Interpretation of Arctic North Slope Permafrost Borehole Thermal Evolution in Light of Spatial and Temporal Variation in Surface Temperature Fields

基于地表温度场时空变化的北极北坡多年冻土钻孔热演化解释

• 批准号: 1203945
• 负责人: Robert Anderson
• 金额: $ 9.14万
• 依托单位: University of Colorado at Boulder
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-08-15 至 2015-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1203945&HistoricalAwards=false
• 关键词: Interpretation; Arctic; North; Slope; Permafrost

Permafrost is ground that has remained below 0°C for more than two years. It has the greatest areal extent of any component of the cryosphere in the Northern Hemisphere. Feedbacks between permafrost, the hydrologic cycle, and the atmosphere are key components of the Arctic system. As the health of permafrost is directly dependent upon temperature, the thermal state of permafrost is one of the key signals of climate change. In addition, the thickness, distribution and temperature of permafrost influences both ecology and engineering in the Arctic. Between the atmosphere and the top of the permafrost is the active layer, which freezes and thaws on an annual basis. This active layer translates the climate signal at the Earth?s surface into heat flow into or out of the underlying conductive permafrost. The heat flux at the base of the active layer can be determined from profiles of temperature within the active layer, based on well-known physics of conduction. The goal in this project is to identify both spatial and temporal patterns of change in the permafrost of Alaska?s Arctic North Slope, and the critical processes that govern these patterns. Temperature profiles documented in the 1970s from abandoned exploratory boreholes suggested that the permafrost had warmed significantly to depths of many tens of meters, in a pattern that could be best explained by a 2-4°C surface warming over the prior half century. Since then, an array of 21 boreholes, spanning the National Petroleum Reserve-Alaska (NPR-A), has been repeatedly re-logged by USGS researchers, providing a record of dramatic change. The simplest interpretation of these profiles suggests yet more rapid increases in surface temperature, with a change of 3°C/decade occurring in the 1990s. The surface meteorology and active layer thermal structure has simultaneously been documented in an array of automated surface stations that span the region, and have been maintained for periods ranging from one to two decades. Nine of these surface stations are co-located with deep boreholes; all are embedded in international efforts to monitor the thermal state of the globe?s permafrost. The USGS network represents both the largest array of deep boreholes in the world used for monitoring the thermal state of the permafrost, and the densest array of surface stations in the global network.The investigators will integrate the observations of temperature profiles collected periodically from the deep boreholes, and 1-2 hourly observations of near surface meteorology and near surface soil temperature, to constrain the spatial and temporal record of the energy going into the permafrost. It will also extract the cleanest climate signal possible from the borehole measurements over the measurement interval (1970s onward) with the aim of answering questions about the thermal state of the landscape and the processes responsible for its evolution. To accomplish these goals the PI will first work with USGS colleagues to finalize quality control of their observations (preliminary data available at: http://data.usgs.gov/climateMonitoring/region/ show?region=alaska). He will then develop numerical models that predict the thermal disturbance from site-specific effects (e.g., length of time drilling, presence of lakes). Finally, using the ?cleanest? climate signal of warming and heat flow into the permafrost, the team will analyze the spatial and temporal pattern of this signal.Results will be available through both the scientific literature, and the Community Surface Dynamics Modeling System (CSDMS, http://csdms.colorado.edu/wiki/Main_Page) Educational repository. We will develop interactive models, animations, and classroom exercises based on this dataset, modeling effort, and final analysis.

多年冻土是在0°C以下的地面，持续了两年多。它具有北半球冰冻圈任何成分的最大面积。多年冻土，水文循环和大气之间的反馈是北极系统的关键组成部分。由于多年冻土的健康直接取决于温度，因此多年冻土的热状态是气候变化的关键信号之一。另外，多年冻土的厚度，分布和温度会影响北极的生态学和工程。在大气和永久冻土顶部之间是活性层，该层每年冻结和融化。该活性层将地球表面的气候信号转化为热流入或从下面的导电性永久冻土中。基于该项目的目标的众所周知的物理学，可以从活性层内的温度曲线确定活性层的热通量是确定阿拉斯加北极北斜率多年冻土的空间和临时变化模式，以及控制这些模式的关键过程。 1970年代记录在1970年代的温度剖面，从废弃的探险家钻孔中表明，永久冻土已经显着温暖到许多数十米的深度，这种模式可以通过在过去半个世纪的2-4°C表面变暖来最好地解释。从那时起，跨越全国石油储备 - 阿拉斯加（NPR-A）的21个钻孔已被USGS研究人员反复重新播放，提供了巨大变化的记录。对这些轮廓的最简单解释表明，表面温度的迅速升高，在1990年代发生了3°C/十年。表面气象和活动层热结构已在跨该区域的一系列自动化表面站中进行了记录，并且已经维持了一到二十年。这些水面站中的九个是用深井孔共同置于的。所有这些都嵌入了国际努力中，以监测全球冻土的热状态。 The USGS network represents both the largest array of deep boreholes in the world used for monitoring the thermal state of the permafrost, and the densest array of surface stations in the global network.The Investigators will integrate the observations of temperature profiles collected periodically from the deep boreholes, and 1-2 hourly observations of near surface meteorology and near surface soil temperature, to constrain the spatial and temporary record of the energy going into the多年冻土。它还将从测量间隔（1970年代）的钻孔测量中提取最清洁的气候信号，目的是回答有关景观热状态及其进化过程的过程的问题。为了实现这些目标，PI将首先与USGS同事合作，以最终确定其观察值的质量控制（初步数据可获得：http：//data.usgs.gov/climatemonitoring/region/ show show？region = alaska）。然后，他将开发数值模型，这些模型可以从特定地点效应（例如，时间钻孔，湖泊的存在）来预测热灾难。最后，使用“最清洁？攀爬的热量和热量流入永久冻土的信号，团队将分析此信号的空间和临时模式。星期将通过科学文献和社区表面动态建模系统（CSDMS，http://csdms.colorado.edu/wiki/main_page）提供。我们将根据此数据集，建模工作和最终分析开发交互式模型，动画和课堂练习。