Modeling volcanic ash resuspension – application to the 14–18 October 2011 outbreak episode in central Patagonia, Argentina

Abstract

Abstract. Volcanic fallout deposits from the June 2011Cordón Caulle eruption on central Patagonia were remobilized in several occasions months after their emplacement. In particular, during 14-18 October 2011, an intense outbreak episode generated widespread volcanic clouds that were dispersed across Argentina, causing multiple impacts in the environment, affecting the air quality and disrupting airports. Fine ash particles in volcanic fallout deposits can be resuspended under favorable meteorological conditions, particularly during strong wind episodes in arid environments with low soil moisture and poor vegetation coverage. As opposed to eruption-formed ash clouds, modeling of resuspensionformed ash clouds has received little attention. In consequence, there are no emission schemes specially developed and calibrated for resuspended volcanic ash, and few operational products exists to model and forecast the formation and dispersal of resuspension ash clouds. Here we implement three dust emission schemes of increasing complexity in the FALL3D tephra dispersal model and use the 14-18 October 2011 outbreak episode as a model test case. We calibrate the emission schemes and validate the results of the coupled WRF-ARW (Weather Research and ForecastingAdvanced Research WRF)/FALL3D modeling system using satellite imagery and measurements of visibility (a quantity related to total suspended particle concentration at the surface) and particulate matter (PM 10 ) concentration at several meteorological and air quality stations located at Argentina and Uruguay. Our final goal is to test the capability of the modeling system to become, in the near future, an operational forecast product for volcanic ash resuspension events.

Statistical analysis of dispersal and deposition patterns of volcanic emissions from Mt. Sakurajima, Japan

“…On the other hand, airborne volcanic ash was distributed evenly across the area surrounding the volcano, seen as an average increase in the SPM concentrations. Considering that fine volcanic ash can stay airborne for extended periods and that unconsolidated light ash can be recirculated (Folch et al, 2014), this would indicate that once released from the volcano, fine ash emissions are caught within localised circulations and diffused across the surrounding area, increasing the associated health hazards (Lähde et al, 2013). This is also reflected in the ashfall deposition values, as a background value of ∼ 1-10 g m −2 mo −1 was also seen independently of the season and dominant wind patterns.…”

Numerical simulations of windblown dust over complex terrain: the Fiambalá Basin episode in June 2015

“…The Fall3D model in resuspension mode (Folch et al, 2014) includes three different emission schemes (of increasing sophistication) that are applied to the case of volcanic ash, although they have been developed theoretically or calibrated experimentally for mineral dust: (i) Westphal scheme (Westphal et al, 1987), (ii) Marticorena and Bergametti scheme (Marticorena and Bergametti, 1995;Marticorena et al, 1997), and (iii) Shao scheme (Shao et al, 1993;Shao and Leslie, 1997;Shao and Lu, 2000).…”

“…In this work, we use the Shao scheme as is described by Folch et al (2014) with minor modifications. The theory for dust emission by Shao et al (1993) is based on a hypothesis about the energetics of dust emission and considers particle-particle interaction by saltation bombardment (see Folch et al, 2014, for more details).…”

“…The theory for dust emission by Shao et al (1993) is based on a hypothesis about the energetics of dust emission and considers particle-particle interaction by saltation bombardment (see Folch et al, 2014, for more details). This parametrization depends crucially on deposit characteristics such as particle size distribution, thickness, and particle density and requires reliable input data.…”

“…However, studies focused on the performance of dispersion models simulating concentrations of windblown dust in South America are scarce (e.g., Johnson et al, 2010;Gaiero et al, 2013). For example, events of volcanic ash resuspension in Patagonia were recently simulated using the WRF-ARW/FALL3D modeling system with promising results (Folch et al, 2014;Reckziegel et al, 2016). Dust models simulate the main processes of the dust cycle: emission, transport, and deposition (Tegen, 2003).…”