Impacts of the Hunga Tonga-Hunga Ha'apai Eruption: Insights from the SOCOLv4 ESM about past and future

We utilized the Earth System model SOCOLv4 to assess the impacts of the Hunga Tonga-Hunga Ha’apai eruption comprehensively. To accurately estimate the model's performance in terms of water vapour and aerosol plume transport during the initial year, we conducted a multi-member ensemble of free-running simulations and additional simulations employing atmospheric dynamics specified to the ERA5 reanalysis data. These simulations were compared with satellite and reanalysis products. The free-running ensemble simulations with only SO2 (no additional H2O) emissions showed the importance of the two species interaction for the resulting sulphate aerosol evolution, in agreement with previous studies. Furthermore, our primary free-running ensemble simulations, comparing scenarios with and without the eruption event, unravelled a negative response in polar stratospheric ozone levels and temperature. Importantly, these changes were found to be coupled to polar vortex dynamics confirming a larger ozone hole during the austral winter and spring of 2023.