Comment on egusphere-2025-6226

<strong class="journal-contentHeaderColor">Abstract.</strong> The explosive eruption of Hunga Tonga-Hunga Ha'apai (HTHH) in January 2022 marked a historic event as one of the largest volcanic explosions in the past 140 years. Unlike typical volcanic eruptions, which primarily inject sulfur dioxide (SO₂), HTHH introduced a massive plume of marine water vapor up to an altitude of ~57 km, reaching the mesosphere. In this study, we use balloon-borne measurements to investigate the optical, microphysical and chemical properties of the HTHH aerosol plume eight months after the eruption. The peak concentration of the Hunga plume located between 20.5&ndash;23 km was near 8&ndash;9 #/cm³ for aerosol diameter greater than 0.3&micro;m and Scattering Ratio at 940 nm near 4&ndash;5. Our balloon-based sampling and ion chromatographic analysis revealed the presence of key ions such as Na⁺, K⁺, NH₄⁺, Ca&sup2;⁺, Cl⁻, and traces of SO₄&sup2;⁻ in the samples collected in the lower part of the HTHH plume. These findings suggest a substantial contribution of marine aerosols to the stratospheric aerosol burden. The results suggest that the interaction between volcanic ash, water vapor, and marine aerosols led to unique chemical processes, which significantly influenced the composition and behavior of the stratospheric aerosol layer.