Abstract: The data set presented here consists of a case study in the framework of the DFG-project ICECREAM (Analysis of high-latitude cirrus cloud feedbacks on the trace gas composition of the UTLS), and comprises observations of the trace gases water vapour (H2O), ozone (O3), nitric acid (HNO3) and clouds in the upper troposphere/lowermost stratosphere (UT/LMS) by the infrared remote sensing instrument GLORIA (Gimballed Limb Observer for Radiance Imaging of the Atmosphere), and the corresponding model data of dedicated simulations with the numerical weather prediction (NWP)-model ICON (ICOsahedral Nonhydrostatic) with the extension ART (Aerosols and Reactive Trace gases), and the chemistry-climate model (CCM) EMAC (ECHAM5/MESSy Atmospheric Chemistry). The data cover one research flight during the Arctic winter 2015/2016, when GLORIA was deployed on-board the German Research aircraft HALO (High Altitude and LOng range research aircraft) during the POLSTRACC (POLar STRAtosphere in a Changing Climate), GW-LCYCLE (Gravity Wave Life Cycle Experiment) II and SALSA (Seasonality of Air mass transport and origin in the Lowermost Stratosphere using the HALO Aircraft) (PGS) field campaign. This joint campaign probed the Arctic UT/LMS during different stages of the winter 2015/2016. The analysed research flight here, PGS 14, on 26 February 2016, covered deeply subsided air masses of the aged Arctic vortex, high-latitude LMS air masses, a highly textured troposphere-to-stratosphere exchange region, and high-altitude cirrus clouds. Therefore, it provides the opportunity to test state-of-the-art atmospheric model simulations in a complex UT/LMS region at a late stage of the Arctic winter 2015/2016. Details on the data are provided in the file “ReadMe.pdf”.