Ionospheric Plasma Density Oscillation Related to EMIC Pc1 Waves

Kim, Hyangpyo; Shiokawa, K.; Park, Jaeheung; Miyoshi, Yoshizumi; Miyashita, Yukinaga; Stolle, Claudia; Kim, Khan‐Hyuk; Matzka, Jürgen; Buchert, Stephan; Fromm, Tanja; Hwang, Junga

doi:10.1029/2020gl089000

Cited by 9 publications

(21 citation statements)

References 36 publications

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“…This result is in contrast with the result of Kim et al. (2021) who reported using IPA crossing by the Swarm satellite in the ionosphere that the IPA was accompanied by weak upward/downward field‐aligned currents of 0.04–1 μA/m 2 . Nakamura et al.…”

Section: Event 1: Intermittent Weak Ipa On 22 April 2018contrasting

confidence: 99%

Multi‐Event Study of Simultaneous Observations of Isolated Proton Auroras at Subauroral Latitudes Using Ground All‐Sky Imagers and the Van Allen Probes

et al. 2022

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Isolated proton auroras (IPAs) appearing at subauroral latitudes are generated by energetic protons precipitating from the magnetosphere through interaction with electromagnetic ion cyclotron (EMIC) waves. Thus, an IPA is the ionospheric projection of the spatial and temporal variation of wave‐particle interaction regions in the magnetosphere. In this study, we conducted unique multi‐event analysis of simultaneous observations of IPAs and their source regions on 22 April, 7 September, and 22 March 2018, using all‐sky imagers at subauroral latitudes and the Van Allen Probes. When the satellite footprint passed over the IPAs associated with ground Pc1 geomagnetic pulsations, locally generated He+‐band EMIC waves with the same frequencies as the ground Pc1 pulsations were observed in all events. The IPAs and EMIC waves had comparable narrow widths in the latitudinal direction. The EMIC waves appeared during the rapid enhancement of the ring current proton flux at energy range of ∼10–50 keV, while they disappeared at the rapid decrease of the electron density. From these results, we conclude that the boundaries of the localized IPAs and EMIC waves were determined by the overlap region of energetic proton enhancement and the plasmasphere. This overlap of ring‐current protons and plasmasphere is a favorable condition for the pitch‐angle scattering of protons by the EMIC waves. Characteristic magnetic and electric field variations with the IPAs were not observed by the satellite, indicating that the IPAs were not accompanied by field‐aligned currents comparable to that of oval auroral arcs.

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Section: Event 1: Intermittent Weak Ipa On 22 April 2018contrasting

confidence: 99%

Multi‐Event Study of Simultaneous Observations of Isolated Proton Auroras at Subauroral Latitudes Using Ground All‐Sky Imagers and the Van Allen Probes

et al. 2022

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“…Kim, Shiokawa, Park, Miyoshi, Miyashita, et al. (2020) found that Ne oscillation events and compressional waves tended to be in‐phase when the spectral intensity was higher and the wave frequency was lower. However, we did not find such linear correlation between the phases, spectral intensity, and wave frequency.…”

Section: Statistical Resultsmentioning

confidence: 99%

Analysis of Ionospheric Compressional Waves and Electron Density Oscillation During Storm Periods Using Swarm Observations

Wang

Lühr

2022

JGR Space Physics

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Using Swarm satellite observations, we aimed to examine compressional electromagnetic ion cyclotron (EMIC) waves and concurrent plasma density oscillations during storm periods (2014–2018). Compressional waves were accompanied by precipitated energetic proton fluxes, which can lead to increased electron density in the F‐layer. Approximately one‐third of compressional waves were accompanied by electron density (Ne) oscillations. The Ne oscillation occurred more frequently during stronger magnetic storms and with EMIC wave events of larger power density. The morning sector and South Atlantic Anomaly region revealed high occurrence rates of Ne oscillations. Its peak occurrence region showed a local time drift during the storm evolution. These variations with magnetic local time and storm phases are consistent with those of EMIC waves. Phases of the EMIC compressional waves and Ne oscillations exhibited a strong correlation. The phases of EMIC waves and Ne oscillations were linearly related, apart from a bias of ∼17.5° or 200.5°. The relative amplitude ratio of most Ne oscillations to the compressional EMIC wave showed a strong correlation with the local Alfven velocity. When the Alfven velocity increased, the relative amplitude ratio also increased, and there appeared a saturation of the relative amplitude ratio at large Alfven velocity.

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“…Kim, Shiokawa, Park, Miyoshi, Miyashita et al. (2021) reported two cases of plasma density oscillation correlated with Pc1 wave, but a statistical study is still lacking. We have used 16 Hz Ne measurements from Swarm to perform this investigation.…”

Section: Discussionmentioning

confidence: 99%

“…Kim, Shiokawa, Park, Miyoshi, Miyashita et al. (2021) studied the relationship between ionospheric EMIC parallel waves and electron density. They pointed out that the parallel wave occurred when Ne was >10 3.5 cm −3 .…”

Section: Discussionmentioning

confidence: 99%

Magnetic Local Time and Latitude Distribution of Ionospheric Large‐Spatial‐Scale EMIC Wave Events: Swarm Observations

et al. 2022

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In the present work, the magnetic local time and latitude (MLT and MLat) distributions of ionospheric large‐spatial‐scale (>20° MLat) electromagnetic ion cyclotron waves were investigated using high‐resolution 50‐Hz geomagnetic field data from Swarm A and B satellites. Both parallel and transverse waves were studied in a comparative manner for different geomagnetic activities and seasons. Frequent occurrences of large‐spatial‐scale waves in the South Atlantic Anomaly and North America, where the parallel waves propagate over the longest distance, were observed. Waves appear mostly in the 02–10 MLT sector wherein the pre‐noon parallel waves propagate farthest in latitudinal range. With the enhancement of geomagnetic activity, both transverse and parallel waves increase in occurrence. The dayside occurrence rate is higher during weak geomagnetic activity, whereas the situation is reversed on the nightside and duskside. The dayside waves are located outside the mid‐latitude trough, and the nightside waves are located near (inside) the equatorward boundary of the mid‐latitude trough. Large‐spatial‐scale waves tend to occur at the equinoxes when the absolute value of the dipole tilt angle is less than 10°, while the long‐distance transmission in the waveguide occurs in the pre‐noon in summer. Parallel waves propagate in the region where the electron density is higher than that of the transverse waves. There is a close relationship between EMIC wave and electron density oscillation.

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Ionospheric Plasma Density Oscillation Related to EMIC Pc1 Waves

Cited by 9 publications

References 36 publications

Multi‐Event Study of Simultaneous Observations of Isolated Proton Auroras at Subauroral Latitudes Using Ground All‐Sky Imagers and the Van Allen Probes

Multi‐Event Study of Simultaneous Observations of Isolated Proton Auroras at Subauroral Latitudes Using Ground All‐Sky Imagers and the Van Allen Probes

Analysis of Ionospheric Compressional Waves and Electron Density Oscillation During Storm Periods Using Swarm Observations

Magnetic Local Time and Latitude Distribution of Ionospheric Large‐Spatial‐Scale EMIC Wave Events: Swarm Observations

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