A novel infrared imager for studies of hydroxyl and oxygen nightglow emissions in the mesopause above northern Scandinavia

Abstract

The paper describes technical characteristics and presents the first scientific results of a novel infrared imaging system (imager) for studies of nightglow emissions coming from the hydroxyl (OH) and molecular oxygen (O2) layers in the mesopause region (80-100ĝ€¯km) above northern Scandinavia. The OH imager was put into operation in November 2022 at the Swedish Institute of Space Physics in Kiruna (67.86°ĝ€¯N, 20.42°ĝ€¯E; 400ĝ€¯m altitude). The OH imager records selected emission lines in the OH(3-1) band near 1500ĝ€¯nm to obtain intensity and temperature maps at around 87ĝ€¯km altitude. In addition, the OH imager registers infrared emissions coming from the O2 IR A-band airglow at 1268.7ĝ€¯nm in order to obtain O2 intensity maps at a slightly higher altitude, around 94ĝ€¯km. This technique allows the tracing of wave disturbances in both horizontal and vertical domains in the mesopause region. Validation and comparison of the OH(3-1) rotational temperature with collocated lidar and Aura Microwave Limb Sounder (MLS) satellite temperatures are performed. The first scientific results obtained from the OH imager for the first winter season (2022-2023) are discussed.