A general theory of glacier surges
A general theory of glacier surges
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DOI：
10.1017/jog.2019.62
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发表时间：
2019-10-01
影响因子：
3.4
通讯作者：
Sevestre, H.
中科院分区：
文献类型：
--
作者：
Benn, D., I;Fowler, A. C.;Sevestre, H.
我们提出了第一个冰川涌动的一般理论，其中包括基于耦合质量和焓预算的温带和多热冰川涌动。焓（以热能和水的形式）是在冰川床上通过地热加热加上冰流产生的摩擦加热（势能消耗）获得的。系统中融水的传导和损失会导致焓损失。由于焓直接影响流速，因此如果冰川要保持稳定的流量，质量和焓预算必须同时平衡。如果不是，冰川会经历异相质量和焓循环，表现为静止和激增阶段。我们使用集总元模型来说明该理论，该模型参数化了关键的热力学和水文过程，包括地表排水以及分布式和渠道化排水系统。模型输出展示了多温带和温带冰川涌动的许多观察到的特征，包括涌动行为与气候（降水、温度）、几何形状（长度、坡度）和床特性（水力传导率）的特定组合的关联。焓平衡理论解释了在单一框架中观察到的广泛的涌动行为，并为为什么大多数冰川不涌动这一更广泛的问题提供了答案。
We present the first general theory of glacier surging that includes both temperate and polythermal glacier surges, based on coupled mass and enthalpy budgets. Enthalpy (in the form of thermal energy and water) is gained at the glacier bed from geothermal heating plus frictional heating (expenditure of potential energy) as a consequence of ice flow. Enthalpy losses occur by conduction and loss of meltwater from the system. Because enthalpy directly impacts flow speeds, mass and enthalpy budgets must simultaneously balance if a glacier is to maintain a steady flow. If not, glaciers undergo out-of-phase mass and enthalpy cycles, manifest as quiescent and surge phases. We illustrate the theory using a lumped element model, which parameterizes key thermodynamic and hydrological processes, including surface-to-bed drainage and distributed and channelized drainage systems. Model output exhibits many of the observed characteristics of polythermal and temperate glacier surges, including the association of surging behaviour with particular combinations of climate (precipitation, temperature), geometry (length, slope) and bed properties (hydraulic conductivity). Enthalpy balance theory explains a broad spectrum of observed surging behaviour in a single framework, and offers an answer to the wider question of why the majority of glaciers do not surge.