NGEE Arctic Leaf Spectral Absorptance, Utqiagvik (Barrow), Alaska, 2015-2016

Leaf level reflectance on each sample leaf was measured using a portable, full range (i.e. 0.35 to 2.5 microns) Spectra Vista Corporation (SVC) HR-1024i spectroradiometer, together with a leaf clip assembly with an internal, calibrated light source (SVC, Poughkeepsie, NY, USA). Each measurement was referenced against a LabSphere Spectralon (R) standard (LabSphere, Inc., North Sutton, NH, USA) to calculate leaf reflectance from the ratio of target and standard calibrated radiance measurements for each leaf. For each leaf, we collected two to five measurements over the leaf adaxial surface to calculate an average, depending on the leaf size and morphology. Spectral discontinuities in the detector overlap areas were corrected using the SVC instrument software prior to sample averaging and other quality control steps, as described previously (Serbin et al., 2014) using the R-FieldSpectra package (https://github.com/serbinsh/R-FieldSpectra). Refer to Serbin et al (2017) for the complete spectral reflectance dataset. We then calculated leaf spectral absorptance using the measured leaf reflectance following the approach of Wu et al., (2018), based on the original method derived by Shiklomanov et al., (2016) using the PEcAnRTM package (https://github.com/PecanProject/pecan/tree/develop/modules/rtm). This dataset contains one xlsx file, one csv file, and one pdf file. The Next-Generation Ecosystem Experiments: Arctic (NGEE Arctic), was a research effort to reduce uncertainty in Earth System Models by developing a predictive understanding of carbon-rich Arctic ecosystems and feedbacks to climate. NGEE Arctic was supported by the Department of Energy's Office of Biological and Environmental Research. The NGEE Arctic project had two field research sites: 1) located within the Arctic polygonal tundra coastal region on the Barrow Environmental Observatory (BEO) and the North Slope near Utqiagvik (Barrow), Alaska and 2) multiple areas on the discontinuous permafrost region of the Seward Peninsula north of Nome, Alaska. Through observations, experiments, and synthesis with existing datasets, NGEE Arctic provided an enhanced knowledge base for multi-scale modeling and contributed to improved process representation at global pan-Arctic scales within the Department of Energy's Earth system Model (the Energy Exascale Earth System Model, or E3SM), and specifically within the E3SM Land Model component (ELM).

采用便携式全波段（0.35~2.5微米）Spectra Vista Corporation（SVC）HR-1024i型光谱辐射计，配套内置校准光源的叶片夹持组件（SVC，美国纽约州波基普西市），对每份样品叶片的叶片级反射率进行测量。每次测量均以LabSphere Spectralon®标准白板（LabSphere公司，美国新罕布什尔州北萨顿）作为参照，通过目标与标准校准辐射亮度的比值计算单叶反射率。根据叶片大小与形态，我们在每张叶片的近轴面采集2~5组测量值以计算平均反射率。如先前研究（Serbin等，2014）所述，在样本平均与其他质量控制步骤前，使用SVC仪器软件对探测器重叠波段的光谱不连续性进行校正，校正过程依托R-FieldSpectra软件包（https://github.com/serbinsh/R-FieldSpectra）完成。完整的光谱反射率数据集可参考Serbin等（2017）的研究。随后基于Shiklomanov等（2016）提出的原始方法，参考Wu等（2018）的研究路径，利用实测叶片反射率计算叶片光谱吸收率，计算过程依托PEcAnRTM软件包（https://github.com/PecanProject/pecan/tree/develop/modules/rtm）完成。本数据集包含1个XLSX文件、1个CSV文件与1个PDF文件。下一代生态系统实验：北极（Next-Generation Ecosystem Experiments: Arctic, NGEE Arctic）是一项旨在通过深化对富碳北极生态系统及其气候反馈机制的预测性认知，降低地球系统模型不确定性的研究项目。NGEE Arctic项目由美国能源部生物与环境研究办公室资助。该项目设有两个野外研究站点：1）位于美国阿拉斯加州Utqiagvik（原巴罗）附近北坡的巴罗环境观测站（Barrow Environmental Observatory, BEO）内的北极多边形苔原沿海区域；2）位于阿拉斯加州诺姆以北苏华德半岛不连续永久冻土区的多处区域。通过观测、实验与现有数据集的综合分析，NGEE Arctic项目为多尺度建模提供了更为完善的知识库，并推动了美国能源部地球系统模型（能源超额计算地球系统模型，Energy Exascale Earth System Model, E3SM），尤其是E3SM陆面模型模块（ELM）在全球泛北极尺度下的过程表征精度提升。