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

Breneman, A. W.; Wygant, J. R.; Tian, S.; Cattell, C. A.; Thaller, S. A.; Goetz, K.; Tyler, E.; Colpitts, C. A.; Dai, Lei; Kersten, K.; Bonnell, J. W.; Bale, S. D.; Mozer, F. S.; Dalton, G.; Ergun, R. E.; Malaspina, D.; Kletzing, C. A.; Kŭrth, W. S.; Hospodarsky, G. B.; Smith, C. W.; Holzworth, R. H.; Lejosne, S.; Agapitov, O. V.; Artemyev, А. V.; Hudson, M. K.; Strangeway, R. J.; Baker, D. N.; Li, X.; Albert, J. M.; Foster, J. C.; Erickson, P. J.; Chaston, C. C.; Mann, I. R.; Donovan, E.; Cully, C. M.; Krasnoselskikh, V.; Blake, J. B.; Millan, R. M.; Halford, A. J.

doi:10.1007/s11214-022-00934-y

Cited by 17 publications

(14 citation statements)

References 180 publications

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“…The electric fields are obtained in modified Geocentric Solar Ecliptic (mGSE) coordinate system. Spin‐fit electric field y‐component is the spin plane electric field, oriented nearly duskward at spin period cadence (∼11 s) in the mGSE coordinate system (Breneman et al., 2022). The spin fitting procedure involves a least‐square fitting for each spin period of the Ey component of the onboard determined spin plane electric field.…”

Section: Methodsmentioning

confidence: 99%

Formation of Electron Zebra Stripes Observed on 8 September 2017

et al. 2023

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Zebra stripes are the characteristic structures having repeated hills and valleys in the electron flux intensities observed below L = 3. We delineate the fundamental properties and evolution of electron zebra stripes by modeling advection using time‐dependent electric fields provided by a global magnetohydrodynamics simulation. At the beginning of the simulation, the electrons were uniformly distributed in longitude. Some electrons moved inward due to enhanced westward electric field transients in the premidnight‐postdawn region. The inwardly displaced electrons were confined in a narrow longitudinal range and underwent grad‐B and curvature drifts. For any specific fixed position, the electrons periodically passed through the point with an energy dependent period, giving rise to the hills and valleys in the electron differential flux also known as zebra stripes. The valleys of the zebra stripes are composed of the electrons that underwent outward displacement, or no significant radial displacement. On the nightside, the duskside convection cell is skewed toward dawn in the equatorward of the auroral oval, and the westward electric field becomes dominant in the postdawn region, which results in the inward motion of the electrons. The spatial distribution of the westward electric field is consistent with observation. Zebra stripes are a mixture of the electrons that have and have not experienced inward transport due to solar wind‐inner magnetosphere coupling by way of the ionosphere.

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Section: Methodsmentioning

confidence: 99%

Formation of Electron Zebra Stripes Observed on 8 September 2017

et al. 2023

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“…Specifically, we utilize the data from the fluxgate magnetometer which records the magnetic field at a maximum sampling rate of 64 Hz, and the waveform frequency receiver (WFR) that provides wave magnetic power spectra from 10 Hz to 12 kHz. The electric field data are provided by the electric fields and waves (EFW) instruments at a maximum sampling rate of 32 Hz (Breneman et al., 2022; Wygant et al., 2013) and used to identify low‐harmonic MS waves. For low‐energy protons, we utilize the data from the Helium Oxygen Proton Electron (HOPE) instrument of the Energetic Particle Composition and Thermal Plasma Suite which provides measurements of electrons and ions over the 1 eV to 50 keV energy range with full pitch angle coverage (Funsten et al., 2013; Spence et al., 2013).…”

Section: Data and Event Selectionmentioning

confidence: 99%

On the Energy Coupling From Magnetosonic Waves to High‐Frequency Electromagnetic Ion Cyclotron Waves: Statistical Analysis

Min,

2023

JGR Space Physics

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In the inner magnetosphere, fast magnetosonic waves (MS waves) are known to resonantly interact with ring current protons, causing these protons to gain energy preferentially in the direction perpendicular to the background magnetic field. An anisotropic distribution of enhanced ring current protons is a necessary condition to excite electromagnetic ion cyclotron (EMIC) waves which are known to facilitate a rapid depletion of ultra‐relativistic electrons in the outer radiation belt. So, when a simultaneous observation of high‐frequency EMIC (HFEMIC) waves, anisotropic low‐energy protons, and MS waves was first reported, a chain of energy flow from MS waves to HFEMIC waves through proton heating was naturally proposed. In this study, we carry out a statistical analysis using Van Allen Probes data to provide deeper insights into this energy pathway. Our results show that the occurrence of HFEMIC waves exhibits good correlation with the enhanced flux and anisotropy of low‐energy protons, but the correlation between the low‐energy protons and the concurrent MS waves is rather poor. The latter result is given support by quasilinear diffusion analysis, indicating negligible momentum diffusion rates at sub‐keV energies, unless MS wave frequency gets very close to the proton cyclotron frequency (which constitutes only a small number of the cases). The fact that the first chain of the coupling is statistically inconclusive calls for an alternative explanation for the major source of the low‐energy anisotropic proton population in the inner magnetosphere.

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“…Third, both THEMIS and the Van Allen Probes measure with high‐fidelity long‐wire antennas a two‐component electric field in the spin plane; in this study we utilize the Level‐2 THEMIS EFI data and Level‐3 Van Allen Probes EFW data, both which use the

\boldsymbol{E}\cdot \boldsymbol{B}=0

approximation to estimate the third component of the electric field. THEMIS data is further calibrated using SPEDAS (Angelopoulos et al., 2019) while Van Allen Probes Level‐3 data has undergone extensive processing by the EFW team (Breneman et al., 2022). Finally, regardless of calibration and data processing it is still possible for poor quality electric and magnetic field data to exist leading to anomalous PSDs.…”

Section: Methodsmentioning

confidence: 99%

A New Four‐Component L*‐Dependent Model for Radial Diffusion Based on Solar Wind and Magnetospheric Drivers of ULF Waves

et al. 2023

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Waves which couple to energetic electrons are particularly important in space weather, as they drive rapid changes in the topology and intensity of Earth's outer radiation belt during geomagnetic storms. This includes Ultra Low Frequency (ULF) waves that interact with electrons via radial diffusion which can lead to electron dropouts via outward transport and rapid electron acceleration via inward transport. In radiation belt simulations, the strength of this interaction is specified by ULF wave radial diffusion coefficients. In this paper we detail the development of new models of electric and magnetic radial diffusion coefficients derived from in‐situ observations of the azimuthal electric field and compressional magnetic field. The new models use L∗ ${L}^{\ast }$ as it accounts for adiabatic changes due to the dynamic magnetic field coupled with an optimized set of four components of solar wind and geomagnetic activity, Bz ${B}_{z}$, V $V$, Pnormaldnormalynormaln ${P}_{\mathrm{d}\mathrm{y}\mathrm{n}}$, and normalSnormalynormalm−H $\mathrm{S}\mathrm{y}\mathrm{m}-H$, as independent variables (inputs). These independent variables are known drivers of ULF waves and offer the ability to calculate diffusion coefficients at a higher cadence then existing models based on Kp. We investigate the performance of the new models by characterizing the model residuals as a function of each independent variable and by comparing to existing radial diffusion models during a quiet geomagnetic period and through a geomagnetic storm. We find that the models developed here perform well under varying levels of activity and have a larger slope or steeper gradient as a function of L∗ ${L}^{\ast }$ as compared to existing models (higher diffusion at higher L∗ ${L}^{\ast }$ values).

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

Cited by 17 publications

References 180 publications

Formation of Electron Zebra Stripes Observed on 8 September 2017

Formation of Electron Zebra Stripes Observed on 8 September 2017

On the Energy Coupling From Magnetosonic Waves to High‐Frequency Electromagnetic Ion Cyclotron Waves: Statistical Analysis

A New Four‐Component L*‐Dependent Model for Radial Diffusion Based on Solar Wind and Magnetospheric Drivers of ULF Waves

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