Continuous canopy and understory spectral reflectance measurements of a sparse black spruce forest at Poker Flat Research Range (PFRR), interior Alaska (Year 2018)

Plant phenology timings, such as spring green-up and autumn senescence, are essential state information characterizing biological responses and terrestrial carbon cycles. Current efforts for the in-situ reflectance measurements are not enough to obtain the exact interpretation of how seasonal spectral signature responds to phenological stages in boreal evergreen needleleaf forests. This data set shows the in situ continuous measurements of spectral reflectance in a boreal forest in interior Alaska. We deployed two field-based spectroradiometer systems in an open black spruce forest. These two spectroradiometer systems were used to obtain canopy scale (overstory + understory) and understory reflectances. The data set includes the overstory and understory incoming and reflected hemispherical spectral irradiance data (Level 1), and spectral reflectance computed by the in- and out-going spectral data (Level 2). Because the reflected hemispherical irradiance contains the reflection from tower structure for overstory measurements. The further reflectance correction was applied for the measurements at the tower top level (Level 3).

植物物候期（如春季返青与秋季衰老）是表征生物响应与陆地碳循环的核心状态信息。当前原位（in-situ）反射率测量工作尚不足以精准阐释北方常绿针叶林内季节性光谱特征如何响应物候阶段变化。本数据集呈现了阿拉斯加内陆一处北方森林的光谱反射率原位连续观测数据。研究团队在一片开阔的黑云杉林内部署了两套野外光谱辐射计系统，该两套系统分别用于获取林冠尺度（乔木层+林下层）与林下层的反射率数据。数据集包含乔木层与林下层的入射及反射半球光谱辐照度数据（Level 1），以及由入射与出射光谱数据计算得到的光谱反射率数据（Level 2）。由于乔木层测量所用的反射半球光谱辐照度包含了铁塔结构产生的反射信号，因此针对铁塔顶端位置的观测数据开展了进一步的反射率校正处理，即Level 3数据。