3-D Numerical Modeling Perspectives on Lightning Generation in Volcanic Eruption Clouds

Friday, 19 December 2014: 4:00 PM
Alexa R Van Eaton, Arizona State University, School of Earth and Space Exploration, Tempe, AZ, United States; USGS Cascades Volcano Observatory, Vancouver, WA, United States, Sonja A Behnke, University of South Florida Tampa, Tampa, FL, United States and Michael Herzog, University of Cambridge, Cambridge, United Kingdom
Although numerous charging mechanisms have been implicated in the formation of volcanic lightning, recent insights from lightning mapping arrays indicate that vent charging (produced at or near the volcanic source) creates electrical discharges that are distinct from lightning initiated in the airborne plume during transport away from the vent. Previous work has suggested that turbulent structure and formation of hydrometeors, including rain, graupel and ash aggregates, are likely to play important roles in the plume charging process. We examine these phenomena with 3D large-eddy simulations of volcanic plume development that include cloud microphysics, using the Active Tracer High-resolution Atmospheric Model (ATHAM). Three relatively recent eruptions are targeted, each with different plume heights, degrees of wind interaction, and amounts of surface water interaction. We have compared the simulated evolution of turbulence and precipitation formation with data from lightning mapping arrays to address the following question – what can lightning tell us about the initiation and development of a volcanic plume in near-real time?