Understanding the impact of Hunga-Tonga undersea eruption on the stratospheric aerosol population using Balloon measurements, Satellite data, and model simulations

<p>The stratospheric aerosol layer has witnessed large perturbations in the last couple of years. From extreme wildfires in North America and Australia to medium-size volcanic eruptions like Ambae, in July 2018, Raikoke, in 2019, and finally the Hunga-Tonga Ha&#8217;apai in January 2022. Reported as the largest marine eruption ever recorded, researchers used Microwave Limb Sounder (MLS) satellite data to reveal that this volcano injected the equivalent of 10% of the total stratospheric water vapor content (100 Tg) into the stratosphere. As a consequence, increased OH radicals from water vapor were reported to further reduce the SO₂lifetime by 50%.</p> <p>Here we outline the ionic composition, in parallel with microphysical, chemical, and optical properties of stratospheric aerosols using balloon measurements from Brazil 5-7 months after the eruption, in comparison with satellite data and model simulations. Cloud-Aerosol Lidar and Infrared Pathfinder&#160;<em>Satellite</em>&#160;Observation (CALIPSO) and ground-based lidar measurements revealed the existence of a volcanic plume between 20 and 25 km. Particle size information derived from balloon-borne optical counters showed the presence of aerosols with a size radius >0.3&#181;m and their subsequent sedimentation. In addition, ion chromatographic analysis of samples collected within the plume using a light-weight aerosol sampler revealed the presence of ammonia (0.3 ng/m³), sulfate (0.4 ng/m³), nitrate (1 ng/m³), and nitrite (1 ng/m³) in addition to Potassium (0.14 ng/m³), magnesium (0.12 ng/m³), and calcium (0.2 ng/m³). One of the striking findings of our measurements was the existence of traces of Dimethylamine (DMA) in our flights alongside the above-mentioned ionic components. DMA is known to enhance new particle formation upon reacting with H₂SO₄ and could have played an important role in the volcanic plume microphysical evolution. Although satellite data have revealed the presence of SO₂ it is still uncertain if the SO₂ only evolved from the Hunga-Tonga itself or as a consequence of a marine eruption that could have emitted Dimethylsulfuroxide (DMSO) into the stratosphere resulting in sulfate production.</p> <p>&#160;</p> <p>&#160;</p>