Relation between optical emissions, particles, electric fields, and Alfvén waves in a multiple rayed arc

Hallinan, T. J.; Kimball, J.; Stenbaek‐Nielsen, H. C.; Lynch, K. A.; Arnoldy, R. L.; Bonnell, J. W.; Kintner, P. M.

doi:10.1029/2000ja000321

Cited by 25 publications

(21 citation statements)

References 10 publications

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“…This interpretation is supported by a study by Hallinan et al (2001), which combined optical and in situ rocket measurements to show that Alfvén waves appeared to be accelerated electrons dispersively in the region above tall auroral rays. The waves were also present above a curled arc, but here they appeared more of a passive indicator of a KelvinHelmholtz instability in the large-scale acceleration region and were not directly affecting the incoming particles.…”

Section: Introductionsupporting

confidence: 52%

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Morphology and dynamics of aurora at fine scale: first results from the ASK instrument

Dahlgren¹,

Ivchenko²,

Sullivan

et al. 2008

Ann. Geophys.

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Abstract. The ASK instrument (Auroral Structure and Kinetics) is a narrow field auroral imager, providing simultaneous images of aurora in three different spectral bands at multiple frames per second resolution. The three emission species studied are O + 2 (5620Å), O + (7319Å) and O (7774Å). ASK was installed and operated for the first time in an observational campaign on Svalbard, from December 2005 to March 2006. The measurements were supported by data from the Spectrographic Imaging Facility (SIF). The relation between the morphology and dynamics of the visible aurora and its spectral characteristics is studied for selected events from this period. In these events it is found that dynamic aurora is coupled to high energy electron precipitation. By studying the O + 2 /O intensity ratio we find that some auroral filaments are caused by higher energy precipitation within regions of lower energy precipitation, whereas other filaments are the result of a higher particle flux compared to the surroundings.

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Section: Introductionsupporting

confidence: 52%

“…Ivchenko et al (2004) used imaging, spectral and incoherent scatter data to show that the presence of low energy electron precipitation results in an enhancement in the O + ( 4 P− 4 D 0 ) multiplet compared to the N + 2 1N(0, 2) bands. This O + enhancement was also shown to be linked with the presence of rayed arcs.…”

Section: Introductionmentioning

confidence: 99%

Morphology and dynamics of aurora at fine scale: first results from the ASK instrument

Dahlgren¹,

Ivchenko²,

Sullivan

et al. 2008

Ann. Geophys.

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“…Using these data, they were able to conclude that very dynamic rayed aurora were present for all the observations of NEIALs. This type of aurora can be associated with Alfvénic acceleration of electrons, which produces large numbers of low energy (sub-keV) precipitating electrons (Hallinan et al, 2001;Ivchenko et al, 2005). This is also indicated in the camera data by the large altitude extent of the auroral rays .…”

Section: Ground Based Observationsmentioning

confidence: 77%

PFISR nightside observations of naturally enhanced ion acoustic lines, and their relation to boundary auroral features

et al. 2008

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Abstract. We present results from a coordinated camera and radar study of the auroral ionosphere conducted during March of 2006 from Poker Flat, Alaska. The campaign was conducted to coincide with engineering tests of the first quarter installation of the Poker Flat Incoherent Scatter Radar (PFISR). On 31 March 2006, a moderately intense auroral arc, (∼10 kR at 557.7 nm), was located in the local magnetic zenith at Poker Flat. During this event the radar observed 7 distinct periods of abnormally large backscattered power from the F-region. These were only observed in the field-aligned radar beam, and radar spectra from these seven times show naturally enhanced ion-acoustic lines (NEIALs), the first observed with PFISR. These times corresponded to (a) when the polar cap boundary of the auroral oval passed through the magnetic zenith, and (b) when small-scale filamentary dark structures were visible in the magnetic zenith. The presence of both (a) and (b) was necessary for their occurrence. Soft electron precipitation occurs near the magnetic zenith during these same times. The electron density in the vicinity where NEIALs have been observed by previous studies is roughly between 5 and 30×10 10 m −3 . Broadband extremely low frequency (BBELF) wave activity is observed in situ by satellites and sounding rockets to occur with similar morphology, during active auroral conditions, associated with the poleward edge of the aurora and soft electron precipitation. The observations presented here suggest further investigation of the idea that NEIALs and BBELF wave activity are differently-observed aspects of the same wave phenomenon. If a connection between NEIALs and BBELF can be established with more data, this could provide a link between in situ measurements of downward current regions (DCRs) and dynamic aurora, and ground-based observations of dark auroral structures and NEIALs. Identification of in situ processes, namely wave activity, in ground-based signaCorrespondence to: R. G. Michell (rmichell@swri.edu) tures could have many implications. One specific example of interest is identifying and following the temporal and spatial evolution of regions of potential ion outflow over large spatial and temporal scales using ground-based optical observations.

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“…Since then there have been numerous studies of these thinner, active, substorm auroral arcs such as Haerendel et al (1994); Stenbaek-Nielsen et al (1998); Hallinan et al (2001). However, a more recent examination of the Maggs and Davis (1968) data set by Stenbaek-Nielsen et al (1999), revealed that a significant fraction of those observations were taken inside diffuse aurora, showcasing that the context in which auroral research takes place is largely defined by it.…”

Section: Introductionmentioning

confidence: 99%

“…Previous studies have focused on active aurora (Hallinan et al, 2001;Stenbaek-Nielsen et al, 1998), but less on diffuse structures, such as Peticolas et al (2002). More recently, Sergienko et al (2008) investigated the fine structure of diffuse aurora.…”

Section: Samara Et Al: Diffuse Auroramentioning

confidence: 99%

Ground-based observations of diffuse auroral structures in conjunction with Reimei measurements

et al. 2010

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Abstract. We present results from ground-based auroral observations coordinated with the Japanese satellite, Reimei, that took place during the winters of 2006, 2007 and 2008 at Poker Flat, Alaska. Comparable temporal and spatial resolution for the optical and in situ particle data, allowed for investigation of small scale and/or rapidly time-varying auroral structures. Four satellite passes through diffuse auroral structures were identified. The structures within the aurora, whether stationary or time-varying (pulsating aurora), were most closely correlated with the highest energy precipitating electrons measured by these detectors (8 to 12 keV). This relation is found to be consistent across all four examples, revealing that the electron precipitation responsible for these diffuse auroral structures is primarily that of the ≥8 keV electrons.

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Relation between optical emissions, particles, electric fields, and Alfvén waves in a multiple rayed arc

Cited by 25 publications

References 10 publications

Morphology and dynamics of aurora at fine scale: first results from the ASK instrument

Morphology and dynamics of aurora at fine scale: first results from the ASK instrument

PFISR nightside observations of naturally enhanced ion acoustic lines, and their relation to boundary auroral features

Ground-based observations of diffuse auroral structures in conjunction with Reimei measurements

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