Scientists from the University of Alaska in Fairbanks (UAF) have discovered a new type of electromagnetic waves which they have named “Mirror reflected whistling atmospheres”.
These atmospheres, also known as Vistlers, are low-frequency electromagnetic waves that propagate in the Earth’s ionosphere and are characterized by a whistling sound. They are generated as a result of the interaction of radio waves from thunderstorm discharges with charged particles.
Previously, it was thought that the energy from lightning strikes in the ionosphere at low latitudes remained confined there and did not reach the Earth’s radiation belts. However, a new study has completely overturned this assumption. Mirror reflected Vistlers transfer energy to the magnetosphere at heights of approximately 20 thousand kilometers, a crucial area of near-Earth space.
Professor Vikas Sonvalkar highlighted the importance of this discovery: “Our society relies on space technologies. Modern communication systems, navigation systems, satellites, and spacecraft carrying astronauts are vulnerable to harmful energy within the radiation belts, which can damage electronics and pose a risk of cancer. Understanding these processes, particularly those arising from earthly lightning, is crucial for human activities in space.”
Mirror reflected whistling atmospheres differ from magnetospheric depressions as they reflect lightning energy back downwards at the lower boundary of the ionosphere in the opposite hemisphere.
Researchers utilized archival data on plasma waves gathered by NASA Van Allen missions and information from the Global Lightning Detection Network (GLD360). Through this data, they developed a wave propagation model that demonstrated a doubling of energy reaching the magnetosphere when considering mirror reflected whistling atmospheres. Given that the majority of lightning strikes occur in tropical and subtropical regions, this discovery holds significant implications for understanding the dynamics of Earth’s magnetosphere.
This study by scientists builds upon decades of research into the impact of lightning-generated Vistlers on the physics of radiation belts, with this field of science being actively developed since the 1950s.