论文标题
冰川上的污垢锥如何形成：现场观察，实验室实验和建模
How dirt cones form on glaciers: field observation, laboratory experiments and modeling
论文作者
论文摘要
泥锥是在冰川表面遇到的仪表结构，由冰锥组成，冰锥被薄薄的灰烬，沙子或砾石覆盖，并且是从初始碎片斑块中自然形成的。在本文中，我们报告了法国阿尔卑斯山中锥体形成的现场观察结果，实验室规模的实验在受控环境中重现了这些结构，以及二维离散元素 - 方法 - 元素 - 元素 - 元素 - 元素 - 元素 - 元素 - 元素数值模拟，耦合谷物力学和热效应。我们表明，锥形形成起源于颗粒层的绝缘特性，与裸露的冰融化相比，它减少了下面的冰融化。这种差分消融使冰表面变形并诱导晶粒的准静态流，从而导致圆锥形形状，因为与结构尺寸相比，热长度变小。圆锥体生长，直到达到稳态，在这种稳态中，污垢提供的绝缘层准确补偿了来自结构外表面增加的热通量。这些结果使我们能够确定发挥作用的关键物理机制，并开发一个能够定量重现各种现场观测和实验发现的模型。
Dirt cones are meter-scale structures encountered at the surface of glaciers, which consist of ice cones covered by a thin layer of ashes, sand or gravel, and which form naturally from an initial patch of debris. In this article, we report field observations of cone formation in the French Alps, laboratory-scale experiments reproducing these structures in a controlled environment, and two-dimensional discrete-element-method-finite-element-method numerical simulations coupling the grains mechanics and thermal effects. We show that cone formation originates from the insulating properties of the granular layer, which reduces ice melting underneath as compared to bare ice melting. This differential ablation deforms the ice surface and induces a quasi static flow of grains that leads to a conic shape, as the thermal length become small compared to the structure size. The cone grows until it reaches a steady state in which the insulation provided by the dirt layer exactly compensates for the heat flux coming from the increased external surface of the structure. These results allowed us to identify the key physical mechanisms at play and to develop a model able to quantitatively reproduce the various field observations and experimental findings.
