Stratospheric Constituent and Temperature Responses to the Hunga Volcanic Eruption and QBO in the Southern Hemisphere Low to Midlatitudes

Abstract Stratospheric temperature, ozone, and constituent observations show significant perturbations in the 1–2 years following the January 2022 Hunga volcanic eruption. This study uses GSFC2D model simulations forced with satellite‐based Hunga aerosol and water vapor anomalies to investigate the resulting impacts in the Southern Hemisphere stratosphere (tropics to midlatitudes) during the 2¼ years following the eruption. The relative impacts of the volcanic forcings are quantified and compared with dynamical changes caused by the quasi‐biennial oscillation (QBO), which exerts a substantial influence. Largest volcanic‐driven chemical and radiative changes occur during 2022 and gradually diminish thereafter. Significant model enhancements in HNO 3 and ClO, and corresponding reductions in NO 2 and HCl, are driven by the Hunga aerosol via heterogeneous reactions, and the Hunga water vapor perturbation via gas‐phase reactions. However, for model ozone, the net volcanic chemical impacts are small. For total column ozone, the aerosol‐induced effects are mostly negative with maximum changes of −3 DU, while the water vapor‐induced impacts are mostly positive with maximum changes of ∼+1 DU. Simulated total ozone anomalies driven by transport are significantly larger (±5–12 DU), consistent with previous studies. Model temperature anomalies are driven mainly by a combination of the QBO (±1–2 K) and radiative cooling of the Hunga H 2 O plume (−2–3 K). The Hunga aerosol had a minor impact on stratospheric temperature, causing a net warming of at most +0.5 K.