Spatial Analysis of Volcanic Lightning within Eruption Clouds
Abstract
Applications of volcanic lightning are advancing rapidly to detect and characterize explosive eruptions. Globally-detected volcanic lightning combined with plume modeling can help develop links between electrical phenomena and the eruptive processes that formed them, as well as the downwind transport of hazardous volcanic ash. In addition to ash charging, ice formation is a possible charging mechanism for eruption clouds. The June 2019 eruption of Raikoke volcano in the Kurile Islands of Russia, produced 11 distinct ash clouds in Himawari-8 satellite imagery, with 753 lightning strokes recorded by the Global Lightning Dataset (GLD360) lightning network. For 10 of the eruption clouds, most lightning occurred NW of the volcano (distances < 20 km), even though the eruption cloud traveled primarily East. The European Centre for Medium Range Weather Forecasts Re-Analysis (ERA-Interim) wind models during the eruption show low altitude (< 3km) winds blowing towards the NW. This may indicate that lightning NW of the vent was concentrated in the low altitude jet/column regions of the eruption cloud, or possibly in pyroclastic flows forming to the NW, rather than in the eastward-travelling buoyant umbrella region. Prior modeling of the 2009 Redoubt, AK eruption showed a positive relationship between lightning concentration and fallout of mixed ash and graupel (soft hail). Thus, the lightning may constrain where ash or graupel fallout is concentrated in an eruption column/cloud that is being affected by wind shear. In this study we use the 1D numerical plume model Plumeria, the ash dispersion model Ash3D, and spatial statistics to analyze the Raikoke eruption and determine how physical aspects of the eruption cloud influenced lighting locations. Initial Plumeria modeling indicates that in the largest pulse the eruption cloud (peak altitude ~16 km) temperature remained above -20 C (temperature where ice would be expected to form) until altitudes of ~10 km. This implies that ash charging rather than ice formation is the dominant method of charge generation for strokes that occurred NW of the volcano. We discuss how the spatial concentration of lightning used with plume models and atmospheric profiles may provide insights into the height, microphysical properties, and travel direction of eruption clouds in near real-time.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMV028.0014S
- Keywords:
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- 4314 Mathematical and computer modeling;
- NATURAL HAZARDS;
- 4336 Economic impacts of disasters;
- NATURAL HAZARDS;
- 8485 Remote sensing of volcanoes;
- VOLCANOLOGY;
- 8488 Volcanic hazards and risks;
- VOLCANOLOGY