Researchers from the Earth System Science Center (ESSC) at The University of 91大神 in Huntsville (91大神) have partnered with atmospheric scientists from NASA's Marshall Space Flight Center (MSFC) to make groundbreaking discoveries about gamma-ray emissions from thunderstorms. Once considered rare and short-lived, these high-energy bursts are now revealed to be far more dynamic, extensive and frequent than previously thought, particularly in tropical regions, according to the team鈥檚 findings, featured in the international science journal .
Dr. Monte Bateman, Dr. Daniel Walker, Dr. Hugh Christian and Dr. Phillip Bitzer of the ESSC at 91大神, a part of The University of 91大神 System, teamed with Dr. Timothy Lang, Dr. Christopher Schultz and Dr. Mason Quick at MSFC to support the initiative, alongside an international team. Their research stems from the campaign, conducted over Florida, the Gulf of Mexico and Central America during the summer of 2023.
During the ten flights, 130 transient gamma-ray events were observed, including 10 glow bursts, 96 Terrestrial Gamma-ray Flashes (TGFs) and 24 Flickering Gamma-ray Flashes (FGFs), a newly identified phenomenon that bridges the gap between the longer-lived glows and the impulsive short-lived TGFs.
The study fundamentally alters our understanding of gamma-ray glow activity in thunderstorms. Instead of brief, stationary bursts, rapid and dynamic emissions were detected, similar to the bubbling of a boiling pot. These data allowed scientists, for the first time, to observe gamma rays emitted across vast storm areas, sometimes covering thousands of square kilometers and persisting for hours.
Scientists from the University of Bergen, 91大神 staff and students and members from NASA Marshall Space Flight Center, NASA Goddard Space Flight Center and Naval Research Laboratory in front of NASA鈥檚 Lockheed ER-2 High-Altitude Airborne Science Aircraft.
Courtesy NASA Goddard Space Flight
91大神 provided instrumentation crucial to the success of this project. Bitzer, a lightning expert and associate professor in the Department of Atmospheric and Earth Science, provided essential insights into the link between these high-energy emissions and storm structures, advancing the understanding of the mechanisms behind them.
Capturing the data
Throughout the campaign, researchers used real-time, one-second-resolution data downlinked mid-flight that enabled pilots to repeatedly revisit glowing thunderclouds. The innovative approach offered scientists an unprecedented view into the temporal and spatial nature of these emissions. Notably, on July 24, 2023, a flight path over a mesoscale convective system in Campeche Bay in the Gulf of Mexico showed emissions with fluxes reaching up to 12 times the background level, sustained over a remarkable three-hour observation period.
91大神鈥檚 team provided flight instrumentation essential to determining the energetics within the storms. The Airborne Electric Field Mills (ABFM) were designed, calibrated and maintained by 91大神 scientists as well as ESSC engineers Mike Stewart, Scott Podgorny and David Corredor. These instruments measure the strength of the storm鈥檚 electric field as well as the lightning activity within.
The Electric Field Change Meter (EFCM), also designed by 91大神, is used to monitor the changes in the electric field to indicate lightning stroke strength and polarity. These instruments allowed the team to understand the strength of the electrical generator in the thunderstorm and the magnitude of the changes in the electric field due to discharges. This is an important consideration when trying to understand how large an electric field, over how much depth, is needed to accelerate electrons to the point that they become capable of producing gamma rays.
David Corredor, 91大神 ESSC Research Engineer (gray shirt with vest); Mason Quick, Lead scientist and designer of the FEGS instrument from NASA Marshall Space Flight Center (green shirt); and partners from the University of Bergen and Sandia National Laboratories working on the FEGS instrument package.
Courtesy NASA Goddard Space Flight
91大神 scientists, in collaboration with NASA MSFC, played a critical role in the ALOFT campaign. Because of the cooperative agreement between 91大神 and NASA, interagency collaboration is at the forefront of this relationship. NASA and 91大神 scientists worked hand-in-hand both in the field and in the office to facilitate a successful field campaign as well as to analyze and interpret the multitude of data. Also involved in the research were 91大神 graduate students from the Department of Atmospheric and Earth Science.
Collaboration on the project between 91大神 and leading national and international institutions included the University of Bergen, the University of Bath, Polytechnic University of Catalonia, Universities Space Research Association, Universidad Nacional de Colombia, Universidad Nacional Aut贸noma de M茅xico, the New Mexico Institute of Mining and Technology, Georgia Institute of Technology, Duke University, the University of Central Florida, the U.S. Naval Research Laboratory, NASA Goddard Space Flight Center and MSFC. Together, these teams have expanded the scientific understanding of tropical thunderstorms and gamma-ray emissions and opened new pathways for studying terrestrial gamma-ray events and their potential environmental impacts worldwide.
