Exploratory Continuous Multispectral Reflectance Measurements at Harvard Forest

摘要/摩尔 本研究的主要目的是探讨中纬度落叶林地表反射率的季节变化与蒸散量的关系。 具体目标是： 1.为了探测某些重要波段的地表反射率的季节变化，并将这些变化与冠层液态水含量联系起来， 2.通过对水汽输送的表面阻力，将反射率测量与表面湍流能量通量，特别是蒸散联系起来， 3.在双周合成图中比较窄带多光谱反射率与卫星宽带反射率（可见光和近红外）的季节变化。 4.根据已发表的方案，利用上视阴影波段仪器反演的气溶胶光学厚度计算卫星数据的大气校正。 本研究的总体目标是利用地面遥感技术改进对地表能量和痕量气体通量的间接测量。 研究者建议研究森林冠层反射率的季节变化及其与地面湍流能量交换的关系。 植被通过控制地表能量和微量气体的通量，特别是蒸散量，对区域气候产生重要影响。 这项拟议的研究是马萨诸塞州哈佛森林一项独特的、正在进行的长期测量计划的逻辑发展;该研究已经产生了结果，表明冠层辐射特性（近红外反射率、热响应）的某些季节性变化可能与蒸散有关。 研究人员建议补充正在进行的湍流能量通量和辐射测量计划在哈佛森林与向上看和向下看的多过滤器旋转阴影波段辐射计。

ABSTRACT/Moore The general objective of this research is to relate seasonal changes in narrow-band surface reflectance to evapotranspiration in mid-latitude deciduous forest. The specific objectives are: 1. To detect seasonal change in surface albedo (reflectance) in certain important wavebands, and link these changes to canopy liquid water content, 2. To relate reflectance measurements to surface turbulent energy fluxes, especially evapotranspiration, through the surface resistance to water vapor transfer, 3. To compare seasonal changes in narrow-band multispectral reflectance with satellite broadband reflectance (visible and near- infrared) in biweekly composites. 4. To use the aerosol optical depths retrieved from the upward-looking shadowband instrument to calculate atmospheric corrections for satellite data, according to published schemes. The overall goal of this study is to improve indirect measurements of surface energy and trace gas fluxes using surface- based remote sensing techniques. The investigator proposes to study seasonal changes in forest canopy reflectance and its relationship to surface turbulent energy exchange. Vegetation exerts a strong influence on regional climate through control of the surface fluxes of energy and trace gases, especially evapotranspiration. This proposed study is a logical development form a unique, ongoing long-term measurement program at Harvard Forest in Massachusetts; that study has yielded results indicating that certain seasonal changes in canopy radiative properties (near- infrared reflectance, thermal response) can be related to evapotranspiration. The investigator proposes to complement the ongoing turbulent energy flux and radiation measurement program at Harvard Forest with both upward-looking and downward-looking Multifilter Rotating Shadowband Radiometers.