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

OPP-0713970 DavisOPP-071首席调查员请求支持一项涉及遥感的跨学科高分辨率研究，并对格陵兰两个最大的出口冰川进行实地调查。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，这些冰川代表着大气、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器网络对出口冰川的第一次长期占用，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排出的冰盖对外部压力的反应方式。出口冰川流量出现显著速度变化的时间尺度似乎比以前认为的要宽得多，在10秒到几年的时间尺度上出现显著变化。对冰川地震的分析表明，在一两分钟的时间里，大量冰的移动速度可能会比它们的平均年速度快1000倍，而且在一些冰川上观察到的平均年流动速度在短短几年内就翻了一番。现在，多项观察表明，冰川流动行为可以对环境变化做出快速反应，包括快速的气候变化。然而，目前还不清楚是什么机制或机制组合允许或驱动了时间变化，也不清楚不同时间尺度上流动行为的变化如何相互关联。要了解控制从几分钟到几年的时间尺度变化的力平衡的变化，需要在空间和时间上以比目前可用的更高的分辨率进行观测，并全面了解短期和长期时间尺度过程之间的相互作用，以及外部作用力和冰川流动行为之间的相互作用，这需要整合几个传统上分开的学科的数据和专门知识。智力上的功绩。这项研究将极大地改善对排干格陵兰冰盖的大型快速出口冰川的流动动力学以及其流动速度和模式的时间变异性的理解。它将提供对冰川地震控制过程的洞察，以及冰川地震活动与全球气候变化之间可能的联系。了解对主要出口冰川流动结构的控制，以及它们可能对气候强迫作出反应的时间尺度，对于正确模拟受新鲜极地融化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反应将有助于改进耦合冰海洋大气系统的建模及其与固体地球的相互作用。根据这一建议开发的大地测量仪器和处理技术将使冰川和火山监测等各种环境中的研究人员受益，这些环境涉及快速、大规模的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 willbenefit researchers in a variety of environments such as glacier and volcano monitoring involving rapid, large-scale motions and the risk of instrument loss.