Identifying the Driver of Pulsating Aurora

Nishimura, Y.; Bortnik, J.; Li, W.; Thorne, R. M.; Lyons, L. R.; Angelopoulos, V.; Mende, S. B.; Bonnell, J. W.; Contel, O. Le; Cully, C. M.; Ergun, R. E.; Auster, U.

doi:10.1126/science.1193186

Cited by 275 publications

(350 citation statements)

References 28 publications

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“…Thus, some correlation is expected between the electron precipitation features and chorus emissions, as shown by Tsuruda et al [1981], Nishimura et al [2010], and Ozaki et al [2012] using pulsating aurora images. In this paper we conducted a correlation analysis of the ELF/VLF emissions with cosmic noise absorption (CNA) measured by a 30 MHz riometer with a time resolution of 1 s at Meanook,Canada (54.61 • N, 246.65…”

Section: Correlation Analysis With Respect To Cosmic Noise Absorptionmentioning

confidence: 91%

“…These waves interact with high-energy (10-100 keV) electrons and cause modulation of spectacular pulsating auroras [e.g., Tsuruda et al, 1981;Nishimura et al, 2010;Miyoshi et al, 2010;Lessard, 2012;Li et al, 2012;Ozaki et al, 2012]. ELF/VLF chorus emissions can also interact with relativistic electrons in the radiation belts, contributing to their acceleration and dissipation in the inner magnetosphere [e.g., Miyoshi et al, 2003Miyoshi et al, , 2007Katoh and Omura, 2007;Kasahara et al, 2009].…”

Section: Introductionmentioning

confidence: 99%

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Ground‐based ELF/VLF chorus observations at subauroral latitudes—VLF‐CHAIN Campaign

et al. 2014

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We report observations of very low frequency (VLF) and extremely low frequency (ELF) chorus waves taken during the ELF/VLF Campaign observation with High-resolution Aurora Imaging Network (VLF-CHAIN) of 17-25 February 2012 at subauroral latitudes at Athabasca (L = 4.3), Canada. ELF/VLF waves were measured continuously with a sampling rate of 100 kHz to monitor daily variations in ELF/VLF emissions and derive their detailed structures. We found quasiperiodic (QP) emissions whose repetition period changes rapidly within a period of 1 h without corresponding magnetic pulsations. QP emissions showed positive correlation between amplitude and frequency sweep rate, similarly to rising-tone elements. We found an event of nearly simultaneous enhancements of QP emissions and Pc1/electromagnetic ion cyclotron wave intensities, suggesting that the temperature anisotropy of electrons and ions developed simultaneously at the equatorial plane of the magnetosphere. We also found QP emissions whose intensity suddenly increased in association with storm sudden commencement without changing their frequency. Falling-tone ELF/VLF emissions were observed with their rate of frequency change varying from 0.7 to 0.05 kHz/s over 10 min. Bursty-patch emissions in the lower and upper frequency bands are often observed during magnetically disturbed periods. Clear systematic correlation between these various ELF/VLF emissions and cosmic noise absorption was not obtained throughout the campaign period. These observations indicate several previously unknown features of ELF/VLF emissions in subauroral latitudes and demonstrate the importance of continuous measurements for monitoring temporal variations in these emissions.

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Section: Correlation Analysis With Respect To Cosmic Noise Absorptionmentioning

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Ground‐based ELF/VLF chorus observations at subauroral latitudes—VLF‐CHAIN Campaign

et al. 2014

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“…2 (Tsurutani and Smith 1974). Chorus is important because it plays a dual role in both the loss and local acceleration of radiation belt electrons and is the dominant scattering process leading to diffuse auroral precipitation Nishimura et al 2010; . Recent statistical analyses of the global distribution of chorus observed on the THEMIS spacecraft indicates that the power spectral density is highly variable and responds to geomagnetic activity .…”

Section: Fig 2 Spectrogram Of Waves Observed On Combined Release Andmentioning

confidence: 99%

The Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) on RBSP

et al. 2013

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The Electric and Magnetic Field Instrument and Integrated Science (EMFISIS) investigation on the NASA Radiation Belt Storm Probes (now named the Van Allen Probes) mission provides key wave and very low frequency magnetic field measurements to understand radiation belt acceleration, loss, and transport. The key science objectives and the contribution that EMFISIS makes to providing measurements as well as theory and modeling are described. The key components of the instruments suite, both electronics and sensors, including key functional parameters, calibration, and performance, demonstrate that EMFI-SIS provides the needed measurements for the science of the RBSP mission. The EMFISIS operational modes and data products, along with online availability and data tools provide the radiation belt science community with one the most complete sets of data ever collected.

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“…There are two main wave modes that can resonate with plasma sheet electrons in the equatorial plane in the energy ranges observed for pulsating aurora: electrostatic electron cyclotron harmonic (ECH) waves, which will interact with plasma sheet electrons of energies ranging from a few hundred electron volts to a few kilo-electronvolts, and electromagnetic whistlermode chorus waves, which can resonate with electrons of a few to several tens of kilo-electronvolts (Horne et al, 2003;Meredith et al, 2009). Direct evidence of the correlation between chorus waves measured by the THEMIS spacecraft and ground-based imaging of pulsating aurora was presented by Nishimura et al (2010) and was further supported by later observations of similar correlations for more events Jaynes et al, 2013). Anisotropic plasma sheet electrons provide a source of free energy for chorus excitation, and in the interaction process they get scattered into the loss cone.…”

Section: Introductionmentioning

confidence: 99%

Variations in energy, flux, and brightness of pulsating aurora measured at high time resolution

et al. 2017

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Abstract. High-resolution multispectral optical and incoherent scatter radar data are used to study the variability of pulsating aurora. Two events have been analysed, and the data combined with electron transport and ion chemistry modelling provide estimates of the energy and energy flux during both the ON and OFF periods of the pulsations. Both the energy and energy flux are found to be reduced during each OFF period compared with the ON period, and the estimates indicate that it is the number flux of foremost higher-energy electrons that is reduced. The energies are found never to drop below a few kilo-electronvolts during the OFF periods for these events. The high-resolution optical data show the occurrence of dips in brightness below the diffuse background level immediately after the ON period has ended. Each dip lasts for about a second, with a reduction in brightness of up to 70 % before the intensity increases to a steady background level again. A different kind of variation is also detected in the OFF period emissions during the second event, where a slower decrease in the background diffuse emission is seen with its brightness minimum just before the ON period, for a series of pulsations. Since the dips in the emission level during OFF are dependent on the switching between ON and OFF, this could indicate a common mechanism for the precipitation during the ON and OFF phases. A statistical analysis of brightness rise, fall, and ON times for the pulsations is also performed. It is found that the pulsations are often asymmetric, with either a slower increase of brightness or a slower fall.

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Identifying the Driver of Pulsating Aurora

Cited by 275 publications

References 28 publications

Ground‐based ELF/VLF chorus observations at subauroral latitudes—VLF‐CHAIN Campaign

Ground‐based ELF/VLF chorus observations at subauroral latitudes—VLF‐CHAIN Campaign

The Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) on RBSP

Variations in energy, flux, and brightness of pulsating aurora measured at high time resolution

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