The environmental impact of the Puyehue–Cordon Caulle 2011 volcanic eruption on Buenos Aires

G B Raga,B Kucienska,M Torres Brizuela,D Baumgardner,A G Ulke

doi:10.5194/nhess-13-2319-2013

Abstract

Abstract. On 4 June 2011, the volcanic complex Puyehue–Cordon Caulle located in the Chilean Andes erupted, producing a plume of gases and particles that eventually circled the Southern Hemisphere, disrupting air travel and depositing ash in large quantities. On eight occasions, the plume passed over the city of Buenos Aires, Argentina, leading local authorities to close the two international airports. The eruption occurred during an on-going field campaign when measurements of the properties of atmospheric aerosol particles were being made in Buenos Aires as part of a year-long study of the concentration and optical properties of aerosol at one site in the city. The suite of instruments deployed in Buenos Aires were not tailored to measurements of volcanic ash, but were designed to characterize urban conditions. Nevertheless, these measurements were analysed for periods when vertical profiles of aerosol backscatter, made with a ceilometer, clearly showed the presence of the volcano plume over the research site and resulted in airport closure. Aerosol optical thickness derived from AERONET, MODIS and a ceilometer at our research site, all show enhanced values clearly indicating that the three platforms identified the volcanic plume simultaneously. However, a quantitative comparison of the different estimates proves difficult, suggesting large spatial and temporal variability of the plume. Our results indicate that the number concentration of condensation nuclei (CN), the mass concentration of particle-bound polycyclic aromatic hydrocarbons (PPAH) and the light absorption coefficient exceeded the average background values by more than one standard deviation during the events of volcanic plume. The anomalous concentrations of CN suggest new particle formation, presumably from the conversion of SO2, while the anomalous concentrations of PPAH may come from the uptake of PAHs on the plume particles or from chemical reactions on the surface of plume particles. The anomalous absorption coefficients indicate that plume particles may contain certain compounds that can absorb radiation at 550 nm. Another possible explanation consistent with the observations is the scavenging of black carbon from urban sources as the plume descends through the boundary layer to the surface. In addition, the volcanic plume influenced the local meteorology resulting in a decrease of the temperature when compared to the average temperature during days with no plume present.

Highlights

The volcanic complex Puyehue–Cordon Caulle in the Chilean southern Andes erupted at 14:45 local time (LT) on 4 June 2011 (SERNAGEOMIN, 2011) from a new vent (“We Pillán” located 7 km NNW of the crater of the Puyehue volcano, Collini et al, 2013) of the Cordon Caulle complex, located in the southern Andes volcanic zone (SAVZ) at 40.58◦ S and 72.13◦ W, and 2240 m above mean sea level (a.m.s.l.)
Our results indicate that the number concentration of condensation nuclei (CN), the mass concentration of particlebound polycyclic aromatic hydrocarbons (PPAH) and the light absorption coefficient exceeded the average background values by more than one standard deviation during the events of volcanic plume
This wavelength is closest to the 530 nm wavelength used by the particle soot absorption photometer (PSAP) and nephelometer and the 550 nm wavelength used by the Moderate Resolution Imaging Spectroradiometer (MODIS) that is carried on the Aqua (Parkinson, 2003) and Terra satellites and whose data we used to evaluate the aerosol optical thickness (AOT)

Summary

Introduction

The volcanic complex Puyehue–Cordon Caulle in the Chilean southern Andes erupted at 14:45 local time (LT) on 4 June 2011 (SERNAGEOMIN, 2011) from a new vent (“We Pillán” located 7 km NNW of the crater of the Puyehue volcano, Collini et al, 2013) of the Cordon Caulle complex, located in the southern Andes volcanic zone (SAVZ) at 40.58◦ S and 72.13◦ W, and 2240 m above mean sea level (a.m.s.l.). Raga et al.: Impact of Puyehue–Cordon Caule 2011 eruption produced a large plume of gas and ash particles that reached 10 km above crater rim level and that eventually circled the Southern Hemisphere disrupting air travel on several continents. Thousands of sheep eventually died of starvation due to the heavy layer of ash that covered and killed the vegetation that they consume. This complex had previously erupted 51 yr earlier, on 24 May 1960, following the Mw 9.5 great Chilean earthquake about 240 km to the west (Lara et al, 2004). This complex had previously erupted 51 yr earlier, on 24 May 1960, following the Mw 9.5 great Chilean earthquake about 240 km to the west (Lara et al, 2004). Gerlach et al (1988) and Lara et al (2006) presented a summary of recent eruptions of this volcanic complex, while Singer et al (2008) presented its long-term history

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