Continent-Scale Low Frequency Lightning Remote Sensing

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This grant will support fundamental research that develops and applies new radio-based methods for detecting and measuring lightning discharges. Lightning causes substantial physical and economic damage every year; energetic lightning with high electric charge transfer has important practical consequences, such as forest fires and damage to structures. High impact lightning processes are not routinely measured. Energetic lightning flashes and meteorological conditions that create them are not well understood. Lightning also generates high energy radiation, but the specific process by which this occurs remains unknown. This project will develop new understanding of the conditions that produce these high impact phenomena and will deliver new tools for their improved detection and monitoring to help mitigate their impact. The research activities will involve students from under-represented groups and will enable innovative educational activities. Lightning remote sensing with low frequency electromagnetic fields is a powerful tool for probing and quantifying lightning processes from long distances and thus over a wide geographic area. This project has two main goals that build on low frequency lightning remote sensing techniques. First, a multi-sensor lightning charge moment change network will be resurrected, improved, and expanded; the network will deliver near real-time lightning impulse charge moment change measurements across the United States. This network will open the door to new scientific studies, such as the connection between thunderstorm structure and high charge transfer lightning, as well as deliver real-time guidance for researchers across the US who target measurements associated with energetic lightning, such as sprites. Second, detailed analysis of new and archived observations from an existing network of low frequency radio sensors across the globe will be mined for new datasets to improve our understanding of the mechanisms through which lightning generates high energy radiation in the form of terrestrial gamma-ray flashes. Detailed measurements of lightning current and charge motion before, during, and after terrestrial gamma-ray flashes will illuminate the physics behind their production and provide key experimental constraints on possible physical mechanisms.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.