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AEROIASI-Sulphate AOD (a) and altitude of the aerosol extinction coefficient profile maximum (d); IASI-SO2 Oxford SO2 column amount (b) and altitude of the partial column profile maximum (e); CHIMERE SO2 column amount (c) and altitude of the concentration profile maximum (f), for IASI daytime overpass on 19 March 2012.
Source publication
We developed a new retrieval algorithm based on the Infrared Atmospheric Sounding Interferometer (IASI) observations, called AEROIASI-Sulphates, to measure vertically-resolved sulphate aerosols (SA) extinction and mass concentration profiles, with limited theoretical uncertainties (typically ~25 % total uncertainty for SA mass column estimations)....
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Citations
... According to Bourassa et al. (2012), this eruption was the largest source of SO 2 emissions in the 2002-2012 time period. Data from the eruption of Mount Etna on 19 March 2012 in Sicily showed that sulfate aerosols were at a height between 6 and 7 km and 10-12 km (Guermazi et al., 2019). ...
The eruption of the Cumbre Vieja volcano on the island of La Palma (Canary Islands, Spain) began on September 19, 2021 and ended on December 13, 2021. It lasted continuously for 85 days with short periods of calm when lava did not exit the cone of the volcano. Vast amounts of volcanic material, including ash and gases, were emitted into the environment. This research focuses on these emissions. The main objective is to use available open-source data to examine the impact on regional and local air quality. Data from the following sources were used: 1) Copernicus Atmosphere Monitoring Service (CAMS) data was used to track the transfer of volcanic SO2 in the troposphere in early October over long distances from the source of the eruption, including Western and Eastern Europe, across the Atlantic Ocean and the Caribbean; 2) Data from ground monitoring stations measured the concentrations of SO2 and PM10 near the source; 3) AErosol RObotic NETwork (AERONET) data from the La Palma station that showed high Aerosol Optical Depth (AOD) values (over 0.4) during the active phase of emissions on September 24 and 28, as well as on October 3; 4) Ångström Exponent (AE) values indicated the presence of particles of different sizes. On September 24, high AE values (>1.5), showed the presence of fine-mode fraction scattering aerosols such as sulfates; 5) Cloud Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) data additionally confirmed the presence of sulfate and dust aerosols in the atmosphere over the region. However, the influence of Saharan dust on the atmosphere of the entire region could not be excluded. This research helps forecast air pollution resulting from large-scale volcanic eruptions and associated health risks to humans.
... Moreover, Mount Etna's volcanic activity is monitored continuously to estimate SO 2 fluxes and plume injection heights (Salerno et al., 2009;Mastin et al., 2009;Sellitto et al., 2016;Salerno et al., 2018). Volcanic gases and aerosols are also subject to numerous physical and chemical evolution processes, such as sulfate production or cloud condensation nuclei activation, which have been recently studied (Sellitto et al., 2017;Guermazi et al., 2019;Pianezze et al., 2019) but are not accounted for in this study. ...
... In the IASI dataset, a bimodal altitude distribution is observed, indicating the coexistence of two separate subplumes during this eruption: one located to the east at higher altitude and another located to the west at lower altitude (Fig. 2). This has also been observed in "AEROIASI-Sulphates" soundings in Sellitto et al. (2017) and Guermazi et al. (2019). This partition is due to the sharp separation between emissions at very high altitudes ( 12 km) and emis-sions below 7.5 km (Table 2) and to the fact that at the Mount Etna latitudinal wind shear is generally strong with steady westerly winds in the higher troposphere and more variable winds in the lower troposphere. ...
Excessive numerical diffusion is one of the major limitations in the representation of long-range transport by chemistry transport models. In the present study, we focus on excessive diffusion in the vertical direction, which has been shown to be a major issue, and we explore three possible ways of addressing this problem: increasing the vertical resolution, using an advection scheme with anti-diffusive properties and more accurately representing the vertical wind. This study was carried out using the CHIMERE chemistry transport model for the 18 March 2012 eruption of Mount Etna, which released about 3 kt of sulfur dioxide into the atmosphere in a plume that was observed by satellite instruments (the Infrared Atmospheric Sounding Interferometer instrument, IASI, and the Ozone Monitoring Instrument, OMI) for several days. The change from the classical scheme to the anti-diffusive scheme in the vertical direction was shown to provide the largest improvement to model outputs in terms of preserving the thin plume emitted by the volcano. To a lesser extent, the improved representation of the vertical wind field was also shown to reduce plume dispersion. Both of these changes helped to reduce vertical diffusion in the model as much as a brute-force approach (increasing vertical resolution).
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 [Formula: see text] 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 [Formula: see text] and [Formula: see text], at TOA and surface, are found at a fixed location [Formula: see text] downwind the degassing craters. This is the first available estimation in the literature of the local radiative impact of a passive degassing volcanic plume.
