Methane fluxes and isotopic composition over heterogeneous landscapes of Arctic permafrost and Siberian peatlands (MICHAEL)

北极永久冻土和西伯利亚泥炭地异质景观的甲烷通量和同位素组成（MICHAEL）

• 批准号: 465048505
• 负责人: Professorin Dr. Astrid Lampert
• 金额: --
• 依托单位: Institut für Flugführung
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/465048505?language=en
• 关键词: Methane; fluxes; isotopic; composition; over

Arctic permafrost landscape and Siberian peatlands represent globally important sources of the greenhouse gas methane. Under warming climate, feedback mechanisms will further enhance methane emissions. However, only few sites with continuous measurements of methane fluxes are available in the Russian Arctic and Siberia, and they serve as reference for estimations on regional scales. Further, local small-scale heterogeneities of land cover within a landscape are understood to be one of the main sources of the uncertainty in the observed methane fluxes. A combination of several measurement methods for high spatio-temporal resolution of methane fluxes as well as of the heat and moisture budget is needed. This lack of data limits further land-cover and emission model development. Therefore, the project MICHAEL aims at i) providing high spatio-temporal resolution of methane emissions, of the turbulent heat fluxes and the isotopic composition using novel observational techniques in addition to those commonly used and ii) further develop land-surface models and parameterizations by taking into account landscape heterogeneities more adequately. Two sites are chosen for field campaigns: the Samoylov Station in the Lena River Delta and Mukhrino in the central part of West Siberia. The special focus is on small-scale variability and the impact of contrasting landscape features. During the project, continuous ground-based methane fluxes obtained using eddy-covariance and automatic chamber methods are enhanced with additional ground-based observational sites and combined with unmanned aerial system (UAS) measurements of surface and meteorological parameters, components of the surface heat balance, methane fluxes, profiles of methane concentration and methane isotopic composition. Three UAS are applied: a fixed-wing system for meteorological measurements including turbulence and radiation, a quadrocopter for obtaining vertical profiles of the methane concentration and for taking air samples that are analyzed for methane isotopic composition, and a tiltrotor system providing fluxes of methane. The UAS are operated at different locations within a radius of up to 10 km around the observatories, depending on wind direction, atmospheric stability and land surface to enable footprint calculations. Based on the results the accuracy of traditional eddy-covariance and chamber methods is evaluated and upscaling/downscaling methods are revised.Numerical simulations are used to derive the 3D variability of methane emitted into the atmosphere, using land-surface modelling to represent turbulent exchange over heterogeneous surface, and high-resolution atmospheric modelling to embed the measurements in the context of synoptic conditions. A numerical land-surface model containing also the carbon cycle is adapted to the considered landscapes. The modelling results are evaluated against observations and the impact of landscape heterogeneities is quantified.

北极永久冻土景观和西伯利亚泥炭地代表着全球重要的温室气甲烷来源。在温暖的气候下，反馈机制将进一步增强甲烷排放。但是，俄罗斯北极和西伯利亚只有很少有具有连续测量甲烷通量的地点，它们可以作为估算区域尺度的参考。此外，景观中当地的小规模土地覆盖率被认为是观察到的甲烷通量中不确定性的主要来源之一。需要几种用于高时空分辨率的甲烷通量以及热量和水分预算的测量方法的组合。缺乏数据限制了进一步的土地覆盖和排放模型的开发。因此，Michael的目标是I）i）提供甲烷排放，湍流通量和同位素组成的高时空分辨率，并使用新颖的观察技术除了使用新颖的观测技术以及常用的ii）进一步开发地面模型和参数，通过考虑地面景观模型和参数化，以考虑地面景观的景观异质性。选择了两个地点进行现场活动：位于西西伯利亚中部的莉娜河三角洲和穆克里诺的萨摩洛夫站。特别的重点是小规模的变异性和对比鲜明的特征的影响。在项目期间，使用其他基于地面的观测位点增强了使用涡流和自动腔室方法获得的连续地面甲烷通量，并与无人驾驶的空中系统（UAS）测量相结合，对表面和气象参数的测量，表面热量平衡，甲烷浓度和甲烷浓度和甲烷浓缩的甲烷液位和甲烷浓缩的成分。应用了三个UAS：用于气象测量的固定翼系统，包括湍流和辐射，四倍型甲烷浓度的垂直剖面，并用于对甲烷同位素组合物进行分析的空气样品，以及提供甲烷升华的tiltrotor系统。根据风向，大气稳定性和陆地表面以实现足迹计算，在观测站周围的半径内的不同位置在不同位置进行操作。基于结果，评估了传统的涡流和腔室方法的准确性，并修订了进行缩放/缩减方法。数量模拟用于在大气层中使用土地表面建模来得出发射到大气中的甲烷的3D变异性，以代表异构的表面，高分辨率的大气建模，并在嵌入式构建中，以代表湍流。包含碳循环的数值土地表面模型也适用于所考虑的景观。对观察结果进行了评估，并量化了景观异质性的影响。