Research Of FPAR Estimation Method Based On Medium-high Spatial Resolution Remote Sensing Data

The Fraction of Photosynthetic Active Radiation(FPAR)is one of the key variables that Global Climate Observation System(GCOS)proposed.FPAR refers to the ratio of photosynthetic effective radiation(400-700nm,PAR)absorbed by vegetation accounting for all effective radiation reaching the top of canopy.FPAR is closely related to vegetation structure and can represent the capacity of vegetation to absorb photosynthetic effective radiation.FPAR obtained by remote sensing can be used to monitor the health and growth status of vegetation worldwide.Research on vegetation monitoring,agriculture,ecosystem,carbon cycle,regional and global scale climate change is of great importance.Meanwhile,FPAR is an important input parameter for remote sensing estimation of total primary productivity and net primary productivity of terrestrial ecosystem vegetation.This paper probes the FPAR inversion method according to medium-high spatial resolution remote sensing data,and the main contents include:(1)Selecting Inner Mongolia Xilin Gol League,Heilongjiang Friendship Farm,Longyuan Farm in Anhui Province,and Beijing Xiaotangshan National Precision Agriculture Research Demonstration Base for data collection.The sample size is 1.5 meters*1.5 meters.The hyperspectral data of the vegetation was collected using the ASD FieldSpec Pro.The measured FPAR of each plot was measured and acquired using the SUNSCAN canopy analyzer.The comparative analysis of FPAR retrieval and ground measured FPAR is carried out.The optimal vegetation index for FPAR-SR model is discussed.The sensitivity analysis of FPAR to LAI and observation angle is studied.Finally,estimating the FPAR of the Huanghuaihai area by using the vegetation index of NDVI and EVI.(2)Researching on FPAR estimation method based on energy balance.The absorption,reflection and transmission of illumination by vegetation canopy is an energy balance process.Constructing a FPAR inversion method based on the radiation transfer equation by considering the energy of each part.This paper analyzes the interaction between solar radiation and vegetation.This research proposing an energy balance based FPAR estimation method.The method is used to invert the FPAR results of the high spatial resolution of the Xiong'an New District in 2017,and the inversion accuracy is high.The method starts from the mechanism and has few input parameters and can be used to generate high-resolution FPAR products.(3)Researching on FPARgreen estimation method based on PROSAIL model.Plant canopy is mainly composed of effective photosynthesis part and non-photosynthetic part.Non-photosynthetic part(dry,stem,dead leaf)has great influence on canopy FPAR.This study is based on PROSAIL model to explore canopy FPAR and chlorophyll FPAR.Exploring the relationship between FPARgreen and vegetation index,to provide a possibility to invert FPARgreen.