Implications of high-resolution velocity and strain rate observations for modelling of Greenlandic tidewater glaciers

IF 2.8 3区 地球科学 Q2 GEOGRAPHY, PHYSICAL
Dominik Fahrner, Pablo J. González, Douglas W. F. Mair, James M. Lea
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引用次数: 0

Abstract

Synthetic Aperture Radar (SAR) has been used extensively to determine the surface ice flow velocity of tidewater glaciers and investigate changes in seasonal or annual ice dynamics at medium spatial resolution (⩾100 m). However, assessing tidewater glacier behaviour at these resolutions risks missing key details of glacier dynamics, which is particularly important for determination of strain rates that relate to crevasse formation, depth, and ice damage. Here we present surface ice velocity and strain maps with a 16 m posting derived from high-resolution (1 m) PAZ Ciencia spotlight mode SAR imagery for Narsap Sermia, SW Greenland, for October 2019 to February 2021. Results reveal fine details in strain rate, including an area of compression proximal to the terminus, with an upstream shift of strains through time. The velocity evolution of Narsap Sermia shows distinct seasonal changes starting in summer 2020, which are largely modulated by the subglacial drainage system. Comparison of our results with medium-resolution velocity products shows that while these can capture general strain and velocity patterns, our high-resolution data reveals considerably larger ranges of strain values. This is likely to have implications for tuning strain rate dependent calving and ice damage parameterisations within numerical models.

高分辨率速度和应变率观测对格陵兰潮水冰川建模的影响
合成孔径雷达(SAR)已被广泛用于确定潮水冰川的表面冰流速度,以及研究中等空间分辨率(⩾100 米)的季节或年度冰动力学变化。然而,在这些分辨率下评估潮水冰川行为可能会遗漏冰川动力学的关键细节,这对于确定与裂缝形成、深度和冰损害有关的应变率尤为重要。在此,我们展示了格陵兰西南部纳尔萨普-塞米亚在 2019 年 10 月至 2021 年 2 月期间的高分辨率(1 米)PAZ Ciencia 聚光模式合成孔径雷达图像中得出的 16 米张贴表面冰速和应变图。研究结果揭示了应变率的细节,包括在终点附近的压缩区域,应变随时间向上游移动。从 2020 年夏季开始,Narsap Sermia 的速度演变显示出明显的季节性变化,这在很大程度上受到冰川下排水系统的调节。将我们的结果与中等分辨率的速度产品进行比较后发现,虽然这些产品可以捕捉到一般的应变和速度模式,但我们的高分辨率数据揭示出的应变值范围要大得多。这可能会对调整数值模型中与应变率相关的压裂和冰损害参数产生影响。
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来源期刊
Journal of Glaciology
Journal of Glaciology 地学-地球科学综合
CiteScore
5.80
自引率
14.70%
发文量
101
审稿时长
6 months
期刊介绍: Journal of Glaciology publishes original scientific articles and letters in any aspect of glaciology- the study of ice. Studies of natural, artificial, and extraterrestrial ice and snow, as well as interactions between ice, snow and the atmospheric, oceanic and subglacial environment are all eligible. They may be based on field work, remote sensing, laboratory investigations, theoretical analysis or numerical modelling, or may report on newly developed glaciological instruments. Subjects covered recently in the Journal have included palaeoclimatology and the chemistry of the atmosphere as revealed in ice cores; theoretical and applied physics and chemistry of ice; the dynamics of glaciers and ice sheets, and changes in their extent and mass under climatic forcing; glacier energy balances at all scales; glacial landforms, and glaciers as geomorphic agents; snow science in all its aspects; ice as a host for surface and subglacial ecosystems; sea ice, icebergs and lake ice; and avalanche dynamics and other glacial hazards to human activity. Studies of permafrost and of ice in the Earth’s atmosphere are also within the domain of the Journal, as are interdisciplinary applications to engineering, biological, and social sciences, and studies in the history of glaciology.
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