Small-scale volcanic aerosols variability, processes and direct radiative impact at Mount Etna during the EPL-RADIO campaigns

• Published in: Scientific reports 2020-09, Vol.10 (1), p.15224-15224, Article 15224
• Main Authors: Sellitto, Pasquale, Salerno, Giuseppe, La Spina, Alessandro, Caltabiano, Tommaso, Scollo, Simona, Boselli, Antonella, Leto, Giuseppe, Zanmar Sanchez, Ricardo, Crumeyrolle, Suzanne, Hanoune, Benjamin, Briole, Pierre
• Format: Article
• Language: English
• Subjects: 639/33/445/209; 639/33/445/598; 639/624/1075/1078; 704/106/35/824; 704/172/4081; Aerosols; Breast cancer; Chemical Physics; Chemical Sciences; Degassing; Dietary intake; Fruits; Humanities and Social Sciences; Lidar; multidisciplinary; Optical analysis; or physical chemistry; Particulate matter; Photometers; Physics; Radiative transfer; Science; Science (multidisciplinary); Survival; Systematic review; Theoretical and; Vegetables
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-020-71635-1

The aerosol properties of Mount Etna’s passive degassing plume and its short-term processes and radiative impact were studied in detail during the EPL-RADIO campaigns (summer 2016–2017), using a synergistic combination of observations and radiative transfer modelling. Summit observations show extremely high particulate matter concentrations. Using portable photometers, the first mapping of small-scale (within ∼ 20 km from the degassing craters) spatial variability of the average size and coarse-to-fine burden proportion of volcanic aerosols is obtained. A substantial variability of the plume properties is found at these spatial scales, revealing that processes (e.g. new particle formation and/or coarse aerosols sedimentation) are at play, which are not represented with current regional scale modelling and satellite observations. Statistically significant progressively smaller particles and decreasing coarse-to-fine particles burden proportion are found along plume dispersion. Vertical structures of typical passive degassing plumes are also obtained using observations from a fixed LiDAR station constrained with quasi-simultaneous photometric observations. These observations are used as input to radiative transfer calculations, to obtain the shortwave top of the atmosphere (TOA) and surface radiative effect of the plume. For a plume with an ultraviolet aerosol optical depth of 0.12–0.14, daily average radiative forcings of - 4.5 and - 7.0 W/m 2 , at TOA and surface, are found at a fixed location ∼ 7 km downwind the degassing craters. This is the first available estimation in the literature of the local radiative impact of a passive degassing volcanic plume.