Scientists discover new electromagnetic wave impacting Earth's radiation belts
A groundbreaking discovery has been made by two scientists from the University of Alaska Fairbanks, Professor Emeritus Vikas Sonwalkar and Assistant Professor Amani Reddy. They have identified a new type of "whistler," an electromagnetic wave that transports significant amounts of lightning energy into Earth's magnetosphere. This research was recently published in the journal Science Advances.
New wave challenges previous beliefs of lightning energy
The newly discovered wave, named "specularly reflected whistler," carries lightning energy into the ionosphere at low latitudes and then to the magnetosphere. This energy is reflected upward by the lower boundary of the ionosphere, approximately 88.5km above sea level, in the opposite hemisphere. This finding challenges previous beliefs that such energy remained confined within the ionosphere without reaching Earth's radiation belts.
Understanding radiation belts is crucial for space operations
Sonwalkar emphasized the importance of understanding radiation belts and the variety of electromagnetic waves that affect them, including those originating from terrestrial lightning. He stated, "We as a society are dependent on space technology." He further explained that modern communication and navigation systems, satellites, and spacecraft with astronauts aboard encounter harmful energetic particles from the radiation belts. These particles can damage electronics and cause cancer.
Coexistence of two types of whistler waves
The research also revealed that lightning energy entering the ionosphere at higher latitudes reaches the magnetosphere as a different type of whistler, named "magnetospherically reflected whistler." This wave undergoes one or more reflections within the magnetosphere. Both types of whistlers—specularly reflected and magnetospherically reflected—coexist in Earth's magnetosphere, according to Sonwalkar and Reddy's research.
New model shows doubling of lightning energy
The scientists used plasma wave data from NASA's Van Allen Probes and lightning details from the World Wide Lightning Detection Network for their research. They created a wave propagation model that showed a doubling of lightning energy reaching the magnetosphere when considering specularly reflected whistlers. This suggests that specularly reflected whistlers likely carry more lightning energy to the magnetosphere than their magnetospherically reflected counterparts.
