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首页> 外文期刊>Journal of Glaciology >Inference of accumulation-rate patterns from deep layers in glaciers and ice sheets
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Inference of accumulation-rate patterns from deep layers in glaciers and ice sheets

机译：从冰川和冰盖深层推断出堆积率模式

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摘要

The spatial pattern of accumulation rate can be inferred from internal layers in glaciers and ice sheets. Non-dimensional analysis determines where finite strain can be neglected ('shallow-layer approximation') or approximated with a local one-dimensional flow model ('local-layer approximation'), and where gradients in strain rate along particle paths must be included ('deep layers'). We develop a general geophysical inverse procedure to infer the spatial pattern of accumulation rate along a steady-state flowband, using measured topography of the ice-sheet surface, bed and a 'deep layer'. A variety of thermomechanical ice-flow models can be used in the forward problem to calculate surface topography and ice velocity, which are used to calculate particle paths and internal-layer shapes. An objective tolerance criterion prevents over-fitting the data. After making site-specific simplifications in the thermomechanical flow algorithm, we find the accumulation rate along a flowband through Taylor Mouth, a flank site on Taylor Dome, Antarctica, using a layer at approximately 100 m depth, or 20% of the ice thickness. Accumulation rate correlates with ice-surface curvature. At this site, gradients along flow paths critically impact inference of both the accumulation pattern, and the depth-age relation in a 100 m core.
机译：累积速率的空间模式可以从冰川和冰盖的内层推断出来。无量纲分析确定了可以忽略有限应变的位置（“浅层近似值”）或使用局部一维流动模型进行近似值（“局部层近似值”），以及必须包括沿粒子路径的应变率梯度的位置（“深层”）。我们使用冰盖表面，床层和“深层”的实测地形，开发了一种通用的地球物理逆过程来推断沿稳态流带的累积速率的空间格局。可以在正向问题中使用多种热机械冰流模型来计算表面形貌和冰速，以用于计算粒子路径和内层形状。客观公差标准可防止数据过度拟合。在热机械流算法中进行了特定于地点的简化后，我们使用约100 m深度或冰厚度20％的层，找到了通过泰勒口（南极泰勒圆顶（Taylor Dome）的侧翼部位）沿流带的累积速率。累积速率与冰面曲率相关。在这个位置，沿流径的梯度会严重影响堆积模式的推断以及100 m岩心中的深度-年龄关系。

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