准号: 1243584
• 负责人: Mark Fahnestock
• 金额: $ 11.29万
• 依托单位: University of Alaska Fairbanks Campus
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-02-01 至 2014-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1243584&HistoricalAwards=false
• 关键词: Collaborative; Research; New; Radiostratigraphic; Database

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.

冰盖预测模型是我们了解格陵兰冰盖 (GIS) 的强迫和反馈累积效应的最佳工具。然而，这些模型缺乏有关 GIS 基本边界条件的详细信息，而 GIS 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地层学中包含的丰富信息，但这可能成为其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新限制的需求，提供了资金开发、验证和分析新的 GIS 放射地层数据库。该数据库将源自过去（例如，PARCA、CReSIS）和正在进行的（例如，IceBridge）机载雷达探测活动。研究目标有三个： 1．开发新颖的自动层拾取技术。在雷达数据中选取广泛的图层通常是一个耗时的过程。最近的进展使得自动层拾取有了显着的改进，这将产生对冰盖放射地层学性质的深入了解，并加速对冰流历史的更精确的研究。2。 GIS 的全新世表面和基底质量平衡。所选择的放射地层学将与应变率建模相结合，以绘制整个 GIS 中的全新世表面累积率和基底融化率。这种经过验证的方法将扩展到格陵兰岛北部的先前应用之外，并利用他们对过去冰流状况的了解来量化不确定性。这项研究将有助于了解格陵兰岛的冰下地质，并为 GIS.3 的冰流模型提供关键边界条件。 LAYERMAP：GIS 的过时的放射地层模型。放射地层数据库将以类似于冰盖下床高程的方式进行网格化。 LAYERMAP 将有助于改进 GIS 的 IPCC 级冰盖模型，其未来演变的预测将取决于其现代状态的数据验证。此外，LAYERMAP 将提供一种绘制整个 GIS 基础条件和冰川排水特征的方法。观察表明，最近格陵兰冰盖退化对全球海平面上升的贡献加速。 目前对海平面上升速度的预测受到广泛误差线的限制，无法准确评估减轻海平面上升影响所需的响应。 该项目将开发验证和约束格陵兰冰盖对未来海平面影响的模型所需的数据集。