Using Data of HJ1A HSI for Retrieving Grassland Leaf Area Index

Abstract

Leaf area index(LAI) is one of the key parameters for quantifying the energy and mass exchange characteristics of terrestrial ecosystems.To validate the feasibility of using HJ-1A HSI data to retrieve leaf area index,HJ-1A HSI data was acquired from China Center for Resource Satellite Data and Applications while in situ LAI was collected with a LAI-2000 sensor.Based on the field experiment data,an evaluation of grass LAI retrieval methods was conducted using three vegetation indices including ratio vegetation index(RVI),normalized difference vegetation index(NDVI) and modified soil adjusted vegetation index(MSAVI).The results showed that the three vegetation indices derived from HSI data have good relationship with measured LAI.MSAVI gained the best result with R2 value of 0.622.While the cross validation result of MSAVI model was also permissible with R2 value of 0.547 and RMSE value of 0.202.All the above showed that the measured LAI and simulated LAI have good consistency.At last,the map of grass LAI,which could partially reflect the growing status of the pasture,was produced using HJ-1A HSI data and MSAVI model.