Occurrences of Auroral Kilometric Radiations in Van Allen Radiation Belts
Abstract:
Fuliang Xiao1, Qinghua Zhou1, Zhenpeng Su2
1 School of Physics and Electronic Sciences, Changsha University of Science and Technology, Changsha 410004, China,
2 Chinese Academy of Sciences Key Laboratory for Basic Plasma Physics, University of Science and Technology of China, Hefei 230026, China,
Superluminous auroral kilometric radiation (AKR) is a strong terrestrial radio emission and dominates at higher latitudes because of reflection in vicinities of the source cavity and plasmapause. Recently, Van Allen Probes have observed occurrences of AKR emission in the equatorial region of Earth’s radiation belts but its origin still remains an open question. Equatorial AKR can produce efficient acceleration of radiation belt electrons and is a risk to space weather. Here we report high-resolution observations during two small storm periods 4–6 April and 18–20 May 2013 and show, using a 3-D ray tracing simulation, that AKR can propagate downward all the way into the equatorial plane in the radiation belts under appropriate conditions. The simulated results can successfully explain the observed AKR’s spatial distribution and frequency range, and the current results have a wide application to all other magnetized astrophysical objects in the universe.