Long-range transport of stratospheric aerosols in the Southern Hemisphere following the 2015 Calbuco eruption

Abstract

Abstract. After 43 years of inactivity, the Calbuco volcano, which is located in the southern part of Chile, erupted on 22 April 2015. The space-time evolutions (distribution and transport) of its aerosol plume are investigated by combining satellite (CALIOP, IASI, OMPS), in situ aerosol counting (LOAC OPC) and lidar observations, and the MIMOSA advection model. The Calbuco aerosol plume reached the Indian Ocean 1 week after the eruption. Over the Reunion Island site (21 • S, 55.5 • E), the aerosol signal was unambiguously enhanced in comparison with "background" conditions, with a volcanic aerosol layer extending from 18 to 21 km during the May-July period. All the data reveal an increase by a factor of ∼ 2 in the SAOD (stratospheric aerosol optical depth) with respect to values observed before the eruption. The aerosol mass e-folding time is approximately 90 days, which is rather close to the value (∼ 80 days) reported for the Sarychev eruption. Microphysical measurements obtained before, during, and after the eruption reflecting the impact of the Calbuco eruption on the lower stratospheric aerosol content have been analyzed over the Reunion Island site. During the passage of the plume, the volcanic aerosol was characterized by an effective radius of 0.16 ± 0.02 µm with a unimodal size distribution for particles above 0.2 µm in diameter. Particle concentrations for sizes larger than 1 µm are too low to be properly detected by the LOAC OPC. The aerosol number concentration was ∼ 20 times higher that observed before and 1 year after the eruption. According to OMPS and lidar observations, a tendency toward conditions before the eruption was observed by April 2016. The volcanic aerosol plume is advected eastward in the Southern Hemisphere and its latitudinal extent is clearly bounded by the subtropical barrier and the polar vortex. The transient behavior of the aerosol layers observed above Reunion Island between May and July 2015 reflects an inhomogeneous spatio-temporal distribution of the plume, which is controlled by the localization of these dynamical barriers.

Stratospheric Aerosols, Polar Stratospheric Clouds, and Polar Ozone Depletion After the Mount Calbuco Eruption in 2015

“…This is also seen in the OSIRIS data and modeled results, but the extinction of OMPS (Figure a) is about half of the HalfSO2 case value (Figure e) and a third of the Base case value (Figure c) near 50°S and 15 km altitude. We note that Bègue et al () show the OMPS extinction compares reasonable well with ground lidar results, but they use the OMPS version 0.5 aerosol product, while we use the version 1 product in this paper.…”

“…After the Mount Calbuco eruption, Light Optical Aerosol Counter (LOAC) systems (Bègue et al, ; Renard et al, , ) were launched with latex weather balloons at the Reunion Island site (21°S, 55°E) on 19 May and 19 August 2015. Through the measurements of the light scattered by particles at two specific angles (Lurton et al, ), the LOAC provides aerosol concentrations for 19 size classes ranging from 0.2 to 50 μm in diameter with a vertical profile from near the surface to over 30 km.…”

“…For this study, we investigate the impact of the Mount Calbuco eruption on the stratospheric sulfate aerosol and on the Antarctic ozone hole of 2015. Mount Calbuco, located in Chile at 41°S and 73°W, erupted several times in April 2015 and emitted ~0.4 Tg of SO 2 into the atmosphere as high as 21 km (Bègue et al, ; Mills et al, ; Solomon et al, ). Satellite observations (discussed in section ) show the volcanic sulfate aerosol extended past the tip of South America, and remained abundant in October of 2015 when the ozone hole typically forms.…”

Analysis of a southern sub-polar short-term ozone variation event using a millimetre-wave radiometer

“…When the intrusion of air from the polar vortex reaches mid-latitudes and produces ozone decreases, it induces anomalies on the surface UV radiation. Bittencourt et al (2018) also linked the occurrence of this event over South America to later changes in the tropospheric and stratospheric dynamic behaviour. Thus, this parameter can be used to study the dynamics of the Antarctic polar vortex and as a tracer of poorozone air masses that are released from the AOH Kirchhoff et al, 1996;Pinheiro et al, 2011;Wolfram et al, 2012;Hauchecorne et al, 2002;Marchand et al, 2005;Bencherif et al, 2007).…”

“…The accuracy of the model has been evaluated by Hauchecorne et al (2002) and validated against airborne lidar ozone measurements using a correlation between PV and ozone (Heese et al, 2001;Godin et al, 2002;Jumelet et al, 2009). The ability of the MIMOSA model to determine the origin of air masses influencing a given site has been highlighted in several studies Jumelet et al, 2009;Bègue et al, 2017). Moreover, the MIMOSA model is frequently used to detect the origin of air masses inducing laminae on ozone profiles Godin et al, 2002;Portafaix et al, 2003).…”