Evaluation of atmospheric correction using FLAASH

This paper evaluated the capability of FLAASH in ENVI software to make atmospheric correction for Hyperion hyperspectral image and ALI image. Hyperion and ALI sensors are two of the three instruments onboard NASA EO-1 satellite, New Millennium Program (NMP) launched on November 21, 2000, and Hyperion is the first spaceborne hyperspectral imaging spectrometer. The study area is Zhangye city (37°28’N–39°57’N, 97°20’E–102°12’E) in Heihe River valley of Gansu province, China. Using TM data with UTM projection, Hyperion hyperspectral data acquired on September 10, 2007 and ALI data on September 20, 2007 were geometrically and radiometrically corrected, and then atmospherically corrected using FLAASH. Surface reflectance spectra of corn, water body, desert and buildings were extracted from these two images and made comparison with apparent reflectance. Canopy reflectance spectra of corn were recorded using ASD Fieldspec spectroradiometer in near-real time to coincide with EO-1 satellite sensor overpass. According to filter function of ALI and central wavelength and Gaussian filter function based on full width at half maximum (FWHM) of Hyperion, the ASD reflectance spectra were resampled to corresponding Hyperion and ALI bands. Results showed that resampled ASD spectra of corn were consistent with spectra on Hyperion and ALI images after FLAASH. This demonstrated the effectiveness of atmospheric correction using FLAASH.