Strong persistent cooling of the stratosphere after the Hunga eruption

The 2022 eruption of the Hunga volcano was a major event that propelled aerosols and water vapor up to an altitude of 53-57 km. It caused an unprecedented stratospheric hydration that is expected to affect composition, thermal structure, circulation and dynamics for years. Using vertically high resolved satellite observations from radio occultation, we focus on the temperature impact in the stratosphere from the eruption in January 2022 until December 2023. Separating the signals of the Hunga eruption from the broader stratospheric variability reveals a strong persistent radiative cooling of up to -4 K in the tropical and subtropical middle stratosphere from early after the eruption until mid-2023, clearly corresponding to the water vapor distribution. Our results provide new insights from observations into both the localized temperature changes and the persistent stratospheric cooling caused by the Hunga eruption and document this exceptional climatic effect not seen for previous volcanic eruptions.