Abstract
AbstractWe report correlated data on nightside chorus waves and energetic electrons during two small storm periods: 1 November 2012 (Dst≈−45) and 14 January 2013 (Dst≈−18). The Van Allen Probes simultaneously observed strong chorus waves at locations L = 5.8–6.3, with a lower frequency band 0.1–0.5fce and a peak spectral density ∼10−4 nT2/Hz. In the same period, the fluxes and anisotropy of energetic (∼10–300 keV) electrons were greatly enhanced in the interval of large negative interplanetary magnetic field Bz. Using a bi‐Maxwellian distribution to model the observed electron distribution, we perform ray tracing simulations to show that nightside chorus waves are indeed produced by the observed electron distribution with a peak growth for a field‐aligned propagation approximately between 0.3fce and 0.4fce, at latitude <7°. Moreover, chorus waves launched with initial normal angles either θ<90° or >90° propagate along the field either northward or southward and then bounce back either away from Earth for a lower frequency or toward Earth for higher frequencies. The current results indicate that nightside chorus waves can be excited even during weak geomagnetic activities in cases of continuous injection associated with negative Bz. Moreover, we examine a dayside event during a small storm C on 8 May 2014 (Dst≈−45) and find that the observed anisotropic energetic electron distributions potentially contribute to the generation of dayside chorus waves, but this requires more thorough studies in the future.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.