Abstract
Abstract. The eruption in June 2011 of the Puyehue-Cordón Caulle Volcanic Complex in Chile impacted air traffic around the Southern Hemisphere for several months after the initial ash emissions. The ash deposited in vast areas of the Patagonian Steppe was subjected to the strong wind conditions prevalent during the austral winter and spring experiencing resuspension over various regions of Argentina. In this study we analyze the meteorological conditions that led to the episode of volcanic ash resuspension which impacted the city of Buenos Aires and resulted in the closure of the two main airports in Buenos Aires area (Ezeiza and Aeroparque) on 16 October 2011. A relevant result is that resuspended material (volcanic ash plus dust) imprints a distinguishable feature within the atmospheric thermodynamic vertical profiles. The thermodynamic soundings show the signature of "pulses of drying" in layers associated with the presence of hygroscopic ash in the atmosphere that has already been reported in similar episodes after volcanic eruptions in other parts of the world. This particular footprint can be used to detect the probable existence of volcanic ash layers. This study also illustrates the utility of ceilometers to detect not only cloud base at airports but also volcanic ash plumes at the boundary layer and up to 7 km altitude. Aerosol properties measured in the city during the resuspension episode indicate the presence of enhanced concentrations of aerosol particles in the boundary layer along with spectral signatures in the measurements at the Buenos Aires AERONET site typical of ash plus dust advected towards the city. The mandatory aviation reports from the National Weather Service about airborne and deposited volcanic ash at the airport near the measurement site (Aeroparque) correlate in time with the enhanced concentrations. The presence of the resuspended material was detected by the CALIOP lidar overpassing the region. Since the dynamics of ash resuspension and recirculation are similar to the dynamics of dust storms, we use the HYSPLIT model with the dust storm module to simulate the episode that affected Buenos Aires. The results of the modeling agree qualitatively with satellite lidar measurements.
Highlights
At the end of April 2011, dozens of volcano-tectonic earthquakes mostly located at the Puyehue-Cordón Caulle Volcanic Complex (PCCVC: 40.59◦ S, 72.117◦ W; 2236 m a.s.l.) in the Chilean Southern Andes were detected by the Observatorio Volcanológico de Los Andes del Sur dependent of Servicio Nacional de Geología y Minería (SERNAGEOMIN), which is the Chilean agency for geology and mining policies that monitors the volcanic activity and reports the level alerts
Events of resuspension of volcanic ash are dynamically similar to dust storms, so the lifting and subsequent advection of the ash particles can be simulated using the dust emission algorithm included in the current public version of Hybrid SingleParticle Lagrangian Integrated Trajectory (HYSPLIT), which has been previously evaluated for several windblown dust emissions (Draxler et al, 2001; Stein et al, 2015)
The simulations with the HYSPLIT model captured the resuspension episode and the ash plus dust plume timing and location after the surface soil type appropriate for the Patagonian Steppe had been incorporated in the model
Summary
At the end of April 2011, dozens of volcano-tectonic earthquakes mostly located at the Puyehue-Cordón Caulle Volcanic Complex (PCCVC: 40.59◦ S, 72.117◦ W; 2236 m a.s.l.) in the Chilean Southern Andes were detected by the Observatorio Volcanológico de Los Andes del Sur dependent of Servicio Nacional de Geología y Minería (SERNAGEOMIN), which is the Chilean agency for geology and mining policies that monitors the volcanic activity and reports the level alerts. The PCCVC volcanic activity declined until March 2012, when the red alert level was downgraded to orange and was subsequently switched to yellow on 24 April 2012. This status alert remained until August 2012, when the alert level was set to green. A detailed chronological description of the volcanic eruption and a modeling of the volcanic ash dispersion during the main phase explosive events are reported by Collini et al (2013). The determination of physical parameters during the main eruptive phase in relationship with the eruption classification and the characterization of the plume dynamics and spreading is conducted by Bonadonna et al (2015b)
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