Chorus Wave Vector Orientations in the Context of the Chorus-to-Hiss Mechanism: EMFISIS Burst Mode Observations

0518078 - ÚFA 2020 US eng A - Abstrakt
Hartley, D. - Chen, L. - Kletzing, C. - Horne, R. - Santolík, Ondřej
Chorus Wave Vector Orientations in the Context of the Chorus-to-Hiss Mechanism: EMFISIS Burst Mode Observations.
AGU Fall Meeting. Washington: American Geophysical Union, 2019. SM43A-04.
[AGU Fall Meeting 2019. 09.12.2019-13.12.2019, San Francisco]
Institucionální podpora: RVO:68378289
Klíčová slova: plasmasphere * chorus waves * plasmaspheric hiss * plasmaspheric plume * Van Allen Probes
Obor OECD: Fluids and plasma physics (including surface physics)
https://agu.confex.com/agu/fm19/meetingapp.cgi/Paper/554276

In a recent study we evaluated the angular distribution of chorus waves and determined the fraction of power observed with the wave vector direction required to propagate into the plasmasphere and potentially evolve into plasmaspheric hiss. It was found that a significant fraction of chorus wave power could access the plasmasphere only when the chorus source was located in close proximity to a plasmaspheric plume. For other source locations, only a very small fraction of chorus wave power could access the plasmasphere. This analysis was performed using Van Allen Probes EMFISIS survey data, which is based on a 0.5s waveform capture every 6s. However, it has been reported that the wave vector angle can vary substantially within a single chorus subpacket. These small-timescale variations cannot be resolved when analyzing data captured in survey mode. Here, high-resolution burst mode observations of chorus waves from the Van Allen Probes EMFISIS Waves instrument are used to evaluate the angular distribution of occurrence and wave power, considering both polar and azimuthal wave vector angles. Analysis of high-resolution burst mode data allows us to take strides towards accounting for short-timescale variations in the wave vector angle. The angular distributions obtained from burst mode observations are then compared to those obtained using data captured in survey mode. This allows us to identify any features that may be overlooked when considering solely survey mode data. In addressing these differences, we consider the impact of these short-timescale variations and revisit the angular distribution of chorus waves in the context of the chorus-to-hiss mechanism, paying particular attention to waves occurring close to plasmaspheric plumes.
Trvalý link: http://hdl.handle.net/11104/0303269