AIRBORNE HYPERSPECTRAL SCANNER (AHS) SPECTRAL EMISSIVITY RETRIEVAL IN 8-13 μm

Multispectral and hyperspectral thermal sensors can use spectral emissivities for mapping surface elements that show wavelength emission differences (typically minerals). The Airborne Hyperspectral Scanner (AHS) is a VIS to TIR 80 band line-scanner which collects 10 bands in the 8 to 12 μm atmospheric window, with 0.4 μm bandwidth. Multichannel temperature-emissivity separation published methods (Reference Channel and Emissivity Normalization) are evaluated here to estimate the capacity of AHS to retrieve spectral emissivity. These methods are very dependent on an accurate calibration and atmospheric correction of the at-sensor radiances, and also sensitive to the noise equivalent difference temperature (NEΛT) of the channels. Emissivities obtained for some AHS 2005/2006 imagery campaigns, including day and night flights, have been tested comparing with emissivity ground truth (collected at SEN2FLEX ESA 19187/05/I-EC project) and spectral libraries available in the 8-13 μm region.