Nighttime Atomic Hydrogen Abundance Retrieved From SCIAMACHY Hydroxyl Airglow Measurements in the Mesopause Region

Atomic hydrogen (H) is crucial for understanding photochemistry and the energy budget in the mesopause region. However, there is still no consensus on the H abundance in this region. This study presents a new hydrogen data set derived from Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) OH(9–6) band spectra, collocated with temperature and ozone profiles from other remote sensing instruments. H number densities peak at 82–87 km and range from (Formula presented.) to (Formula presented.) (Formula presented.), depending on season and latitude. Two other H data sets obtained from the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) are presented for comparison: those from Mlynczak et al. (2018, https://doi.org/10.1029/2018GL077377) and Panka et al. (2021, https://doi.org/10.1029/2020GL091053) are approximately 30% lower and 50% higher than the SCIAMACHY data at peak altitudes, respectively. Additionally, the H number density retrieved in this study partly shows better agreement with the only direct rocket in situ measurements than those from SABER.