植被FAPAR的遥感模型与反演研究

Remote Sensing Retrieval of FAPAR:Model and Analysis

FAPAR是遥感估算陆地生态系统植被净第一性生产力(NPP)的重要参数。FAPAR模型是否能真实反映植被冠层吸收光合有效辐射状况,将直接影响遥感估算植被NPP和碳循环的准确性。从FAPAR机理出发,考虑土壤反射率、冠层结构、太阳入射角等多种因素,构建了全新的定量FAPAR反演模型,并分析了太阳天顶角、LAI、土壤背景等因素与FAPAR的关系。与蒙特卡罗模拟结果的对比和用地面实测数据的验证表明该模型拥有较高的精度。选择甘肃张掖盈科灌区为研究区,利用PROBA-CHRIS高光谱多角度数据反演得到了LAI和FAPAR,并用同步观测数据验证了反演结果。

FAPAR （ Fraction of Absorbed Photosynthetically Active Radiation） is an important parameter for remote sensing monitoring plants net primary productivity （NPP） of land ecosystem. It is crucial that the calculated value approximates the actual value of canopy absorbed photosynthetically active radiation. The calculation accuracy directly influences the estimation of NPP and carbon cycle. The model in this paper is derived by analyzing the interaction processes between the photons and the canopy. It considers parameters like soil reflectance, canopy structure and solar zenith angle, etc. The relationship between these parameters and FAPAR is analyzed. The comparison results with Monte Carlo simulations and the validation results using field measurements prove the model to be accurate. We further choose Yingke, Zhangye City, Gansu province as study area, and retrieve LAI and FAPAR from hyperspectral and multi-angle PROBA-CHIRIS. Field data is also used to validate the retrieval result.