Researchers have developed an algorithm that can distinguish between volcanic and non–volcanic clouds using high-resolution satellite imagery. Called the Cloud Growth Anomaly (CGA) technique, the algorithm uses geostationary satellite data to detect fast growing vertical clouds caused by volcanic output. Volcanic ash produced by eruptions are a major threat to airplanes. In 2011, for example, Grímsvötn erupted, closing Iceland’s air space. Volcanic ash can cause significant damage to airplanes including in-flight engine failure. Researchers noted that “volcanic clouds produced by explosive eruptions can reach jet aircraft cruising altitudes in as little as 5 minutes.” Ten or more eruptions occur each year with a plume reach at or above jet cruising altitudes. Despite this threat, the authors of this study further note that “90% of the world’s volcanoes are not regularly monitored for activity.”
Geostationary weather satellites such as Himawari-8 and the GOES East and West satellites provide high resolution data that can be used to detect ash plumes. Currently, Volcanic Ash Advisory Centers (VAACs) tend to manually analyze satellite imagery due to limitations with discerning ash plumes from meteorological clouds using multispectral infrared-based techniques. In this latest study, the CGA technique uses infrared measurements on satellite imagery “to identify cloud objects and compute cloud vertical growth rates from two successive images” produced within 60 minutes of each other. The CGA method was applied to 79 different explosive volcanic events from 30 volcanoes between 2002 and 2017. The success rate of the CGA in correctly identifying ash clouds varied depending on whether it was applied to the latest generations weather satellites. On older satellites, the accuracy rate was about 55%. For new generation satellites such as Himawari-8, the accuracy rate rose to 90%.
The study (open access):
Pavolonis, M. J., Sieglaff, J., & Cintineo, J. 2018. Automated Detection of Explosive Volcanic Eruptions Using Satellite‐derived Cloud Vertical Growth Rates. Earth and Space Science.