Borehole climatology: contributions to the understanding of climate change

井眼温度剖面（BTPs）数据是我们了解百年温度变化的重要信息来源之一。基于BTPs的气候重建假设地表空气温度变化与地表温度变化耦合，并通过热传导传播到地下。换句话说，如果我们假设地球上地壳处于热平衡状态，那么上面几公里的温度分布是由长期（100- 1000年）的地表温度和内部热流（100-105年不变）决定的。在这些条件下，对于已知的岩石热性质，温度随深度线性增加。如果地球表面的温度发生变化，那么地面就会获得或失去一定数量的热量；地表能量平衡的这些变化在地下传播并被记录为平衡热状态的扰动。气候扰动的向下传播取决于岩石的热扩散率（约10(-6)m2/s），因此表面地壳的前几百米储存了上一千年的综合热特征。由于热传导的性质，表面扰动的振幅呈指数衰减，并且它们的相移随深度作为它们的时间尺度的函数。该过程作为低通滤波器工作，使得低频变化比高频变化传播得更深。通常情况下，扰动每年穿透约20米，100年穿透150米，一千年穿透约500米，因此地表最近的能量平衡变化仍然记录在浅层地下。对这些地下扰动的分析为钻孔法检索地表过去的温度变化提供了基础。该提案涉及该学科面临的最重要问题，并提出了解决这些问题的方法，同时将通过对这些关键领域的研究培养未来的科学家。

Data from borehole temperature profiles (BTPs) have been one source of information that has significantly contributed to our understanding of centennial temperature changes. Climate reconstructions based on BTPs assume that surface air temperature changes are coupled to ground surface temperature changes and propagate to the subsurface by thermal conduction. In other words, if we assume the Earth's upper crust is at thermal equilibrium, then the temperature distribution in the upper few kilometers is determined by the long-term (>1000 years) surface temperature and the internal heat flow (constant at the 100-105 year scale). Under these conditions, for known thermal properties of the rocks, the temperature increases linearly with depth. If the temperature at the Earth's surface changes, then a quantity of heat will be gained or lost by the ground; these changes in the energy balance at the surface propagate and are recorded underground as perturbations to the equilibrium thermal regime. The downward propagation of the climate disturbance depends on the thermal diffusivity of the rock (ca. 10(-6) m2/s) so that the first few hundred meters of the surface crust store the integrated thermal signature of the last millennium. Due to the nature of heat conduction the amplitude of surface disturbances is exponentially attenuated and their phase shifted with depth as a function of their time scales. The process operates as a low pass filter such that the low-frequency variations propagate deeper than those with higher frequency. Typically, perturbations penetrate about 20 m in a year, 150 m in 100 years and about 500 m in a millennium, such that recent energy balance changes at the surface remain recorded in the shallow subsurface. Analysis of these underground perturbations provides the base of the borehole approach to retrieve past temperature changes at the ground surface. This proposal deals with the most important issues facing this discipline and proposes to find solutions to this issues and at the same time will train future scientists through research on these key areas of borehole climatology.