关键词: FPAR, 植被指数, SEVI, 地形校正, 本影, 落影, 复杂地形山区

Abstract:

The retrival of Fraction of Absorbed Photosynthetically Active Radiation (FPAR) by remote sensing is one of the major research fields in ecological environment. However, in mountainous areas with rugged terrain, the estimation accuracy is seriously affected by terrain effect, including the influence of self and cast shadow. In this paper, Shadow-Eliminated Vegetation Index (SEVI), which can effectually remove the influence of terrain shadow, was used to conduct FPAR inversion in mountainous areas from remote sensing data. The inversion result based on SEVI was compared and analyzed with the inversion results based on Normalized Difference Vegetation Index (NDVI) and Ratio Vegetation Index (RVI) with different pre-processing degrees and evaluate the topographic effect of FPAR inversion based on different indexes in complex mountainous areas from remote sensing images. The results show that the FPAR inversion based on NDVI and RVI have much smaller values in self and cast shadow areas than that in non-shadow area without terrain correction using DEM data, their relative error are both greater than 70%. C correction can be better used in the pre-processing of NDVI and RVI deriving and effectually corrected the FPAR inversion results based on these two indexes, its relative error dropped to about 6.974%. But the results after C correction not performed well in cast shadow areas, its relative error is about 48.133%. The FPAR inversion based on the SEVI without DEM data can achieve similar results with the FPAR inversion based on NDVI and RVI after the atmospheric correction of the FLAASH and C combination, and the result shows a better terrain correction effect in shadow area where relative error dropped to about 2.730%.

Key words: FPAR, vegetation indices, SEVI, topographic correction, self shadow, cast shadow