Borehole Climatology: Continental Energy and Climate Change

我们目睹了越来越多的关于气候系统的研究，这些研究是由对地球变暖预测的担忧所激发的。然而，确定气候模式的预估需要用过去的气候来验证它们。只有正确地模拟古气候，一个模型才能激发人们对其预测的信心。在这方面，地下温度数据对我们了解上个千年的气候做出了重大贡献。基于这些数据的气候重建假设地表气温与地表温度耦合，地表温度通过叠加在背景稳态地热场上的热扩散传播到地下。也就是说，如果地球表面的温度发生变化，那么地面就会获得一定数量的热量（变暖）或损失一定数量的热量（冷却）；地表能量平衡的这些变化作为背景热状态的扰动传播并记录在地下。这些地下异常的分析为古气候重建的地热方法提供了依据。钻孔气候学的气候重建是独一无二的；他们的推断是对长期气候的衡量，独立于气象记录。这一领域的研究在过去几年一直是我工作的重点，因为它有很大的潜力来阐明对自然状态下气候变化的理解。我提出的研究计划的结果将使我们对大气-地面界面的传热机制有更全面的了解。我的长期目标是描述从大气边界层到地壳前几百米的热传递状态。这种特征对于纳入气候模式来研究气候系统是非常有用的；特别是对于了解永久冻土的演变。来自地下的热数据是理解地球表面能量平衡的基础，也为气候模型提供了地表的长期边界条件。研究生将对最新版本的社区土地模型CLM4进行调整，以扩展其底部边界位置，以便利用地下温度来了解地表能量平衡的变化，从而了解在世纪和千年时间尺度上空气-地面界面的能量分配。我们打算对一个具有完全耦合大陆分量的全球气候模式进行千年尺度的集合模拟。为了使用大陆蓄热量作为陆地表面模型性能的衡量标准，我们将继续从世界上代表性不足的大陆地区收集额外的地热数据；例如，智利、阿根廷和巴西。我计划继续让博士和硕士学生参与到这个项目的各个方面。

We are witnesses to increased research about the climate system stimulated by concerns about projections of a warmer Earth. However, ascertaining climate models' projections requires that they be validated with the climate of the past. Only by properly simulating paleoclimate, will a model inspire confidence in its projections. In this avenue, underground temperature data have contributed significantly to our understanding of the climate of the last millennium. Climate reconstructions from these data assume that surface air temperatures are coupled to ground surface temperatures, and the latter propagate to the subsurface by thermal diffusion superimposing on the background steady-state geothermal field. That is, if the temperature at the Earth's surface changes, then a quantity of heat will be gained (warming) or lost (cooling) by the ground; these changes in the energy balance at the surface propagate and are recorded underground as perturbations to the background thermal regime. Analysis of these underground anomalies provides the base of the geothermal method of paleoclimate reconstruction. Climate reconstructions from borehole climatology are unique; their inferences are a measure of long-term climate, independent from meteorological records. This area of research has been the focus of my work for the last few years because of the great potential to shed light on the understanding of climatic change in its natural state. Results from the research program I propose will allow a more complete understanding of the heat transfer regime at the atmosphere-ground interface. My long-term objectives are to characterize the heat transfer regime from the atmospheric boundary layer to the first few hundred meters of the Earth's crust. Such characterization would be very useful for incorporation into climate models to study the climate system; in particular, to understanding the evolution of permafrost. Thermal data from the subsurface are fundamental to understanding the energy balance at the Earth's surface and also provide long-term boundary conditions at the ground surface for climate models. Graduate students will work on adapting the latest version of the Community Land Model - CLM4, to extend its bottom boundary placement to allow the use underground temperatures to understand the changes in the ground surface energy balance and thus the energy partition at the air-ground interface at century and millennia time scales. We intent to perform a millennium-scale ensemble simulation of a global climate model with a fully coupled continental component. In order to use the continental heat storage as a measure of performance of land surface models, we will continue gathering additional geothermal data from underrepresented continental areas of the world; for example, Chile, Argentina and Brazil. I plan to continue involving PhD and MSc students throughout all aspects of this project.