Advanced Spectrally-Resolved Plasma Diagnostics of Lightning

Lightning is a primary hazard to life and property from convective weather. The atmospheric electricity community has made strides in better understanding lightning, but the high energy and short time scale characteristics that make lightning a hazard also make it difficult to observe. This award will seek to answer questions about lightning using multiple techniques, including new and existing radio, optical, and X-ray sensors. The societal benefit of this work is in terms of improved understanding and detection of lightning, leading to increased public safety. A cohort of students will be involved in the research, allowing for training of the next generation of scientists. The primary objective of this project is to probe lightning and its fundamental physics with simultaneous multi-band sensors (radio + optical + X-rays). Radio sensors to be used include fast/slow electric field change antennas, and a 3D lightning mapping array. Optical instrumentation includes a photometer array, a high-speed camera and grism spectrometer, and a newly-developed instrument which leverages the emerging technology of neuromorphic sensors allowing for position-resolved, spectrally-resolved leader optical diagnostics. High energy measurements will be made by an X-ray scintillation detector and a gamma-ray detector. Observations will be performed at the New Mexico Langmuir Laboratory mountaintop facility, addressing the following research questions: 1) What are the dominant characteristics of stepped and dart leaders that result in completely different runaway electron acceleration mechanisms? What insights into this question can be gained from optical observations? 2) Is it possible to confidently measure the lightning channel temperature via photometry? What is the relationship between return stroke temperature, electrical current, and luminosity? 3) How do optical spectra and plasma properties vary among distinct lightning processes, such as return strokes, M components, and stepped and dart leaders? 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.