Comparison of calculation models for determination of the mesopause temperature using SATI images Original Research Article

The Spectral Airglow Temperature Imager is an instrument for ground-based spectroscopic measurements of the night-glow atmosphere emissions. This instrument was developed specially for gravity wave investigation. The measured airglow spectra are matched to synthetic spectra calculated in advance for determination of the temperature in the mesopause region where the radiation maximum of some О2 emissions is situated. The synthetic spectra are transformed into a format which corresponds to the measured spectra in order to be matched. This transformation is based on the known values of the refractive index and the central wavelength of the interference filter used. A substantial part of the processing algorithms of the SATI images is connected with determination of these two filter parameters. The results of the original and newly-proposed algorithms for filter parameter calculation and their importance for the final results for temperature determination on the basis of the О2 (864–868 nm) emission measurements are presented. Considerable systematic differences (∼20 K) between temperatures at different points in the mesopause retrieved by the two algorithms are established. The advantage of the proposed algorithm over the original one is illustrated by retrieved rotational temperatures and by lower error values. Furthermore, the irregular errors in the nocturnal variation of the temperature retrieved by the original algorithm are absent when the proposed approach is applied. The error investigation in the calculations and the stability of the individual components of the processing algorithms and the calculation models may be helpful in achieving better results and enhancing the potentialities of the SATI instrument.