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

A. Folch,E. Collini,M. S. Osores,L. Mingari

doi:10.5194/nhess-14-119-2014

Abstract

Abstract. Volcanic fallout deposits from the June 2011 Cordón 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 resuspension-formed 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 Forecasting – Advanced 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 (PM10) 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.

Highlights

Resuspension and dispersal of volcanic ash by wind is of concern to human health and the environment (Baxter, 1999; Wilson et al, 2012)
The ash emission schemes in FALL3D7.0 assume that the resuspended ash is distributed uniformly along the vertical up to a maximum height fixed by the user bands
Given the reverse absorption of volcanic ash particles, the technique allows for discrimination between meteorological and volcanic ash clouds

Summary

Introduction

Resuspension and dispersal of volcanic ash by wind is of concern to human health and the environment (Baxter, 1999; Wilson et al, 2012). Other hazards include disruption to ground transportation systems and airports (see Guffanti et al, 2009). All these impacts can occur far away from the original deposit region because, like dust clouds, resuspended ash clouds can be dispersed over large distances. Favorable meteorological conditions occurred during 20–21 September 2003 resulted in continuous resuspension of relic volcanic ash from the Katmai volcano and the formation of ash clouds that were transported up to 230 km into the Gulf of Alaska, affecting operations at the Kodiak Airport (Hadley et al, 2004).

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Conclusion