Measurement of the spectral directional reflectance of forest canopies: A review of methods and a practical application
Measurement of the spectral directional reflectance of forest canopies: A review of methods and a practical application
复制标题
森林冠层光谱定向反射率的测量：方法回顾和实际应用
DOI：
--
复制
发表时间：
1994
期刊：
影响因子：
--
通讯作者：
F. Danson
中科院分区：
文献类型：
--
作者：
E. Milton;G. A. Blackburn;E. Rollin;F. Danson
摘要本文综述了森林冠层光谱定向反射率的测量方法，并探讨了利用直升机平台采集落叶林光谱反射率数据的方法。确定了六种稀疏采样几何形状：天底、热点、太阳almucantar、太阳主平面、正交平面和孪生方位角平面。从直升机上使用便携式分光辐射计测量150至760米高度的橡树（Quercus robur）种植园的最低反射率。从150米和地面高度对割下的草地区域进行近乎同时的反射率测量，用于校正旋翼叶片对直升机测量的辐照度的影响。从940毫微米处大气吸收特征的相对深度可以推断出水汽量随高度和相距30公里的两个地点之间的变化。
Abstract In this paper we review methods to measure the spectral directional reflectance of forest canopies and investigate the use of a helicopter platform to gather spectral reflectance data from deciduous forest. Six sparse sampling geometries are identified: nadir, hot‐spot, solar almucantar, solar principal plane, orthogonal plane and twin azimuthal planes. A portable spectroradiometer is used from a helicopter to measure the nadir reflectance of an oak (Quercus robur) plantation at heights from 150 to 760 metres. Near‐simultaneous reflectance measurements of an area of mown grass from 150 metres and ground level are used to correct for the effect of the rotor blades on the irradiance measured from the helicopter. Variations in the amount of water vapour with height and between two sites 30 km apart are inferred from the relative depth of the atmospheric absorption feature at 940 nm.