Spatial Evolution of Wave‐Particle Interaction Region Deduced From Flash‐Type Auroras and Chorus‐Ray Tracing

Ozaki, Mitsunori; Inoue, Tomohiro; Tanaka, Yoshimasa; Yagitani, Satoshi; Kasahara, Yoshiya; Shiokawa, K.; Imamura, Kousuke; Hosokawa, K.; Oyama, Shin‐ichiro; Kataoka, Ryuho; Ebihara, Yusuke; Ogawa, Y.; Kadokura, Akira

doi:10.1029/2021ja029254

Cited by 4 publications

(10 citation statements)

References 80 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Typical pulsating auroras show quasi‐periodic luminous modulations related to a bundle of chorus elements (Kasahara et al., 2018; Miyoshi et al., 2010; Nishimura et al., 2020), but flash aurora shows a transient luminous response related to an isolated chorus element. The typical duration and patchy size of flash auroras are less than 1 s and less than 4,000 km 2 , respectively (Ozaki et al., 2021). Kataoka et al.…”

Section: Methodsmentioning

confidence: 99%

“…Typical pulsating auroras show quasi-periodic luminous modulations related to a bundle of chorus elements (Kasahara et al, 2018;Miyoshi et al, 2010;Nishimura et al, 2020), but flash aurora shows a transient luminous response related to an isolated chorus element. The typical duration and patchy size of flash auroras are less than 1 s and less than 4,000 km 2 , respectively (Ozaki et al, 2021). Kataoka et al (2012) reported a rapid 54-Hz modulation in a standard periodic pulsating auroral event, but such rapid luminous modulations are different from the transient luminous emission of the isolated flash aurora.…”

Section: Methodsmentioning

confidence: 99%

“…The model calculation is the same as Ozaki et al. (2021). The electron density (see Figure S1 in Supporting Information ), geomagnetic field line, and energetic electron flux are used from the GCPM 2.2 (Gallagher et al., 2000), Tsyganenko 2002 (Tsyganenko, 2002), and AE9 (Ginet et al., 2013) models applied for the observation time, respectively.…”

Section: Numerical Analysismentioning

confidence: 99%

“…To assess whether the temporal characteristics of flash aurora reflect the chorus wave properties, we used a model calculation that included the effects of nonducted wave propagation in detail. The model calculation is the same as Ozaki et al (2021). The electron density (see Figure S1 in Supporting Information S1), geomagnetic field line, and energetic electron flux are used from the GCPM 2.2 (Gallagher et al, 2000), Tsyganenko 2002(Tsyganenko, 2002, and AE9 (Ginet et al, 2013) models applied for the observation time, respectively.…”

Section: Numerical Modelmentioning

confidence: 99%

“…The EMCCD data release is partly supported by the IUGONET (Inter-university Upper atmosphere Global Observation NETwork) project (http://www.iugonet.org/). The ray tracing model and the CER calculation are presented by Ozaki et al (2021).…”

Section: Data Availability Statementmentioning

confidence: 99%

See 4 more Smart Citations

Slow Contraction of Flash Aurora Induced by an Isolated Chorus Element Ranging From Lower‐Band to Upper‐Band Frequencies in the Source Region

Ozaki

Yagitani

Shiokawa

et al. 2022

Geophysical Research Letters

Self Cite

View full text Add to dashboard Cite

A pure single chorus element can promptly accelerate seed electrons to energies of mega-electron-volts through wave-particle interactions (Foster et al., 2017). Additionally, an isolated chorus element can rapidly scatter energetic electrons over a very wide energy range in the magnetosphere into the loss cone, and then illuminate flash auroras in the ionosphere Abstract Flash aurora driven by an isolated chorus element can be a useful ionospheric indicator for identifying the source wave properties via wave-particle interactions. Using ground observation and modeling approaches, here we report the temporal characteristics of flash aurora that depend on the chorus frequency width and the sweep rate. We found that the contraction time increases more than the expansion time in patchy auroral variations, due to the difference in the minimum electron energies resonated with the chorus wave packet away from the equatorial source to higher latitudes. Especially, the contraction time strongly depends on the higher-frequency chorus waves due to cyclotron resonance with lower-energy electrons. The model calculations support that the chorus element ranges from lower-band to upper-band frequencies with respect to half the gyrofrequency at the exact generation region. Our study provides the prompt (milliseconds) chorusdriven electron dynamics through the spatiotemporal characteristics of flash aurora in the ionosphere. Plain Language SummaryThe wave frequency of a chorus wave, which is one of the electromagnetic wave emissions in magnetized plasmas, is an important parameter for characterizing energetic particles in the Earth's magnetosphere. Even though chorus waves are classified into two bands-lower-and upper-band frequencies separated at half the electron gyrofrequency-it is not well established that both lower-and upper-band chorus are essentially the same at the generation region. In this study, we investigate temporal characteristics of specific aurora caused by discrete chorus elements to identify the whole frequency band of chorus waves at the magnetospheric generation region. The aurora reflects the physical properties of the magnetospheric processes through the geomagnetic field lines from the generation region; thus, the aurora in the ionosphere becomes an ionospheric display on which the magnetospheric chorus waves are generated. Using auroral images along with model calculations, we find that the contraction time is longer than the expansion time as auroras vary their shape, depending on the frequency width of chorus wave packets. This study provides a new insight into the role of rapid (milliseconds) resonant interaction processes between discrete chorus elements and electrons over a wider energy range.

show abstract

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Numerical Analysismentioning

confidence: 99%

Section: Numerical Modelmentioning

confidence: 99%

Section: Data Availability Statementmentioning

confidence: 99%

See 3 more Smart Citations

Slow Contraction of Flash Aurora Induced by an Isolated Chorus Element Ranging From Lower‐Band to Upper‐Band Frequencies in the Source Region

Ozaki

Yagitani

Shiokawa

et al. 2022

Geophysical Research Letters

Self Cite

View full text Add to dashboard Cite

show abstract

Quantifying the size and duration of a microburst-producing chorus region on 5 December 2017

Elliott

Breneman

Colpitts

et al. 2022

Preprint

Self Cite

View full text Add to dashboard Cite

Many competing processes contribute to the dynamic formation and depletion of the Earth's radiation belts, including radial transport, local wave acceleration, particle loss to the magnetopause, particle precipitation into the atmosphere, and others (see review by Ripoll et al., 2020;Thorne, 2010). These competing mechanisms typically occur simultaneously and are energy dependent; understanding the importance of each is fundamental to radiation belt physics.Electron microbursts are impulsive (<1 s) injections of energetic (few keV to >MeV) electrons into the atmosphere that may represent a major loss source from the radiation belt during storm main phase and recovery (Millan & Thorne, 2007). Microburst electron precipitation was first observed in the 1960s by balloon measurements of bremsstrahlung X-rays produced by precipitating electrons as they enter Earth's atmosphere (K. A.

show abstract

Quantifying the Size and Duration of a Microburst‐Producing Chorus Region on 5 December 2017

Elliott

Breneman

Colpitts

et al. 2022

Geophysical Research Letters

Self Cite

View full text Add to dashboard Cite

show abstract

Spatial Evolution of Wave‐Particle Interaction Region Deduced From Flash‐Type Auroras and Chorus‐Ray Tracing

Abstract: Cyclotron resonant wave-particle interactions are of fundamental importance as ubiquitous drivers of particle heating, acceleration, and precipitation throughout supernova remnants (

Cited by 4 publications

References 80 publications

Slow Contraction of Flash Aurora Induced by an Isolated Chorus Element Ranging From Lower‐Band to Upper‐Band Frequencies in the Source Region

Slow Contraction of Flash Aurora Induced by an Isolated Chorus Element Ranging From Lower‐Band to Upper‐Band Frequencies in the Source Region

Quantifying the size and duration of a microburst-producing chorus region on 5 December 2017

Quantifying the Size and Duration of a Microburst‐Producing Chorus Region on 5 December 2017

Contact Info

Product

Resources

About