Comment on egusphere-2025-5470

Abstract. The stratopause, the boundary between the stratosphere and the mesosphere, is projected to cool and drop in response to anthropogenic greenhouse gas (GHG) emissions. A lack of long-term observations with high vertical resolution at the stratopause has made it difficult to quantify trends in this region. We use observations from the Optical Spectrograph and InfraRed Imager System (OSIRIS) and the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument to assess the annual and inter-annual variability and to quantify trends in the stratopause temperature and height. The SABER and OSIRIS observations at the stratopause are highly correlated, and both show that the stratopause cooled by ~0.5–1 K per decade during 2005–2021. The observations also suggest that the tropical stratopause moved lower during this time period by 300–475 m per decade. The observational stratopause trends are consistent with trends from chemistry climate models simulations.