Global observations of magnetospheric high‐<i>m</i> poloidal waves during the 22 June 2015 magnetic storm

Le, G.; J., P.; Strangeway, R. J.; Russell, C. T.; Slavin, J. A.; Takahashi, Kazue; Singer, H. J.; Anderson, B. J.; Bromund, K. R.; Fischer, D.; Kepko, E. L.; Magnes, W.; Nakamura, R.; Plaschke, Ferdinand; Torbert, R. B.

doi:10.1002/2017gl073048

Cited by 46 publications

(68 citation statements)

References 41 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In radiation belt models, when assessing the relative contribution of ULF waves to electron dynamics, ULF wave power is typically assumed to be broadband (e.g., Ali et al, ; Brautigam & Albert, ; Brautigam et al, ; Ozeke et al, ) and the value of m is assumed to be both positive and low for all frequencies. This is in despite of evidence for discrete wave power (e.g., Claudepierre et al, ; Mann et al, ; Rae et al, ), and both high (e.g., Le et al, ) and low (e.g., Sarris et al, ), and positive (Sarris et al, ) and negative (Le et al, ) azimuthal wave numbers within the outer radiation belt. In general, these assumptions are made for three fundamental reasons.…”

Section: Introductionmentioning

confidence: 83%

Determining the Mode, Frequency, and Azimuthal Wave Number of ULF Waves During a HSS and Moderate Geomagnetic Storm

et al. 2018

Self Cite

View full text Add to dashboard Cite

Ultralow frequency (ULF) waves play a fundamental role in the dynamics of the inner magnetosphere and outer radiation belt during geomagnetic storms. Broadband ULF wave power can transport energetic electrons via radial diffusion, and discrete ULF wave power can energize electrons through a resonant interaction. Using observations from the Magnetospheric Multiscale mission, we characterize the evolution of ULF waves during a high-speed solar wind stream (HSS) and moderate geomagnetic storm while there is an enhancement of the outer radiation belt. The Automated Flare Inference of Oscillations code is used to distinguish discrete ULF wave power from broadband wave power during the HSS. During periods of discrete wave power and utilizing the close separation of the Magnetospheric Multiscale spacecraft, we estimate the toroidal mode ULF azimuthal wave number throughout the geomagnetic storm. We concentrate on the toroidal mode as the HSS compresses the dayside magnetosphere resulting in an asymmetric magnetic field topology where toroidal mode waves can interact with energetic electrons. Analysis of the mode structure and wave numbers demonstrates that the generation of the observed ULF waves is a combination of externally driven waves, via the Kelvin-Helmholtz instability, and internally driven waves, via unstable ion distributions. Further analysis of the periods and toroidal azimuthal wave numbers suggests that these waves can couple with the core electron radiation belt population via the drift resonance during the storm. The azimuthal wave number and structure of ULF wave power (broadband or discrete) have important implications for the inner magnetospheric and radiation belt dynamics.

show abstract

Section: Introductionmentioning

confidence: 83%

Determining the Mode, Frequency, and Azimuthal Wave Number of ULF Waves During a HSS and Moderate Geomagnetic Storm

et al. 2018

Self Cite

View full text Add to dashboard Cite

show abstract

“…While standing waves observed by spacecraft usually have a second harmonic poloidal standing wave structure (Le et al, 2017;Min et al, 2017;Takahashi et al, 1985Takahashi et al, , 2018, in situ particle observation data from Van Allen Probes have confirmed the drift resonance excitation of the fundamental poloidal mode, since dE ϕ led the phase of dB r by 90°in southern hemisphere (Dai et al, 2013). While standing waves observed by spacecraft usually have a second harmonic poloidal standing wave structure (Le et al, 2017;Min et al, 2017;Takahashi et al, 1985Takahashi et al, , 2018, in situ particle observation data from Van Allen Probes have confirmed the drift resonance excitation of the fundamental poloidal mode, since dE ϕ led the phase of dB r by 90°in southern hemisphere (Dai et al, 2013).…”

Section: 1029/2018gl081573mentioning

confidence: 99%

Excitation of Storm Time Pc5 ULF Waves by Ring Current Ions Based on the Drift‐Kinetic Simulation

Yamakawa

Seki

Amano

et al. 2019

Geophysical Research Letters

View full text Add to dashboard Cite

Storm time Pc5 waves are considered to be excited through the drift‐bounce resonance by ring current ions associated with the injection from the magnetotail. Using the Geospace Environment Modeling System for Integrated Studies–Ring Current simulation, a drift‐kinetic and self‐consistent model for ring current particles, we investigate the excitation mechanism of these waves in the inner magnetosphere. The power spectra of electromagnetic field fluctuations show the excitation of both poloidal and toroidal mode waves in Pc5 frequency range. It is found that these waves are fundamental mode waves with the azimuthal wave number m~ − 20 and excited through the drift resonance with the drifting ions with energies of 80–120 keV. The simulation indicates that global distribution of wave power coincides with the positive local growth rate mainly contributed by the positive phase space density gradient in energy.

show abstract

“…ULF waves excited by internal instabilities tend to have a dominant magnetic oscillation in the radial direction and large m-number (|m| >~50), while ULF waves excited by external sources tend to have a dominant magnetic oscillation in the azimuthal direction and small m-number (|m| <~20). To estimate the m-number, several methods have been proposed: phase delay method using multiple satellites (e.g., Le et al, 2017;Takahashi et al, 1985Takahashi et al, , 2018 or ground stations (e.g., Baker et al, 2003) and the finite Larmor radius effect method (e.g., Min et al, 2017;Takahashi et al, 2018).…”

Section: Citationmentioning

confidence: 99%

Drift‐Bounce Resonance Between Pc5 Pulsations and Ions at Multiple Energies in the Nightside Magnetosphere: Arase and MMS Observations

Oimatsu

Nosé

Teramoto

et al. 2018

Geophysical Research Letters

Self Cite

View full text Add to dashboard Cite

A Pc5 wave is observed by the Exploration of energization and Radiation in Geospace Arase satellite in the inner magnetosphere (L ~5.4–6.1) near postmidnight (L‐magnetic local time ~1.8–2.5 hr) during the storm recovery phase on 27 March 2017. Its azimuthal wave number (m‐number) is estimated using two independent methods with satellites and ground observations to be −8 to −15. The direct measurement of the m‐number enables us to calculate the resonance energy. The flux oscillations of H+ and O+ ions at ≥ 56.3 keV are caused by drift resonance and those of O+ ions at ≤ 18.6 keV by bounce resonance. Resonances of O+ ions at multiple energies are simultaneously observed for the first time. The enhancement of the O+/H+ flux ratio at ≤ 18.6 keV indicates selective acceleration of O+ ions through bounce resonance.

show abstract

Global observations of magnetospheric high‐m poloidal waves during the 22 June 2015 magnetic storm

Cited by 46 publications

References 41 publications

Determining the Mode, Frequency, and Azimuthal Wave Number of ULF Waves During a HSS and Moderate Geomagnetic Storm

Determining the Mode, Frequency, and Azimuthal Wave Number of ULF Waves During a HSS and Moderate Geomagnetic Storm

Excitation of Storm Time Pc5 ULF Waves by Ring Current Ions Based on the Drift‐Kinetic Simulation

Drift‐Bounce Resonance Between Pc5 Pulsations and Ions at Multiple Energies in the Nightside Magnetosphere: Arase and MMS Observations

Contact Info

Product

Resources

About