Collaborative Research: High-resolution studies of glacier dynamics at two major outlet glaciers in East Greenland

主要研究人员请求支持一项跨学科、高分辨率的研究，该研究涉及格陵兰岛两个最大的出口冰川的遥感和实地调查。对Helheim和Kangerdlugssuaq冰川的研究将整合地震学、冰川学和大地测量学观测，以建立对主要出口冰川流动动力学的理解，这些冰川代表了大气、冰冻圈和水圈之间的关键连接点。该项目将是全球定位系统接收网络第一次长期占领一个出口冰川，并将解决地震到年际时间尺度上的流量变化问题。最近的发现清楚地表明，我们对大型出口冰川流动动力学的理解是有限的，不足以理解出口冰川及其流失的冰盖对外部强迫的反应方式。冰川出口水流可能发生显著速度变化的时间尺度范围似乎比以前认为的要宽得多，显著变化发生在几十秒到几年的时间尺度上。对冰川地震的分析表明，在一两分钟的时间内，大量的冰可能以比年平均速度快1000倍的速度移动，并且在一些冰川中，仅在几年内就观察到年平均速度增加了一倍。目前的多项观测表明，冰川流动行为可以迅速响应环境变化，包括快速的气候变化。然而，目前尚不清楚什么机制或机制组合允许或驱动时间变化，也不清楚不同时间尺度上流动行为的变化是如何相互关联的。了解控制从分钟到年的时间尺度变化的力平衡的变化，需要在空间和时间上比目前可用的更高分辨率的观测，并且实现短期和长期过程之间以及外部强迫和冰川流动行为之间相互作用的全面图景，需要整合来自几个传统上独立学科的数据和专业知识。知识价值。这项研究将大大提高人们对大型、快速移动的格陵兰冰盖出口冰川的流动动力学的理解，以及对其流动速率和模式的时间变化的理解。它将深入了解控制冰川地震的过程以及冰川地震活动与全球气候变化之间的可能联系。更广泛的影响。了解主要出水口冰川流量配置的控制，以及它们可能对气候强迫作出反应的时间尺度，对于正确模拟受极地融水向世界海洋转移影响的系统非常重要。更好地了解冰川和冰盖对气候变化的响应，将有助于改进冰-海洋-大气耦合系统的建模及其与固体地球的相互作用。根据该提案开发的大地测量仪器和处理技术将使研究人员在各种环境中受益，例如冰川和火山监测，涉及快速，大规模运动和仪器丢失的风险。

ABSTRACT NettlesOPP-0713970DavisOPP-071The Principal Investigators request support for an interdisciplinary, high-resolution study involving remote sensing and field investigations at two of Greenland's largest outlet glaciers. The study of the Helheim and Kangerdlugssuaq Glaciers will integrate seismological, glaciological, and geodetic observations to build an understanding of flow dynamics at major outlet glaciers, which represent a critical junction between the atmosphere, cryosphere, and hydrosphere. The project would be the first long-term occupation of an outlet glacier by a GPS receiver network, and would address questions of flow variation on earthquake to interannual time scales. Recent discoveries have made it clear that our understanding of the dynamics of flow at large outlet glaciers is limited and inadequate for understanding the ways in which the outlet glaciers, and the ice sheets they drain, respond to external forcings. The spectrum of timescales over which significant velocity variations in outlet glacier flow can occur appears to be much broader than previously believed, with significant variations occurring on timescales of 10s of seconds to several years. Analysis of glacial earthquakes suggests that significant volumes of ice may move at speeds 1000 times faster than their average annual velocities for periods of a minute or two and a doubling of average annual flow speeds over only a few years has been observed at some glaciers. Multiple observations now indicate that glacier flow behavior can respond quickly to environmental changes, including rapid climate change. It is not currently clear, however, what mechanisms or combination of mechanisms allow for, or drive, the temporal variations, nor is it clear how variations in flow behavior at different timescales are related to one another. Understanding the changes in force balance that control variations across the range of timescales from minutes to years requires observations at higher resolution in both space and time than are currently available, and achieving a comprehensive picture of the interactions between short- and long-timescale processes, and between external forcings and glacier flow behavior, requires the integration of data and expertise from several traditionally separate disciplines.. Intellectual Merit. The research will lead to a greatly improved understanding of the dynamics of flow at the large, fast-moving outlet glaciers that drain the Greenland ice sheet and of the temporal variability in their rates and modes of flow. It will provide insight into the processes controlling glacial earthquakes and possible connections between glacial-earthquake activity and global climate change.Broader Impacts. Understanding the controls on flow configuration at major outlet glaciers, and the timescales over which they may respond to climatic forcing, is of great importance for proper modeling of systems affected by the transfer of fresh polar meltwater to the world's oceans. A better understanding of glacier and ice-sheet response to climate change will allow for improvements in modeling of the coupled ice ocean atmosphere system, and of its interactions with the solid Earth. The geodetic instrumentation and processing techniques developed under this proposal will benefit researchers in a variety of environments such as glacier and volcano monitoring involving rapid, large-scale motions and the risk of instrument loss.