Rapid destruction of stratospheric ozone due to massive injection of water vapour by the Hunga Tonga-Hunga Hapa’ai volcano.

(credit: René Carayol, Université de la Réunion)

On January 15, 2022, the eruption of the Hunga Tonga-Hunga Ha’apai volcano severely disturbed the upper atmosphere, emitting ash, sulfur dioxide (SO2) and other gases, as well as an exceptional quantity of water vapor (around 150 million tons) into the stratosphere at an altitude of over 30 km. This rare event was an opportunity to study chemical processes in a volcanic plume shortly after an eruption from the Maïdo observatory. Volcanic eruptions can affect climate and ozone chemistry. Understanding these interactions is essential to improve modeling of environmental processes and future climate evolution.

Our study combined in situ measurements from weather balloons, ground-based remote sensing observations and satellite data to understand the initial impact of the eruption on stratospheric ozone. In just one week, stratospheric ozone concentrations over the south-west Pacific and Indian Oceans fell by 5%. This decrease is particularly significant when compared to the Antarctic ozone hole, where up to 60% of the ozone is destroyed each year over several months. The humidification of the stratosphere after the eruption enabled the rapid formation of small droplets of sulfuric acid from SO2. On the surface of these particles, chemical reactions convert chlorine compounds into ozone-destroying molecules. This ozone depletion in the tropical region exceeds that of previous eruptions, underlining the exceptional nature of the Hunga Tonga eruption.

DOI : https://doi.org/10.1126/science.adg2551

LACy/OSU-R Scientific contact : Stéphanie Evan, LACy (stephanie.evan@univ-reunion.fr)

Rapid ozone destruction following the eruption of Hunga Tonga: Following the eruption of Hunga Tonga, a measurement campaign using meteorological balloon instruments took place at the Maïdo observatory (photo left). The plume dynamics highlighted the volcanic injection of water vapor (H2O), sulfur dioxide (SO2) and hydrogen chloride (HCl), promoting rapid conversion of chlorine compounds to chlorine molecules at the surface of hydrated volcanic aerosols, and ozone depletion in the stratosphere. The ozone profile for January 22, 2022 (black line) contrasts with the climatology of La Réunion (red line), showing a marked decline.