Dynamic time warping to quantify age distortion in firn cores impacted by melt processes

IF 2.5 4区 地球科学 Q2 GEOGRAPHY, PHYSICAL
Cedric J. Hagen, J. Harper
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引用次数: 0

Abstract

As warming intensifies across the Greenland ice sheet, an increasing number of shallow coring and radar studies are targeting the melt-impacted firn column to investigate meltwater processes. Highly inhomogeneous infiltration and refreezing, however, redistributes mass, distorting age–depth relationships and confounding comparisons between different cores. Here, we utilize a dynamic time warping algorithm for time series alignment to investigate and quantify the heterogeneous impact of melt processes on nine closely spaced (within 50 m) firn core-density profiles. The 10 m cores were collected relatively high in Greenland's percolation zone, where melt alteration is minimal compared to lower elevation. Our analysis demonstrates the effectiveness of dynamic time warping as a tool for assessing heterogeneity between ice core records. We find that the optimal alignment of density profiles in the nine cores requires vertical stretching and compression of individual profiles, ranging from, on average, <1 to ~16% of the core lengths. We identified four depth zones of mass redistribution that appear to coincide with observed ice layers. Further, ~75% of density measurements from each core do not align with an age model-derived density profile that assumes no mass redistribution of meltwater, indicating the pervasive impact of melt processes.
动态时间翘曲量化受熔体过程影响的岩芯年龄扭曲
随着格陵兰冰盖变暖的加剧,越来越多的浅层取芯和雷达研究正以融化影响的冷杉柱为目标,研究融水过程。然而,高度不均匀的渗透和再冻结会重新分布质量,扭曲年龄-深度关系,混淆不同岩芯之间的比较。在这里,我们利用用于时间序列比对的动态时间扭曲算法来研究和量化熔体过程对九个紧密间隔(50米以内)的堆芯密度分布的不均匀影响。10米岩芯是在格陵兰岛渗流带相对较高的地方采集的,与较低的海拔相比,那里的熔体蚀变最小。我们的分析证明了动态时间扭曲作为评估冰芯记录之间异质性的工具的有效性。我们发现,九个岩芯中密度剖面的最佳排列需要对单个剖面进行垂直拉伸和压缩,平均范围为岩芯长度的<1%至~16%。我们确定了四个质量重新分布的深度区域,这些区域似乎与观测到的冰层一致。此外,每个岩心约75%的密度测量值与年龄模型推导的密度分布图不一致,该密度分布图假设融水没有质量再分配,这表明熔体过程的普遍影响。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
Annals of Glaciology
Annals of Glaciology GEOGRAPHY, PHYSICAL-GEOSCIENCES, MULTIDISCIPLINARY
CiteScore
8.20
自引率
0.00%
发文量
0
审稿时长
>12 weeks
期刊介绍: Annals of Glaciology publishes original scientific articles and letters in selected aspects of glaciology-the study of ice. Each issue of the Annals is thematic, focussing on a specific subject. The Council of the International Glaciological Society welcomes proposals for thematic issues from the glaciological community. Once a theme is approved, the Council appoints an Associate Chief Editor and a team of Scientific Editors to handle the submission, peer review and publication of papers.
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