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

Pasquale Sellitto (1) , Giuseppe Salerno , Alessandro La Spina (2) , Tommaso Caltabiano (2) , Simona Scollo (2) , Antonella Boselli (3) , Giuseppe Leto , Ricardo Zanmar Sanchez , Alessia Sannino , Suzanne Crumeyrolle (4) , Benjamin Hanoune (5) , Chiara Giorio (6) , Salvatore Giammanco , Tjarda Roberts (7) , Alcide Di Sarra (8) , Bernard Legras (9) , Pierre Briole (10)

1 LISA (UMR_7583) - Laboratoire Interuniversitaire des Systèmes Atmosphériques
2 INGV - Istituto Nazionale di Geofisica e Vulcanologia - Sezione di Catania
3 IMAA - Istituto di Metodologie per l'Analisi Ambientale
4 LOA - Laboratoire d’Optique Atmosphérique - UMR 8518
5 PC2A - Physicochimie des Processus de Combustion et de l’Atmosphère - UMR 8522
6 Department of Chemistry (Cambridge]
7 LPC2E - Laboratoire de Physique et Chimie de l'Environnement et de l'Espace
8 ENEA - Italian National agency for new technologies, Energy and sustainable economic development [Frascati]
9 LMD - Laboratoire de Météorologie Dynamique (UMR 8539)
10 IPGP (UMR_7154) - Institut de Physique du Globe de Paris

<p>The aerosol properties of Mount Etna&#8217;s passive degassing plume and its short-term processes and radiative impact were studied in detail during the EPL-RADIO/REFLECT campaigns (summer 2016, 17 and 19), using a synergistic combination of remote-sensing and in situ observations, and radiative transfer modelling. Summit observations show extremely high particulate matter concentrations, with no evidence of secondary sulphate aerosols (SA) formation. Marked indications of secondary SA formation, i.e. by the conversion of volcanic SO2 emissions, are found at larger spatial scales (<20 km downwind craters). Using portable photometers, the first mapping of small-scale spatial variability of the average size and burden of volcanic aerosols is obtained, as well as different longitudinal, perpendicular and vertical sections. A substantial variability of the plume properties is found at these spatial scales, revealing that processes (e.g. new particle formation and coarse aerosols sedimentation) are at play, which are not represented with current regional scale modelling and satellite observations. 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 effects of the plume. Moreover, the radiative impact of Mount Etna&#8217;s emissions is studied using a medium-term time series (a few months during summer 2019) of coupled aerosol optical properties and surface radiative flux at a fixed station on Etna&#8217;s eastern flank. These are the first available estimations in the literature of the radiative impact of a passive degassing volcanic plume and are here critically discussed. Cases of co-existent volcanic aerosol layers and aerosols from other sources (Saharan dust transport events, wildfire from South Italy and marine aerosols) are also presented and discussed.</p>

Domains: Sciences of the Universe [physics]

Pasquale Sellitto, Giuseppe Salerno, Alessandro La Spina, Tommaso Caltabiano, Simona Scollo, et al.. Small-scale volcanic aerosols variability, processes and direct radiative impact at Mount Etna during the EPL-RADIO/REFLECT campaigns. EGU General Assembly 2020, May 2020, Vienne, Austria. ⟨10.5194/egusphere-egu2020-8337⟩. ⟨insu-02891851⟩