Ionospheric Modulation by EMIC Wave‐Driven Proton Precipitation: Observations and Simulations

Tian, Xingbin; Yu, Yiqun; Gong, Fan; Ma, Longxing; Cao, Jinbin; Solomon, Stanley C.; Shreedevi, P. R.; Shiokawa, Kazuo; Otsuka, Yuichi; Oyama, Shin‐ichiro

doi:10.1029/2022ja030983

Cited by 6 publications

(4 citation statements)

References 63 publications

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“…Thus, they cannot directly affect the F/E‐regions where SAPS are formed (e.g., Mishin & Streltsov, 2021; Yu et al., 2022, and references therein). On the other hand, energetic ions, with energy fluxes higher than electron fluxes during this event, will deposit their energy above 100 km, well within the E‐region (Fang et al., 2013; Tian et al., 2023). Therefore, observations of such relativistic electron precipitation imply that SAPS may lead to dynamics in the lower altitude ionosphere, whereas the much more spread energetic ion precipitation which affects conductivity may expand the latitudinal range of SAPS effects.…”

Section: Spacecraft Observationsmentioning

confidence: 99%

Energetic Particle Precipitation in Sub‐Auroral Polarization Streams

Artemyev,

Zou,

Zhang

et al. 2024

Geophysical Research Letters

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Sub‐auroral polarization streams (SAPS) are one of the most intense manifestations of magnetosphere‐ionosphere coupling. Magnetospheric energy transport to the ionosphere within SAPS is associated with Poynting flux and the precipitation of thermal energy (0.03–30 keV) plasma sheet particles. However, much less is known about the precipitation of high‐energy (≥50 keV) ions and electrons and their contribution to the low‐altitude SAPS physics. This study examines precipitation within one SAPS event using a combination of equatorial THEMIS and low‐altitude DMSP and ELFIN observations, which, jointly, cover from a few eV up to a few MeV energy range. Observed SAPS are embedding the ion isotropy boundary, which includes strong 300–1,000 keV ion precipitation. SAPS are associated with intense precipitation of relativistic electrons (≤3 MeV), well equatorward of the electron isotropy boundary. Such relativistic electron precipitation is likely due to electron scattering by electromagnetic ion cyclotron waves at the equator.

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Section: Spacecraft Observationsmentioning

confidence: 99%

Energetic Particle Precipitation in Sub‐Auroral Polarization Streams

Artemyev,

Zou,

Zhang

et al. 2024

Geophysical Research Letters

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“…Statistical/case studies using particle flux measurements show that the localized precipitation of ions in the subauroral region has a good correlation to the occurrence of EMIC waves in the inner magnetosphere (Morley et al, 2009;Ni et al, 2016;Popova & Chernyaeva, 2018;Soraas et al, 1980Soraas et al, , 1999Tian et al, 2023). EMIC Journal of Geophysical Research: Space Physics 10.1029/2023JA032337 waves, usually classified as H-, He-and O-band waves, originate near the earth's magnetic equator and propagate along magnetic field lines in the frequency range of 0.1-5 Hz.…”

Section: Introductionmentioning

confidence: 99%

Global Distribution of EMIC Waves and Its Association to Subauroral Proton Precipitation During the 27 May 2017 Storm: Modeling and Multipoint Observations

Shreedevi,

Yu,

Miyoshi

et al. 2024

JGR Space Physics

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Recent simulation studies using the RAM‐SCB model showed that proton precipitation contributes significantly to the total energy flux deposited into the subauroral ionosphere thereby affecting the magnetosphere‐ionosphere coupling. In this study, we use the BATS‐R‐US + RAM‐SCB model to understand the evolution of ElectroMagnetic Ion Cyclotron (EMIC) waves in the inner magnetosphere, their correspondence to the proton precipitation into the subauroral ionosphere, and to assess the performance of the model in reproducing the EMIC wave‐particle interactions. During the 27 May 2017 storm, Arase and RBSP‐A satellites observed typical signatures of EMIC waves in the inner magnetosphere. Within this interval, Defense Meteorological Satellite Program (DMSP) and National Oceanic and Atmospheric Administration (NOAA)/MetOp satellites observed significant proton precipitation in the dusk‐midnight sector. Simulation results show that H‐ and He‐band EMIC waves are excited within regions of strong temperature anisotropy near the plasmapause. The simulated growth rates of EMIC waves show a similar trend to that of the EMIC wave power observed by the Arase and RBSP‐A satellites, suggesting that the model can reproduce the EMIC wave activity qualitatively. The simulated H‐band waves in the dusk sector are stronger than He‐band waves possibly due to the presence of excess protons in the boundary conditions obtained from the BATS‐R‐US code. The precipitating proton fluxes reproduced by the simulation with EMIC waves are found to agree reasonably well with the DMSP and NOAA/MetOp satellite observations. It is suggested that EMIC wave scattering of ring current ions can account for proton precipitation observed by the DMSP and MetOp satellites during the 27 May 2017 storm.

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“…EMIC waves are known to play an important role in the dynamics of the inner magnetosphere through resonance with charged particles during their gyromotion (a process called cyclotron resonance, see Kitamura et al., 2018; Omura et al., 2010), which causes the pitch‐angle scattering and precipitation of energetic protons and relativistic electrons (e.g., Chen et al., 2011; Jordanova et al., 2001; Jordanova et al., 2008; Miyoshi et al., 2008; Shprits et al., 2016; Summers & Thorne, 2003; Usanova et al., 2014). The proton precipitation into the atmosphere can in turn lead to the detached proton aurora in the subauroral region (e.g., Immel et al., 2002; Nomura et al., 2012; Sakaguchi et al., 2008; Tian et al., 2023; Yahnin et al., 2007).…”

Section: Introductionmentioning

confidence: 99%

Westward Excursion of Pc1/EMIC Waves and Their Source Protons: Paradoxical Observations From Ground and Space

Yin,

Zhou,

et al. 2024

JGR Space Physics

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Pc1 geomagnetic pulsations within the frequency range of 0.2–5 Hz, the ground signatures of electromagnetic ion cyclotron (EMIC) waves, are usually observed to progress westward. A plausible explanation is that their westward‐excursion speed is defined by the drift velocity of the source particles in the geomagnetic dipole field. In this study, this relationship is examined through conjugate observations from ground‐based and spaceborne instruments. The ground‐based observations, including Pc1 pulsations and auroral emissions, consistently demonstrate a westward‐excursion speed of ∼4–5 MLT per hour, which agrees with the time delay between EMIC wave observations at two equatorial spacecraft. Observations of the wave source particles, however, indicate an inconsistency between the slow westward excursion speed and the high energy of the wave source protons. This apparent inconsistency is reconciled by the trapping motion of energetic particles within magnetic dips, which is supported by the simultaneous flux enhancements of protons across a broad energy range between ∼50 and ∼100 keV. These results improve our understanding of the westward excursion of Pc1 pulsations, and also underscore the need for caution when directly linking their westward‐excursion speed to the energies of the source particles.

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Ionospheric Modulation by EMIC Wave‐Driven Proton Precipitation: Observations and Simulations

Abstract: Electromagnetic ion cyclotron (EMIC) waves are transverse plasma waves generated in the equatorial magnetosphere by the anisotropic energetic proton instability (

Cited by 6 publications

References 63 publications

Energetic Particle Precipitation in Sub‐Auroral Polarization Streams

Energetic Particle Precipitation in Sub‐Auroral Polarization Streams

Global Distribution of EMIC Waves and Its Association to Subauroral Proton Precipitation During the 27 May 2017 Storm: Modeling and Multipoint Observations

Westward Excursion of Pc1/EMIC Waves and Their Source Protons: Paradoxical Observations From Ground and Space

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