In this study, we explore small-scale (~1 to 20 km) thermal-refractive effects on basal geothermal heat flux (BGHF) at subglacial boundaries resulting from lateral thermal conductivity contrasts associated with subglacial topography and geologic contacts. We construct a series of two-dimensional, conductive, steady-state models that exclude many of the complexities of ice sheets in order to demonstrate the effect of thermal refraction. We show that heat can preferentially flow into or around a subglacial valley depending on the thermal conductivity contrast with underlying bedrock, with anomalies of local BGHF at the ice–bedrock interface between 80 and 120% of regional BGHF and temperature anomalies on the order of ±15% for the typical range of bedrock conductivities. In the absence of bed topography, subglacial contacts can produce significant heat flux and temperature anomalies that are locally extensive (>10 km). Thermal refraction can result in either an increase or decrease in the likelihood of melting and ice-sheet stability depending on the conductivity contrast and bed topography. While our models exclude many of the physical complexities of ice behavior, they illustrate the need to include refractive effects created by realistic geology into future glacial models to improve the prediction of subglacial melting and ice viscosity.

中文翻译：

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热折射：对冰下热通量的影响

在这项研究中，我们探索了与冰下地形和地质接触相关的横向热导率对比导致的冰下边界处基础地热热通量 (BGHF) 的小尺度（~1 至 20 公里）热折射效应。我们构建了一系列二维、传导、稳态模型，排除了冰盖的许多复杂性，以证明热折射的影响。我们表明，热量可以优先流入或绕过冰下山谷，这取决于与下伏基岩的热导率对比，冰-基岩界面的局部 BGHF 异常在区域 BGHF 的 80% 和 120% 之间，温度异常约为 ±对于典型的基岩电导率范围，为 15%。在没有床位地形的情况下，冰下接触会产生显着的热通量和局部广泛（> 10 km）的温度异常。取决于电导率对比和床层地形，热折射可以导致融化和冰盖稳定性的可能性增加或减少。虽然我们的模型排除了冰行为的许多物理复杂性，但它们说明了将现实地质产生的折射效应纳入未来冰川模型的必要性，以改进对冰下融化和冰粘度的预测。