On-flight calibration and atmospheric correction over city water for wide-field -of-view Hypersepctral Imager

Abstract

Radioactive calibration and atmospheric correction are two important steps when encountering a new sensor and its remote sensing images. Wide field-of-view Hyperspectral Imager(WHI) is an airborne imaging spectrometer with a 5nm spectral resolution, whose spectrum range is from 406nm to 985nm. For evaluating its applications in city water monitoring, a flight was carried out in Taihu in January 9, 2006, which was the third largest freshwater lake. Meanwhile, the in-situ measured spectra by ASD and measured atmosphere parameters by sun photometer CE318 were also obtained. It is an efficient way to monitoring change of the water-quality by airborne or satellite remote sensing data. To accurately retrieve water-quality parameters, two crucial recalibration processes were done for WHI: 1) Field recalibration was accomplished by comparing the two calibration targets' modeling radiance at sensor level and their lab calibrated radiance ; 2) Vicarious calibration was done by comparing the atmosphere corrected remote sensing reflectance (Rrs) with the in-situ measured Rrs of a synchronous station. Then, atmosphere correction Rrs was performed by 6SV1 model combined with Motran4 to retrieve Rrs of Taihu and the accuracy was no more than 5% from 532nm to 750nm validated by other synchronous stations.