Variability of Reactive Nitrogen Species and Ozone linked to the Stratospheric QBO

In the stratosphere, reactive nitrogen species (NOy), including nitrogen oxides (NOx = NO + NO₂) are produced through the oxidation of nitrous oxide (N₂O) and are closely linked with stratospheric ozone (O₃) through catalytic cycle. Interannual variability of NOy and O₃ are influenced by large-scale circulation related to the stratospheric quasi-biennial oscillation (QBO) in the tropics. In this study, we examine variability of nitrogen species, and their links with O₃, using 10 years (2005-2014) of satellite measurements from the Optical Spectrograph and InfraRed Imaging System (OSIRIS) instrument onboard the Odin spacecraft, together with the measurements of O₃ and nitric acid (HNO₃) from the Aura Microwave Limb Sounder (MLS). NOx proxy (= NOx*) is constructed based on OSIRIS measurements of NO₂ and photochemical box model calculations. We furthermore compare observations with simulations from the Whole Atmosphere Community Climate Model (WACCM4) global community climate model. Simulations of nitrogen species from WACCM4 enable a comprehensive analysis of the NOy budget and their variations linked to the QBO. We find good agreement between the satellite observations and the model simulations.