Morphology of the pulsating aurora

Kvifte, G.; Pettersen, Helge Egil Seime

doi:10.1016/0032-0633(69)90148-2

Cited by 29 publications

(28 citation statements)

References 9 publications

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“…[30] Pulsating aurora is typically observed after auroral breakup in the postmidnight local time sector, and morningside pulsating aurora can occur even during times of low magnetic activity. Observations by Kvifte and Pettersen [1969] and Oguti et al [1981] show maximum occurrence rates of up to 75% and 100% (after 0400 MLT), respectively, for post-midnight pulsating aurora during solar maximum. Jones et al [2011] report occurrence rates increasing to nearly 60% by around 0300 MLT and remaining high into morning hours, during solar minimum, with single event durations of 9 h and longer.…”

Section: Discussion and Summary Of Observationsmentioning

confidence: 95%

“…Pulsating aurora is typically observed after auroral breakup in the postmidnight local time sector, and morningside pulsating aurora can occur even during times of low magnetic activity. Observations by Kvifte and Pettersen [] and Oguti et al . [] show maximum occurrence rates of up to 75% and 100% (after 0400 MLT), respectively, for post‐midnight pulsating aurora during solar maximum.…”

Section: Discussion and Summary Of Observationsmentioning

confidence: 99%

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Persistent, widespread pulsating aurora: A case study

et al. 2013

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Observations of a pulsating aurora event occurring on 11 February 2008, using the Time History of Events and Macroscale Interactions during Substorms (THEMIS) All‐Sky Imager (ASI) array, indicate a spatially and temporally continuous event with a duration of greater than 15 h and covering a region with a maximum size of greater than 10 h magnetic local time. The optical pulsations are at times locally interrupted or drowned out by auroral substorm activity but are observed in the same location once the discrete aurora recedes. The pulsations following the auroral breakup appear to be brighter and have a larger patch size than before breakup. This suggests that, while the onset of pulsating aurora is not necessarily dependent upon a substorm precursor, the pulsations are affected and possibly enhanced by the substorm process. The long duration of this pulsating aurora event, lasting approximately 8 h without interruption as imaged from Gillam station, is significantly longer than the typical 2–3 h substorm recovery phase, suggesting that pulsating aurora is not strictly a recovery phase phenomenon. This paper is accompanied by a movie of the THEMIS ASI array data, from 0000 to 1715 UT, plotted in mosaic and superimposed onto a map of North America.

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Section: Discussion and Summary Of Observationsmentioning

confidence: 95%

Section: Discussion and Summary Of Observationsmentioning

confidence: 99%

Persistent, widespread pulsating aurora: A case study

et al. 2013

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“…Both the occurrence in the morning sector and the patchy appearance of pulsating aurorae can perhaps be explained by the presence of wave propagation ducts or regions of enhanced plasma density at high altitudes. This is a natural assumption, and there is strong evidence that the mechanism that controls the pulsations is located at high altitudes [Kvifte and Pettersen, 1969]. The evidence is mainly in the relative delay times of electrons precipitating with various energies [Smith et al, 1980;Yau et al, 1981; An alternate explanation for the patchy structure of pulsating aurorae and other morningside aurorae has been offered by Chiu et al [1983].…”

Section: The Determinationmentioning

confidence: 99%

Pitch angle diffusion in morningside aurorae: 2. The formation of repetitive auroral pulsations

Davidson¹

1986

J. Geophys. Res.

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Filling of the loss cone by pitch angle diffusion will quench the growth of VLF waves that interact with substorm‐injected electrons in the morningside auroral region. This occurs for any wave mode whose growth rate is sensitive to the anisotropy of the electron distribution near the loss cone. A pair of coupled nonlinear differential equations is developed to describe the coupling between the growth of waves and the pitch angle diffusion of electrons. The equations differ from those previously used to model repetitive precipitation pulsations (Davidson, 1979) in that the wave growth in the earlier model was assumed to be sensitive mainly to the total electron flux. The earlier model therefore was limited by the strong diffusion lifetime. The pulsation periods in the earlier model were too long and strongly damped. The new model predicts cyclic or repetitive precipitation pulsations for a wide range of conditions, with periods of 3–30 s, and negligible damping. The model agrees well with an extensive body of observational data.

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“…Kvifte and Pettersen (1969) report that pulsating aurora start in the auroral oval at approximately magnetic midnight, corresponding to the time of typical substorm onset (Tanskanen, 2009). Pulsations are mentioned to occur in diffuse aurorae by Swift (1979), but it is not made clear whether these are in the growth phase or during the postonset recovery.…”

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confidence: 99%

Pulsating aurora and cosmic noise absorption associated with growth-phase arcs

McKay¹,

Partamies²,

Vierinen³

2018

Ann. Geophys.

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Abstract. The initial stage of a magnetospheric substorm is the growth phase, which typically lasts 1-2 h. During the growth phase, an equatorward moving, east-west extended, optical auroral arc is observed. This is called a growth-phase arc. This work aims to characterize the optical emission and riometer absorption signatures associated with growth-phase arcs of isolated substorms. This is done using simultaneous all-sky camera and imaging riometer observations. The optical and riometric observations allow determination of the location of the precipitation within growth-phase arcs of low-( < 10 keV) and high-(> 10 keV) energy electrons, respectively. The observations indicate that growth-phase arcs have the following characteristics:1. The peak of the cosmic noise absorption (CNA) arc is equatorward of the optical emission arc. This CNA is contained within the region of diffuse aurora on the equatorward side.2. Optical pulsating aurora are seen in the border region between the diffuse emission region on the equatorward side and the bright growth-phase arc on the poleward side. CNA is detected in the same region.3. There is no evidence of pulsations in the CNA.4. Once the equatorward drift starts, it proceeds at constant speed, with uniform separation between the growthphase arc and CNA of 40 ± 10 km.Optical pulsating aurora are known to be prominent in the post-onset phase of a substorm. The fact that pulsations are also seen in a fairly localized region during the growth phase shows that the substorm expansion-phase dynamics are not required to closely precede the pulsating aurora.

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Morphology of the pulsating aurora

Cited by 29 publications

References 9 publications

Persistent, widespread pulsating aurora: A case study

Persistent, widespread pulsating aurora: A case study

Pitch angle diffusion in morningside aurorae: 2. The formation of repetitive auroral pulsations

Pulsating aurora and cosmic noise absorption associated with growth-phase arcs

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