A Correction Methodology for Cross-Track Instrument Biases in Airborne Hyperspectral Thermal Infrared Data Over the Cryosphere

The Hyperspectral Thermal Emission Spectrometer (HyTES) is an airborne sensor measuring surface-leaving thermal infrared radiation (TIR) with 256 bands in the 7.5-12 µm spectral range. During its 2023 deployment over the Swiss Alps, as part of a large European campaign, instrument-related crosstrack radiometric biases were identified. We present a correction methodology tailored to glaciers. The method exploits physically constrained radiance over melting ice to derive wavelength-and pixel-specific correction factors. Developed on one flightline and applied on all six HyTES flightlines, the correction successfully reduced cross-track inconsistencies and striping artifacts. Validation with in-situ data results in a mean absolute deviation of 1.75 K, which improved by 5.3 K compared to the uncorrected data. The method can also be applied to other homogeneous surfaces, such as open water bodies or bare sand, and the corrected dataset provides unprecedented opportunities for glacier studies.