ULF Wave Driven Radial Diffusion During Geomagnetic Storms: A Statistical Analysis of Van Allen Probes Observations

Sandhu, Jasmine; Rae, I. J.; Wygant, J. R.; Breneman, A. W.; Tian, S.; Watt, Clare E. J.; Horne, Richard B.; Ozeke, L. G.; Γεωργίου, Μαρίνα; Walach, Maria-Theresia

doi:10.1029/2020ja029024

Cited by 36 publications

(69 citation statements)

References 122 publications

(246 reference statements)

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“…The statistical and event study analysis confirms some expected and previously observed features of externally driven compressional ULF wave propagation in the inner magnetosphere during geomagnetic storms, and also demonstrates the importance of phenomena that has received comparatively less attention. In direct agreement with previous results (e.g., Sandhu, Rae, Wygant, et al, 2021;Simms et al, 2010), we report significant enhancements in ULF wave power during the main phase of geomagnetic storms, associated with elevated solar wind conditions and a high level of solar wind -magnetosphere coupling. The main phase enhancements occur across all observed L values, with larger enhancements at higher L values.…”

Section: Interpretation and Concluding Remarkssupporting

confidence: 93%

“…Overall, these results have significant implications for our understanding of storm time ULF wave dynamics, particularly efforts to model the magnitude of ULF wave driven radial diffusion during active periods (e.g., Brautigam & Albert, 2000;Ozeke et al, 2014;Sandhu, Rae, Wygant, et al, 2021). We demonstrate that parameterization by the L value alone is comparatively inadequate in describing the radial variation of wave power during active periods.…”

Section: Interpretation and Concluding Remarksmentioning

confidence: 82%

“…Solar wind structures, such as coronal mass ejections and corotating interaction regions are associated with strong enhancements in ULF wave power (Hudson et al, 2014;Simms et al, 2010;Zong et al, 2009). Externally driven ULF waves have a broadband nature and an occurrence peaking across the dayside sector (Liu et al, 2009;Nosé et al, 1995;Nykyri, 2013;Pahud et al, 2009;Takahashi et al, 2016;Sandhu, Rae, Wygant, et al, 2021). Internal sources are associated with enhanced substorm activity and coupling to injected particle distributions (Baddeley et al, 2005;Engebretson & Cahill, 1981;Hughes, 1983;James et al, 2016;Nosé et al, 1998;Woch et al, 1990).…”

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confidence: 99%

“…In contrast to externally driven ULF waves, these narrowband ULF waves are most probable in the afternoon, dusk, and nightside magnetic local time (MLT) sectors. Although these internal sources are enhanced during geomagnetically active times (e.g., Sandhu, Rae, Wygant, et al, 2021), it has been demonstrated that external drivers are the dominant source of ULF wave power variability across the dayside inner magnetosphere (Bentley et al, 2019).…”

mentioning

confidence: 99%

“…In this study we consider how the characteristics of ULF wave power respond to geomagnetic storms, where dramatic enhancements in ULF wave power are observed across a wide radial extent of the inner magnetosphere (Sandhu, Rae, Wygant, et al, 2021). Large increases in observed ULF wave power are attributed predominantly to the elevated solar wind conditions (increased solar wind pressure and prolonged periods of strong southward IMF), and hence an enhanced external ULF wave source.…”

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confidence: 99%

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The Roles of the Magnetopause and Plasmapause in Storm‐Time ULF Wave Power Enhancements

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The terrestrial magnetosphere is host to a wealth of electromagnetic fluctuations that communicate information and transfer energy across the magnetospheric system. Amongst the most interesting are those fluctuations occurring within the ultra low frequency (ULF) wave band with frequencies ranging from ∼1−10 mHz (Jacobs et al., 1964). ULF waves play a crucial role in wider magnetospheric dynamics, associated with radial transport of the hazardous radiation belt population and resonant interactions with non-equilibrium particle distributions (e.g., Elkington et al., 2003).Sources of ULF waves lie both internally and externally to the magnetosphere. External sources include Kelvin-Helmholtz instabilities at the magnetopause flanks (Chen & Hasegawa,

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Section: Interpretation and Concluding Remarkssupporting

confidence: 93%

Section: Interpretation and Concluding Remarksmentioning

confidence: 82%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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The Roles of the Magnetopause and Plasmapause in Storm‐Time ULF Wave Power Enhancements

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Drift Phase Structure Implications for Radiation Belt Transport

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et al. 2022

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We examine drift phase structure in the electron radiation belt observations to differentiate radial transport mechanisms. Impulsive electrostatic or electromagnetic fields can cause radial transport and produce drift echoes (periodic drift phase structures with energy-dependent period). Narrow-band standing electromagnetic wave fields can also cause radial transport, while producing energy-independent periodic drift phase structures. Broad-band, random-phase electromagnetic wave fields can cause radial transport, but do not necessarily produce drift phase structure. We present results of three case studies showing little association between drift phase structure and ˜MeV electron flux enhancements in the outer belt. We estimate the amplitude of drift phase structures expected for impulsive or narrow-band interactions to compete with broad-band, randomphase waves. We show that the observed drift phase structure is typically much smaller than would be present if either impulses or narrow-band waves were the dominant cause of radial transport. We conclude that radial transport is primarily consistent with the broad-band, random-phase, small perturbations assumed in quasilinear diffusion theory, although we cannot rule out the unlikely possibility that radial transport plays little role in radiation belt dynamics.

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The Van Allen Probes Electric Field and Waves Instrument: Science Results, Measurements, and Access to Data

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The Van Allen Probes Electric Fields and Waves (EFW) instrument provided measurements of electric fields and spacecraft floating potentials over a wide dynamic range from DC to 6.5 kHz near the equatorial plane of the inner magnetosphere between 600 km altitude and 5.8 Re geocentric distance from October 2012 to November 2019. The two identical instruments provided data to investigate the quasi-static and low frequency fields that drive large-scale convection, waves induced by interplanetary shock impacts that result in rapid relativistic particle energization, ultra-low frequency (ULF) MHD waves which can drive radial diffusion, and higher frequency wave fields and time domain structures that provide particle pitch angle scattering and energization. In addition, measurements of the spacecraft potential provided a density estimate in cold plasmas ($<20~\text{eV}$ < 20 eV ) from 10 to $3000~\text{cm}^{-3}$ 3000 cm − 3 . The EFW instrument provided analog electric field signals to EMFISIS for wave analysis, and it received 3d analog signals from the EMFISIS search coil sensors for inclusion in high time resolution waveform data.The electric fields and potentials were measured by current-biased spherical sensors deployed at the end of four 50 m booms in the spacecraft spin plane (spin period $\sim11~\text{sec}$ ∼ 11 sec ) and a pair of stacer booms with a total tip-tip separation of 15 m along the spin axis. Survey waveform measurements at 16 and/or 32 S/sec (with a nominal uncertainty of 0.3 mV/m over the prime mission) were available continuously while burst waveform captures at up to 16,384 S/sec provided high frequency waveforms.This post-mission paper provides the reader with information useful for accessing, understanding and using EFW data. Selected science results are discussed and used to highlight instrument capabilities. Science quantities, data quality and error sources, and analysis routines are documented.

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ULF Wave Driven Radial Diffusion During Geomagnetic Storms: A Statistical Analysis of Van Allen Probes Observations

Cited by 36 publications

References 122 publications

The Roles of the Magnetopause and Plasmapause in Storm‐Time ULF Wave Power Enhancements

The Roles of the Magnetopause and Plasmapause in Storm‐Time ULF Wave Power Enhancements

Drift Phase Structure Implications for Radiation Belt Transport

The Van Allen Probes Electric Field and Waves Instrument: Science Results, Measurements, and Access to Data

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