Ash and Ice Aggregation in Satellite Retrieval: The 15 January 2022 Hunga Tonga‐Hunga Ha'apai Hydromagmatic Eruption

Volcanic eruptions represent one of the most impressive and hazardous natural phenomena on our planet. Violent volcanic eruptions can inject in the atmosphere a huge amount of materials, from gases to ash particles. Finer ash particles remain suspended in the atmosphere for long time, even weeks, and represent a fatal risk for aviation. The work is part of the studies involved in volcanic hazard mitigation by means of satellite observations. Volcanic clouds, formed during eruptions, can be water-enriched. Water particles can mask the presence of ash particles, intensifying the volcanic hazard. We focus our analysis on the 15 January 2022 Hunga Tonga eruption, where we estimate the altitude of the two formed volcanic clouds. We also study how the fine ash (<64 μm diameter) total mass in atmosphere varies depending on the assumed fraction of ash/ice in an aggregate. Estimating the exact amount of erupted fine ash mass is challenging, mainly in presence of water-enriched volcanic clouds. Further works should investigate aggregates where the ice fraction is higher than the ash fraction.