Operational Atmospheric Correction for Imaging Spectrometers Accounting for the Smile Effect

Hyperspectral pushbroom imagers are affected by a number of artifacts, such as pixel nonuniformity, spectral smile, and keystone. These have to be taken into account during system correction, orthorectification, or atmospheric correction, as performed in processing and archiving facilities (PAFs). This contribution is presenting an efficient and accurate smile correction method integrated in the atmospheric correction. The proposed technique will be used in the PAF of the German hyperspectral Environmental Mapping and Analysis Program mission. The spectral smile shift across the detector array is parametrized with a fourth-order polynomial function for each channel based on the instrument optical design model or measured laboratory data. Alternatively, spectral smile shifts can be calculated from image data using channels in atmospheric absorption regions. The concept for the time-optimized processor is outlined, and the results are presented for simulated EnMAP data and existing pushbroom imagery [HYPERION, AISA (Airborne Imaging Spectrometer for Applications), and HYSPEX (Hyperspectral Camera)].