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

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（boreal evergreen needleleaf forests）内季节光谱特征如何响应物候阶段变化。本数据集收录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黑云杉（black spruce）林内布设了两套野外光谱辐射计（spectroradiometer）系统，分别用于获取冠层尺度（上层林冠+下层植被）与下层植被的反射率数据。本数据集包含上层林冠与下层植被的入射及反射半球光谱辐照度（hemispherical spectral irradiance）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）。因上层林冠观测所用的反射半球光谱辐照度数据包含观测塔架结构产生的反射信号，研究团队针对塔顶层级的观测数据进一步开展了反射率校正处理，对应Level 3数据集。