Isolated Proton Aurora Driven by EMIC Pc1 Wave: PWING, Swarm, and NOAA POES Multi‐Instrument Observations

Kim, Hyangpyo; Shiokawa, Kazuo; Park, Jaeheung; Miyoshi, Yoshizumi; Miyashita, Yukinaga; Stolle, Claudia; Connor, H. K.; Hwang, Junga; Buchert, Stephan; Kwon, Hyuck Jin; Nakamura, Satoko; Nakamura, K.; Oyama, Shin‐ichiro; Otsuka, Yuichi; Nagatsuma, Tsutomu; Sakaguchi, Kaori

doi:10.1029/2021gl095090

Cited by 9 publications

(26 citation statements)

References 50 publications

(71 reference statements)

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“…Ozaki et al (2018) reported 1 Hz range modulation of IPAs and concluded that the modulation was due to intermittent proton precipitation or sub/ relativistic electrons scattered by repetitive bursts of fine-structured EMIC waves. EMIC waves that cause IPA work for MeV electron scattering (e.g., Miyoshi et al, 2008) and the density irregularity of the topside ionosphere (Kim et al, 2021).…”

mentioning

confidence: 99%

Multipoint Measurement of Fine‐Structured EMIC Waves by Arase, Van Allen Probe A, and Ground Stations

Matsuda

Miyoshi

Kasahara

et al. 2021

Geophysical Research Letters

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Fine-structured electromagnetic ion cyclotron (EMIC) waves are one type of EMIC mode waves, and ground-based Pc1 studies have reported that they are composed of clear repetitive bursts of characteristic rising tones in a typical frequency range of 0.2-5 Hz (Fukunishi et al., 1981;Troitskaya & Gul'elmi, 1967). Multipoint measurement of fine-structured EMIC waves reveals their propagation mechanism, formation mechanism, and wave-particle interaction along their propagation path. For example, Usanova et al. ( 2008) presented simultaneous ground-satellite observations of fine-structured EMIC waves and reported that the repetition periods of fine-structured EMIC waves observed on the ground and on the Time History of Events and Macroscale Interactions During Substorms (THEMIS) spacecraft were almost identical. They concluded that these observation results cannot be explained by the bouncing wave packet (BWP) model

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confidence: 99%

Multipoint Measurement of Fine‐Structured EMIC Waves by Arase, Van Allen Probe A, and Ground Stations

Matsuda

Miyoshi

Kasahara

et al. 2021

Geophysical Research Letters

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“…IPAs have been observed in connection with EMIC wave activities (e.g., Sakaguchi et al, 2007Sakaguchi et al, , 2008Sakaguchi et al, , 2015Zhang et al, 2008;Yuan et al, 2010;Kim et al, 2021). In this subsection, we shall examine the potential EMIC wave activities from both ground-based and in-situ magnetometer data.…”

Section: Ground and In-situ Magnetometer Data: Evidence Of Electromag...mentioning

confidence: 98%

“…Using data from the multi-wavelength all-sky-imagers (ASI) and induction magnetometers, Sakaguchi et al (2007; investigated the "isolated proton auroras" in the evening sector and found them coincident with Pc1 geomagnetic pulsations. Those detached/isolated proton arcs/blob/spots, despite their differences in shapes and fine structures, are now often deemed to owe their source mechanisms to the electromagnetic ion cyclotron (EMIC) wave and its resulting pitch-angle scattering of ring-current ions in the inner magnetosphere (e.g., Immel et al, 2005;Sakaguchi et al, 2007Sakaguchi et al, , 2008Sakaguchi et al, , 2015Yahnin et al, 2007;Yuan et al, 2010;Liang et al, 2014;Kim et al, 2021;Shumko et al, 2022). EMIC waves are generated in the equatorial region of the plasmaspheremagnetosphere by internal wave-particle interaction with ringcurrent ions (Fraser et al, 2005;Jordanova et al, 2007;Usanova et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

On the green isolated proton auroras during Canada thanksgiving geomagnetic storm

Liang

Gillies²,

Donovan³

et al. 2022

Front. Astron. Space Sci.

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The existence of detached/isolated auroral structures in the subauroral ionosphere has been recognized and studied for decades. One major subset of such detached auroras is the so-called “isolated proton aurora” (IPA). IPA is characterized by substantial hydrogen emissions and thus inferred to be proton aurora, but is also accompanied by other emission lines. In particular, IPA is usually dominated by 557.7 nm green-line emissions in optical luminosity. To date, there is still a lack of dedicated spectrographic study and detailed comparison among structures in different emission lines of IPA. The intensity ratios between the 557.7 nm and hydrogen emissions in IPA have not been well established from concurrent observations or theoretical models. In this study, we report an IPA event during ∼0245–0345 UT on 12 October 2021, the Canada Thanksgiving storm night. Using multi-station, multi-wavelength optical instruments, including the Transition Region Explorer (TREx) spectrograph, we investigate the evolution and spectrographic properties of the IPA. In-situ and ground magnetometer data show evidence of electromagnetic ion cyclotron (EMIC) waves associated with the passage of IPA, supporting a causal link between the EMIC wave and the proton precipitation. The precipitating proton energies are estimated to range between a few keV and a few tens of keV according to the IPA emission heights inferred from triangulation analyses. Via careful examination of the spectral intensities and the elevation-angle profiles of the 557.7, 427.8, and 486.1 nm emissions based on the spectrograph data, we conclude that the 557.7 nm emissions contained in the IPA were unlikely to owe their source to energetic electron precipitation from the magnetosphere, but were the byproduct of the proton precipitation. The intensity ratio between the 557.7 nm (427.8 nm) and the 486.1 nm emissions of the IPA are confined within a relatively narrow range around ∼26 (∼4), which may serve as validation tests for existing and developing proton transport models.

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“…Kim et al. (2020, 2021) reported that IPAs with EMIC waves were accompanied by weak field‐aligned currents using ground‐based all‐sky imager and the Swarm and POES satellites, and Pc1 geomagnetic pulsations were accompanied by ionospheric density variations of the same period.…”

Section: Introductionmentioning

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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Isolated Proton Aurora Driven by EMIC Pc1 Wave: PWING, Swarm, and NOAA POES Multi‐Instrument Observations

Cited by 9 publications

References 50 publications

Multipoint Measurement of Fine‐Structured EMIC Waves by Arase, Van Allen Probe A, and Ground Stations

Multipoint Measurement of Fine‐Structured EMIC Waves by Arase, Van Allen Probe A, and Ground Stations

On the green isolated proton auroras during Canada thanksgiving geomagnetic storm

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

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