Statistics of pulsating auroras on the basis of all-sky TV data from five stations. I. Occurrence frequency

Oguti, Takasi; Kokubun, S.; Hayashi, K.; Tsuruda, K.; Machida, S.; Kitamura, Teitaro; Saka, O.; Watanabe, T.

doi:10.1139/p81-152

Cited by 38 publications

(39 citation statements)

References 5 publications

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“…Oguti et al (1981) re-port that in their observations the occurrence probability of pulsating aurora at magnetic midnight is about 30 % and it rapidly increases to 100 % at about 4 h magnetic local time. Their conclusion is that pulsating aurora are a common occurrence along the auroral oval in the morning sector.…”

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confidence: 79%

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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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confidence: 79%

“…Oguti et al, 1981). Expansion/recovery-phase pulsations are mainly observed in magnetically moderate conditions with the tendency of fast solar wind driving .…”

Section: Discussionmentioning

confidence: 99%

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

McKay¹,

Partamies²,

Vierinen³

2018

Ann. Geophys.

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“…A similar study presented by Oguti et al . [] acquired better spatial coverage, spanning approximately 61.5° to 74.3° magnetic latitude in central Canada, with all‐sky cameras at five stations for 34 nights in 1980 during solar maximum. This data set shows that the occurrence rate increases from around 30% near midnight to 100% near 0400 MLT when the camera shut down due to daylight.…”

Section: Introductionmentioning

confidence: 99%

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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“…The pulsating aurora (PA) is a unique visible emission in the polar region characterized by blinking patches in the upper atmosphere with a scale size of ∼100 km and recurrence periods of ∼5–40 s [ Yamamoto , 1988]. It typically occurs on the postmidnight sector near the equatorward boundary of the auroral oval and covers a local time range that increases with increasing geomagnetic activity, even extending as far as to the dayside [ Royrvik and Davis , 1977; Oguti et al , 1981; Jones et al , 2011]. On the basis of rocket and low‐altitude spacecraft measurements made simultaneously with auroral imaging, such auroral pulsations are known to be caused by quasiperiodic precipitation of electrons with energies of tens of keV into the upper atmosphere [ Johnstone , 1978; Sandahl et al , 1980; Samara et al , 2010].…”

Section: Introductionmentioning

confidence: 99%

Multievent study of the correlation between pulsating aurora and whistler mode chorus emissions

et al. 2011

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[1] A multievent study was performed using conjugate measurements of the Time History of Events and Macroscale Interactions during Substorms (THEMIS) spacecraft and an all-sky imager during periods of intense lower-band chorus waves. The thirteen identified cases support our previous finding, based on two events, that the intensity modulation of lower-band chorus near the magnetic equator is highly correlated with quasiperiodic pulsating auroral emissions near the spacecraft's magnetic footprint, indicating that lower-band chorus is the driver of the pulsating aurora. Furthermore, we identified a fortuitous measurement made simultaneously by two THEMIS spacecraft with small spatial separation. The two spacecraft were found to be located in a single pulsating chorus patch and the spacecraft footprints were in the same pulsating auroral patch when intense chorus bursts were measured simultaneously, whereas only one of the spacecraft's footprints was in a patch when the other spacecraft did not detect intense chorus. On the basis of this event, we can estimate the pulsating chorus patch size by mapping the pulsating auroral patches from the ionosphere toward the magnetic equator, giving a roughly circular region of ∼5000 km diameter for corresponding azimuthally elongated patches with ∼100 km size in the ionosphere. Using a ray-tracing-based calculation of the divergence of chorus raypaths from a point source, together with the corresponding resonant energies, we found that the chorus patch size is most probably not a result of ray divergence but a property of the wave excitation region.Citation: Nishimura, Y., et al. (2011), Multievent study of the correlation between pulsating aurora and whistler mode chorus emissions,

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Statistics of pulsating auroras on the basis of all-sky TV data from five stations. I. Occurrence frequency

Cited by 38 publications

References 5 publications

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

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

Persistent, widespread pulsating aurora: A case study

Multievent study of the correlation between pulsating aurora and whistler mode chorus emissions

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