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Unprecedented growth of volcanic aerosols in vorticized volcanic plume parts from 2019 Raikoke eruption (Kuril Islands)

Paul Ruyneau de Saint-George1, Marie Boichu1,2 , Joris Bonnat1, Raphael Grandin3, Philippe Goloub1

  • Affiliations: 1 Univ. Lille, Laboratoire d'Optique Atmosphérique (LOA), UMR 8518, Lille, France; 2 Centre National de la Recherche Scientifique, France; 3 Institut de Physique du Globe de Paris, Univ. Paris Cité, Paris, France 

  • Presentation type: Poster

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

  • Poster Board Number: 8

  • Programme No: 6.1.14

  • Theme 6 > Session 1

Abstract

The 2019 stratospheric eruption of Raikoke volcano had major impact on atmospheric composition and climate. The exact composition of Raikoke particles is still debated, especially in the long-lived, compact and vorticized plume parts, where ash and sulfate fractions are uncertain. The microphysical properties of volcanic particles, especially their size, are poorly known, whereas crucial for understanding their lifecycle and constraining climate models. The synergistic analysis of satellite (S5P/TROPOMI, MetOp/IASI) observations with ground-based photometric measurements (AERONET network) allowed us to provide novel information on particle sizes for aerosol typing. As shown recently for Hunga Tonga stratospheric particles (Boichu et al. 2023), when a plume overpasses a station, aerosol volume size distributions reflect a third mode that can be attributed to volcanic particles. In the vorticized plume parts, fine particle peak radii are shown to grow to 0.8-1 microns three months after the eruption. This is approximately thrice the size reached by the growing particles in the other non-vorticised plumes dispersed in the Northern hemisphere. Such different patterns support the growth of sulfate aerosols, which is heightened in the compact vorticised parts, likely resulting from increasing nucleation and coagulation in highly concentrated parcels. CALIOP data show a self-lofting of the vorticized plume parts from 14 km to 26 km in three months, with depolarization ratios decreasing from > 0.25 to < 0.01. High depolarizing properties that are rapidly lost may indicate the initial presence of fine ash particles rapidly coated by sulfate. Boichu et al 2023, DOI: 10.1029/2023JD039010