Abstract
Abstract. This study investigates the influence of the 2015 Calbuco eruption (41.2∘ S, 72.4∘ W; Chile) on the total columnar aerosol optical properties over the Southern Hemisphere. The well-known technic of sun photometry was applied for the investigation of the transport and spatio-temporal evolution of the optical properties of the volcanic plume. The CIMEL sun photometer measurements performed at six South American and three African sites were statistically analysed. This study involves the use of the satellite observations and a back-trajectory model. The passage of the Calbuco plume is statistically detectable in the aerosol optical depth (AOD) observations obtained from sun photometer and MODIS observations. This statistical detection confirms that the majority of the plume was transported over the northeastern parts of South America and reached the South African region 1 week after the eruption. The plume impacted the southern parts of South America to a lesser extent. The highest AOD anomalies were observed over the northeastern parts of South America. Over the South African sites, the AOD anomalies induced by the spread of the plume were quite homogeneously distributed between the east and west coasts. The optical characteristics of the plume near the source region were consistent with an ash-bearing plume. Conversely, sites further from the Calbuco volcano were influenced by ash-free plume. The optical properties discussed in this paper will be used as inputs for numerical models for further investigation of the ageing of the Calbuco plume in a forthcoming study.
Highlights
Given that major volcanic eruptions have the potential to inject large amounts of sulfur into the stratosphere, they are considered to be one of the main sources of stratospheric sulfur (Carn et al, 2015; Thomason et al, 2007)
The influence of the Calbuco eruption on the total columnar aerosol optical properties in the Southern Hemisphere has been presented in this investigation
The study mainly focuses on the analysis of the sun photometer measurements performed at six South American and three African sites
Summary
Given that major volcanic eruptions have the potential to inject large amounts of sulfur into the stratosphere, they are considered to be one of the main sources of stratospheric sulfur (Carn et al, 2015; Thomason et al, 2007). Sulfate aerosols are formed in the volcanic plume by the aqueous and gaseous oxidation of sulfur dioxide (SO2) and the subsequent nucleation and accumulation of particles and droplets (Watson and Oppenheimer, 2000). Volcanic emissions may have a significant impact on the atmospheric composition and radiative budget (McCormick et al, 1995; Solomon et al, 1999, 2011). N. Bègue et al.: Long-range transport of the 2015 Calbuco volcanic plume can lead to significant warming of the middle atmosphere. Using ground-based and satellite observations, various studies have shown that a significant ozone loss occurs following a major volcanic eruption (Hofmann and Oltmans, 1993; Solomon et al, 2005). The sulfate aerosols formed following these events provide surfaces for heterogeneous chemical reactions, which lead to ozone depletion (Tie and Brasseur, 1995; Solomon et al, 1996; Bekki et al, 1997)
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