Energetic Electron Precipitation Associated With Pulsating Aurora Observed by VLF Radio Propagation During the Recovery Phase of a Substorm on 27 March 2017

Tsuchiya, F.; Hirai, A.; Obara, Takao; Misawa, Hiroaki; Kurita, Satoshi; Miyoshi, Yoshizumi; Shiokawa, K.; Connors, Martin; Ozaki, Mitsunori; Kasahara, Yoshiya; Kumamoto, A.; Kasaba, Yasumasa; Matsuoka, A.; Motomizu, Shoji; Shinohara, I.

doi:10.1029/2018gl080222

Cited by 8 publications

(7 citation statements)

References 56 publications

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“…Earlier rocket measurements of PsA showed that precipitating electrons have energies between 2 and 140 keV (McEwen et al, 1981; Sandahl, 1984; Whalen et al, 1971). A more recent study by Tsuchiya et al (2018) found that PsA is associated with relativistic electron precipitation with energy range >100 keV using very low frequency (VLF) subionospheric radio wave propagation.…”

Section: Introductionmentioning

confidence: 99%

Observations of Electron Precipitation During Pulsating Aurora and Its Chemical Impact

et al. 2020

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Pulsating auroras (PsAs) are low-intensity diffuse aurora, which switch on and off with a quasiperiodic oscillation period from a few seconds to ∼10 s. They are predominantly observed after magnetic midnight, during the recovery phase of substorms and at the equatorward boundary of the auroral oval. PsAs are caused by precipitating energetic electrons, which span a wide range of energies between tens and hundreds of keV. Such energetic PsA electrons will deposit their energy at mesospheric altitudes and induce atmospheric chemical changes. To examine the effects of energetic PsA electrons on the atmosphere, we first collect electron flux and energy measurements from low-latitude spacecraft to construct a typical energy spectrum of precipitating electrons during PsA. Among the 840 PsA events identified using ground-based auroral all-sky camera (ASC) network over the Fennoscandian region, 253 events were observed by DMSP, POES, and FAST spacecraft over the common field of view of five ASCs. The combined measurements from these spacecraft enable us to obtain an energy spectrum consisting of nonrelativistic and relativistic (30 eV to 1,000 keV) electrons during PsA. The median spectrum was found to be in good agreement with earlier estimates of the PsA spectra. We then use the Sodankylä Ion-neutral Chemistry (SIC) model to assess the chemical effect of PsA electrons. The observed extreme and median spectra of PsA produce a significant depletion in the mesospheric odd oxygen concentration up to 78%.

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Section: Introductionmentioning

confidence: 99%

Observations of Electron Precipitation During Pulsating Aurora and Its Chemical Impact

et al. 2020

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“…Miyoshi, Oyama, et al (2015) demonstrated that a few-hundred-keV electrons precipitate into the mesosphere during the pulsating aurora, and the characteristics of chorus waves simultaneously observed by Van Allen Probes well explained such wide-energy electron precipitations. Grandin et al (2017) and Tsuchiya et al (2018) showed that tens-of-keV electrons simultaneously precipitate into the upper atmosphere from ground-based observations. More recently, Miyoshi et al (2021) showed the precipitation of ∼3 MeV electron by LBC associated with pulsating aurora by coordinated observations Arase and the European Incoherent Scatter (EISCAT) radar.…”

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confidence: 99%

Simultaneous Pulsating Aurora and Microburst Observations With Ground‐Based Fast Auroral Imagers and CubeSat FIREBIRD‐II

Kawamura

Sakanoi

Fukizawa

et al. 2021

Geophysical Research Letters

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A pulsating aurora is a type of diffuse aurora usually occurring on the morning side (Akasofu, 1968) and characterized by brightness modulation in both space and time. The modulating period of the pulsating aurora has a hierarchical structure. A few to a few-tens of second modulation is called the main pulsation, and a ∼3-Hz modulation embedded within the main pulsation is called the internal modulation. The pulsating aurora is produced by the precipitation of magnetospheric electrons with energies ranging from a few to tens of keV through pitch angle scattering due to the whistler-mode chorus waves near the magnetic equator (e.g.,

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“…The other possible source was the lower-band chorus waves, which could cause pitch-angle scattering of both diff use/pulsating auroral electrons [39][40][41][42][43] and more energetic electrons [44,4]. Energetic electron precipitations due to the chorus wave have been observed by VLF/LF transmitter signals [45] and riometers [46]. Figure 8 shows a dynamic spectrum in the VLF range observed at ATHA at 05:35 UT.…”

Section: Discussionmentioning

confidence: 99%

ULF modulation of energetic electron precipitation observed by VLF/LF radio propagation

Miyashita

Ohya

Tsuchiya

et al. 2020

URSI Radio Sci. Bull.

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We investigated the modulation of D-region signatures due to ultra-low-frequency (ULF) waves using very-lowfrequency/low-frequency (VLF/LF) radio propagation. Three transmitters from the United States (NLK, NDK, and WWVB) were received at Athabasca (ATHA), Canada. We observed oscillations in intensities and phases on the NDK-ATHA and WWVB-ATHA paths with a period of 3 to 4 minutes, associated with ULF waves during a substorm at 05:25-05:45 UT on 4 June, 2017. This is the fi rst observational report showing clear VLF/LF oscillations in the ULF range. The ground-based H-component magneticfi eld variations and Doppler velocity observed by the SuperDARN HF radars showed the same periodic changes as seen in the VLF/LF oscillations, suggesting that energetic electron precipitation (EEP) over the WWVB-ATHA and NDK-ATHA paths was modulated by the ULF waves. Based on ground-based magnetic-fi eld data, we concluded that the ULF wave corresponded to the Pi2 pulsations associated with the substorm, because the propagation direction of the wave was westward (66.4 km/s) from the pre-midnight sector, the magnetic variations at low latitudes were inphase over wide longitudes, and the magnetic variations at ATHA slightly preceded those at low latitudes. A rising-tone chorus emission was observed in the frequency range of 5 kHz to 6 kHz at ATHA during the VLF/LF oscillations. Pitch-angle diff usion by the whistler-mode chorus wave is one possible mechanism accounting for the energetic electron precipitation.

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Energetic Electron Precipitation Associated With Pulsating Aurora Observed by VLF Radio Propagation During the Recovery Phase of a Substorm on 27 March 2017

Cited by 8 publications

References 56 publications

Observations of Electron Precipitation During Pulsating Aurora and Its Chemical Impact

Observations of Electron Precipitation During Pulsating Aurora and Its Chemical Impact

Simultaneous Pulsating Aurora and Microburst Observations With Ground‐Based Fast Auroral Imagers and CubeSat FIREBIRD‐II

ULF modulation of energetic electron precipitation observed by VLF/LF radio propagation

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