The 2022 Hunga eruption injected an unprecedented 150 Tg of water vapor into the stratosphere, accelerating SO2 oxidation and sulfate aerosol formation. Despite releasing less ash than previous eruptions of similar magnitude, the role of ash in the early plume and its rapid removal remain unclear. We performed experiments with the ICOsahedral Nonhydrostatic model with Aerosols and Reactive Trace gases (ICON-ART) to better understand the role of water vapor, SO2 and ash emissions, the aerosol–radiation interaction, and aerosol dynamical processes (nucleation, condensation, and coagulation) in the Hunga plume in the first week after the eruption. Furthermore, we compared our results with satellite observations to validate SO2 oxidation and aerosol dynamical processes. Our results show that about 1.2 Tg of SO2 emission, along with water vapor emission, is necessary to explain both the SO2 column loadings and sulfate aerosol optical depth during the first week after the eruption. Although the model reproduces the development of SO2 and sulfate aerosols well, the aerosol dynamics alone cannot explain the ash removal after the eruption, as was seen in satellite images. However, some of the ash might not be detected due to the exceptionally strong coating of the ash particles. Both the strong coating and a doubling of the sulfate effective radii within 1 week occur only when water vapor emission is included in the chemistry. Furthermore, the aerosol–radiation interaction warms the plume and reduces or, depending on the experiment, even reverses the descent of the water vapor plume that would otherwise occur due to radiative cooling.</p
