几何光学冠层反射建模中的光谱分量特征的参数化(英文)

Parameterization of Spectral Component Signatures for Geometric Optical Canopy Reflectance Modeling

该文用几何光学与辐射传输混合模型研究不连续植被冠层的几何光学反射模型的四分量（承照树冠、承照地面、阴影树冠、阴影地面）的参数化。用一个修正的均匀介质层路径散射（反射与传输）参数的解析算法估计路径散射参数（反射与传输），其中也考虑了冠层间隙的影响。光谱分量特征是不连续植被冠层的传输与反射，背景反照率，以直射光通量与天空漫射光通量比例的函数。光谱分量特征的模型与在美国缅因州Ｈｏｌａｎｄ采集的针叶林数据吻合。基于ＬｉＳｔｒａｈｌｅｒ几何光学相互遮蔽模型，用参数化的光谱分量特征对老松林和老云杉林的方向反射进行估计，其结果与在不同太阳与观测方向上的ＰＡＲＡＢＯＬＡ测量值匹配得很好。

A hybrid geometric optical and radiative transfer approach is used to parameterize the four component spectral signatures (sunlit crown, sunlit background, shaded crown, and shaded background) in geometric optical reflectance models over discontinuous plant canopies. The path scattering parameters (transmittance and reflectance) are estimated using a modified version of the analytical solutions of path scattering parameters (reflectance and transmittance) for a homogeneous medium layer, which includes the effect of the canopy gaps. The spectral component signatures are functions of the transmittance and reflectance for discontinuous plant canopies, the background albedo and the proportions of incident beam and diffuse skylight. The modeled spectral component signatures show good agreement with data collected in a conifer forest in Holland, Maine. Using the parameterized spectral component signatures, estimates from Li and Strahler's geometric optical mutual shadowing model for directional reflectance over the old jack pine and old black spruce forests in the boreal ecosystematmosphere study (BOREAS), match well with PARABOLA measurements at different solar and viewing geometry.