An error and sensitivity analysis of atmospheric resistant vegetation indices derived from dark target-based atmospheric correction

Abstract

An error and sensitivity analysis was conducted to investigate the capabilities of the atmospheric resistant vegetation indices (VIs) for minimizing “residual aerosol” effects. The residual aerosol effects result from the assumptions and characteristics of the dark target (DT) approach used to estimate aerosol optical properties in the atmospheric correction scheme (referred to as the dark target-based atmospheric correction, DTAC). The performances of two atmospheric resistant VIs, the atmospherically resistant vegetation index (ARVI) and enhanced vegetation index (EVI), were evaluated and compared with the normalized difference vegetation index (NDVI) and soil adjusted vegetation index (SAVI). The atmospheric resistant VIs successfully minimized the residual aerosol effects, resulting in a 60% reduction of the errors from the NDVI and SAVI when a proper aerosol model was used for the estimation and correction of aerosol effects. The reductions were greater for thicker aerosol atmosphere (larger aerosol optical thickness, AOT). The atmospheric resistant VIs, however, resulted in having larger bias errors than the NDVI and SAVI when an improper aerosol model was used. The application of atmospheric resistant VIs to the DTAC-derived surface reflectances is exactly what is being carried out by the Moderate Resolution Imaging Spectroradiometer (MODIS) VI algorithm. These results raise several issues for the effective, operational use of the DTAC algorithm and atmospheric resistant VIs, which are addressed in this paper.