Joint observations of oxygen atmospheric band emissions using OSIRIS and the MATS satellite

Abstract. The MATS (Mesosphere, Airglow/Aerosol, Tomography & Spectroscopy) satellite was launched in November 2022 and began collecting scientific measurements of the Mesosphere and Lower Thermosphere (MLT) in early 2023. The satellite utilises a multichannel limb-viewing instrument designed to gather images across six distinct spectral bands, each selected to capture atmospheric airglow from O₂ atmospheric band emissions as well as light scattered by noctilucent clouds (NLC). This article presents a comparison between the MATS limb measurements and the observations made by the OSIRIS spectrograph on the Odin satellite. Specifically, airglow signals from excited O₂, as recorded by MATS infrared (IR) channels and OSIRIS, are analysed over the polar regions under temporally and spatially aligned conditions. From December 2022 to February 2023, 36 close encounters of the two satellites were identified and analysed. The results show that the two instruments agree well on the overall structure but that the MATS signals generally exceed OSIRIS by ~20 % in magnitude. OSIRIS measurements are also compared to the radiative transfer model SASKTRAN, to investigate straylight impact on the measurements.