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The impact of ice particles in satellite thermal infrared fine ash estimates

Francesco Romeo1,2,4, Luigi Mereu3,4, Simona Scollo2

  • Affiliations: 1Department of Information Engineering, Electronics and Telecommunications, Sapienza University of Rome, Rome, Italy; 2Istituto Nazionale di Geofisica e Vulcanologia, Osservatorio Etneo, Catania, Italy; 3Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Bologna, Bologna, Italy; 4Centre of Excellence CETEMPS, University of L\'Aquila, L\'Aquila, Italy

  • Presentation type: Poster

  • Presentation time: Thursday 16:30 - 18:30, Room Poster Hall

  • Poster Board Number: 87

  • Programme No: 3.12.13

  • Theme 3 > Session 12

Abstract

Explosive eruptions inject a lot of volcanic particles, of different shapes and sizes, in the atmosphere. From lapilli, mainly responsible for tephra fallout in proximity of volcanoes, to fine ash particles (< 64 µm in diameter), responsible for potential damages to aircrafts due to a longer atmospheric residence time. Satellite thermal infrared (TIR) observations are an essential asset to monitor the dynamic and dispersion of these particles. Sometimes, ice enriched volcanic clouds can hide the presence of fine ash particles, intensifying the risks for the aviation. However, how ice particles affect the satellite retrievals is not investigated yet. In this work, we show how the fine ash total mass (FaTM) load in atmosphere varies depending on the ice fraction assumed in an aggregate. The 15 January 2022 Hunga Tonga-Hunga Ha'apai hydromagmatic eruption is used as case study. We assume three different levels of ice inclusions: 10%, 25% and 50% with a well mixing of these particles in the aggregate. We also consider two types of aggregate shapes: one spherical and less porous; one irregular more porous. We then use a radiative transfer model to simulate the radiance observed by a TIR passive radiometer, in presence of the assumed aggregates. We estimate the FaTM load by comparing the simulated radiances with the radiances observed by the TIR passive radiometer on board the GOES-17 satellite. The results show how FaTM load doubles in presence of spherical aggregates compared to irregular aggregates.