Modeling the dawn/dusk asymmetry of field line resonances

Andrew N. Wright, Tom Elsden, Kazue Takahashi

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)


Field line resonances (FLRs) are observed to occur preferentially, and have larger amplitudes, at dawn compared to dusk. We present simulations of FLR excitation in a magnetospheric waveguide that can reproduce this behavior. Crucially, our equilibrium is asymmetric about noon. Even when this system is driven in a symmetric fashion about noon, the fast waves that are established in the magnetosphere develop asymmetries – as do the FLRs they excite. Fast mode ray trajectories are employed to show that the asymmetry evolves due to refraction. Preferential FLR excitation at dawn is further reinforced by calculating the Resonance Map. This shows that the Resonant Zone at dawn coincides with a large-amplitude coherent fast mode driver, which is not the case at dusk. These factors result in FLRs having a larger amplitude at dawn compared to dusk.
Original languageEnglish
Pages (from-to)6443-6456
Number of pages14
JournalJournal of Geophysical Research: Space Physics
Issue number8
Early online date17 Aug 2018
Publication statusPublished - Aug 2018


  • Field line resonances
  • Pc5 ULF waves
  • 3-D Alfvén resonances
  • Magnetospheric waveguide


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