Permafrost thaw: better understanding for better management

简介：加拿大30%-50%的陆地下存在永久冻土，其中越来越多的冻土正在进入融化状态(地下冰缓慢融化)，在大多数地区将持续数十年至数百年。该计划旨在通过提供新的见解、技术、方法和HQP来加强量化正在融化的永久冻土的能力。这是及时的，因为温度本身并不适合在一个以实际或即将融化为主导的环境中为决策和研究提供信息。温度是当今测量和描述永久冻土状态的主要参数。*预期结果：该计划将产生一类新的测量方法，通过观察地下冰和水含量的变化，以及将大气和地面的变化与永久冻土融化联系起来的下一代计算机模拟工具和方法，来量化永久冻土融化。预计这些能力将更好地洞察永久冻土融化过程及其在空间和时间上的自然变异性，并直接转化为应用。*方法：该程序是围绕计算机模拟和多年冻土融化的现场测量的联合解释而建立的。为了提供相关比例尺上相关变量的数据，正在调整和发展一些测量方法。一个原型传感器被用来根据现场测量的介电特性来量化地下的冰和液态水含量。重复的地面激光扫描被用来为102到103平方米的区域提供精确的表面积分，其差异被解释为冰的损失。对于这些地区，地表和地下物质以及地形和植被的非均质性也在野外被量化，以便进行参数化模拟。温度和冰含量的变化是基于将大气再分析与地面测量联系起来的模拟框架来计算的。*意义：通过阐明地下冰和水的动力学，该项目将为永久冻土科学做出关键贡献。在对其对陆地生态系统、工程和气候变化影响的快速增长的研究中，对融化的更严格和更正式的量化将具有广泛的意义。该计划还有助于改进对快速环境变化的管理：根据工程或环境变化建立情景并区分可能和不可能的未来状态的能力(技术和HQP形式)。潜在用户包括设计、建造或运营基础设施的行业，以及运营基础设施或关注永久冻土地区的自然保护和环境监测的政府机构。

INTRODUCTION: Permafrost is present beneath 30-50% of Canada's land area and more and more of this is entering a state of thaw (slow loss of subsurface ice) that in most parts will persist for decades to centuries. This program aims to strengthen the ability to quantify thawing permafrost by providing new insight, technology, methods, and HQP. This is timely because temperature, the main quantity used for measuring and describing the state of permafrost today, is by itself not well suited to inform decisions and research in an environment dominated by actual or impending thaw.***EXPECTED RESULTS: This program will result in a new class of measurements to quantify permafrost thaw by observing changes in the subsurface contents of ice and water as well as next generation computer simulation tools and methods linking changes in the atmosphere and at the ground surface with permafrost thaw. These capabilities are expected to provide better insight into the processes of permafrost thaw and their natural variability in space and time and to directly translate to application. ******METHODS: The program is built around the joint interpretation of computer simulations and field measurements of permafrost thaw. To provide data of relevant variables at relevant scales, a number of measurement methods are being adapted and developed. A prototype sensor is used to quantify ice and liquid water contents in the ground based on measuring in situ dielectric characteristics. Repeated terrestrial laser scanning is used to provide accurate surface integrals for areas of 102 to 103 m2, the difference of which is interpreted in terms of ice loss. For these areas, also the heterogeneity of surface and subsurface material as well as topography and vegetation are quantified in the field in order to parameterize simulations. Changes in temperature and ice content are computed based on a simulation framework linking atmospheric re-analyses with ground measurements.***SIGNIFICANCE: By elucidating subsurface ice and water dynamics this project will provide a key contribution to permafrost science. In the rapidly growing research on its effects on terrestrial ecosystems, engineering, and climate change, a more rigorous and formal quantification of thaw will be of broad significance. This program further contributes a key element to the improved management of rapid environmental change: The ability (technical and in the form of HQP) to build scenarios based on engineering or environmental change and to distinguish likely from unlikely future states. Potential users include industry that designs, builds, or operates infrastructure as well as government agencies operating infrastructure or concerned with nature protection and environmental monitoring in permafrost areas.**