@Article{Li2015,
author="Li, Li
and Du, Yongming
and Tang, Yong
and Xin, Xiaozhou
and Zhang, Hailong
and Wen, Jianguang
and Liu, Qinhuo",
title="A New Algorithm of the FPAR Product in the Heihe River Basin Considering the Contributions of Direct and Diffuse Solar Radiation Separately",
journal="Remote Sensing",
year="2015",
volume="7",
number="5",
keywords="FPAR;direct radiation;diffuse radiation;radiative transfer model",
abstract="It remains a challenging issue to accurately estimate the fraction of absorbed photosynthetically-active radiation (FPAR) using remote sensing data, as the direct and diffuse radiation reaching the vegetation canopy have different effects for FPAR. In this research, a FPAR inversion model was developed that may distinguish direct and diffuse radiation (the DnD model) based on the energy budget balance principle. Taking different solar zenith angles and diffuse PAR proportions as inputs, the instantaneous FPAR could be calculated. As the leaf area index (LAI) and surface albedo do not vary in a short periods, the FPAR not only on a clear day, but also on a cloudy day may be calculated. This new method was used to produce the FPAR products in the Heihe River Basin with the Moderate-Resolution Imaging Spectroradiometer (MODIS) LAI and surface albedo products as the input data source. The instantaneous FPAR was validated by using field-measured data (RMSE is 0.03, R<sup>2</sup> is 0.85). The daily average FPAR wa..."
}