Measurement and modelling of carbon emissions in snow-covered Arctic tundra and taiga biomes

在北极环境中，冷季碳排放对年度碳预算有很大贡献。由于北部高纬度地区气温的上升速度几乎是地球其他地区的四倍，量化这些环境的冷季碳通量对于了解它们对未来全球气温的影响至关重要。然而，北极冬季数据的收集在后勤和技术上都具有挑战性，在少数几个收集碳通量数据的地点，人们仍然对雪对这些通量的作用知之甚少。因此，现有的陆地生物圈模式不能很好地模拟冬季碳通量，这是因为缺乏强迫数据，也不能很好地描述北极积雪对陆地-雪-大气相互作用的影响。该项目旨在确定北极积雪的热导率和结构对北部北方森林-冻原交错带冬季生态系统和陆地-地表碳交换的作用，这两个研究点位于因努维克附近(加拿大西北地区)。为了在多个空间尺度上量化雪对碳通量的影响，将开发低成本传感器，在利用涡旋协方差测量景观和生态系统尺度碳通量的足迹范围内，沿垂直剖面测量积雪的二氧化碳和甲烷浓度、温度和密度(Baldocchi 2003)。有了这个新的数据集，TBM(例如，社区陆地模型-CLM5.0)的不确定性将受到改进的基于过程的冬季碳通量表示的约束。项目成果将有助于通过更好的地球系统过程数据和模型提高气候变化预测的准确性。

Cold season carbon emissions make a significant contribution to annual carbon budgets in Arctic environments. With air temperature in northern high latitudes increasing at rates nearly four times faster than the rest of the Earth, quantifying cold season carbon fluxes from these environments is crucially important for understanding their impact on future global air temperatures. However, winter data collection in the Arctic is logistically and technically challenging, and at the few sites where carbon flux data is collected the role of snow on these fluxes is still poorly understood. Consequently, current Terrestrial Biosphere Models (TBMs) are unable to adequately simulate wintertime carbon fluxes, due to both a lack of forcing data and inadequate representation of the effect of Arctic snow cover on land-snow-atmosphere interactions. This project aims to determine the role of Arctic snowpack thermal conductivity and structure on wintertime ecosystem and land-surface carbon exchanges across the northern boreal forest - tundra ecotone at two research sites near Inuvik (Northwest Territories, Canada). To quantify the effect of snow on carbon fluxes at multiple spatial scales low-cost sensors will be developed to measure snowpack CO2 and CH4 concentrations, temperature, and density along vertical profiles within the footprint of landscape- and ecosystem-scale carbon flux measurements made with eddy covariance (Baldocchi 2003). With this novel dataset, TBM (e.g., Community Land Model - CLM5.0) uncertainties will be constrained by improved process-based representations winter carbon fluxes. Project outcomes will contribute to improving accuracy in climate change predictions through better earth system process data and models.