Origin of Electron Boomerang Stripes: Statistical Study
Abstract In the outer radiation belt, localized ULF waves can interact with energetic electrons by drift resonance, leading to quasiperiodic oscillations. The oscillations in the pitch angle spectrum can be characterized by either boomerang-shaped or straight stripes. Previous studies have shown that boomerang-shaped stripes evolve from straight ones when electrons drift away from the localized wave interaction region. Based on the time-of-flight technique on the pitch angle-dependent drift velocity, the origin can be remotely identified from the pitch angle dispersion. We report 27 straight stripe events and 86 boomerang-shaped events observed by Van Allen Probes from 2013/01/01 to 2017/12/31. Statistical study shows a good coincidence between the locations of straight ones and traceback regions from boomerang-shaped ones. These locations, mainly located in noon-to-dusk region, coincide well with the plasmaspheric plumes. Thus localized ULF waves trapped in the plume may result in the preference of localized ULF waves-electron interactions at noon-to-dusk region.
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Geophysical Research Letters
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