Sporadic auroras near the geomagnetic equator: in the Philippines, on 27 October 1856

Hayakawa, Hisashi; Vaquero, J. M.; Ebihara, Yusuke

doi:10.5194/angeo-36-1153-2018

Cited by 6 publications

(12 citation statements)

References 69 publications

(100 reference statements)

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“…The aurora description presented by Liais is consistent with sporadic aurorae (Abbe, 1895;Botley, 1963;Silverman, 2003). In addition, the very low magnetic latitude of Rio de Janeiro and the weak/mild magnetic activity during the observations are consistent with a previous sporadic aurora observation near the magnetic equator (Hayakawa, Vaquero, & Ebihara, 2018).…”

Section: Conclusion and A Final Remarksupporting

confidence: 87%

“…Silverman (2003) provided a survey of considerable sporadic aurora observations in low-latitude regions of the United States during a time span of over half a century, and highlighted the occurrence of sporadic aurorae in the context of mid-to low-latitude aurorae during moderate to low magnetic activity. That paper was later followed by other papers with reports on sporadic aurora sightings from Iberia and the Canary Islands (Vaquero, Trigo, & Gallego, 2007;Vázquez & Vaquero, 2010), East Asia (Willis, Stephenson, & Fang, 2007), Mexico (Vaquero, Gallego, & Domínguez-Castro, 2013), and the Philippines (Hayakawa, Vaquero, & Ebihara, 2018). Interestingly, Shiokawa et al (2005) reported three cases of instrumental observations of mid-latitude aurora in Hokkaido (Japan) under fairly moderate magnetic activity as well.…”

Section: Introductionmentioning

confidence: 90%

“…However, despite being impressive, this space weather phenomenon is not very well known by the community. In addition, this phenomenon does not happen very often, and there are only a few publications reporting on sporadic aurora sightings (Abbe, 1895;Botley, 1963;Boyer, 1898;Hayakawa, Vaquero, & Ebihara, 2018;Silverman, 2003;Vaquero et al, 2013Vaquero et al, , 2007Vázquez & Vaquero, 2010;Willis et al, 2007).…”

Section: Conclusion and A Final Remarkmentioning

confidence: 99%

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A possible case of sporadic aurora observed at Rio de Janeiro

Oliveira

Hayakawa

Bhaskar

et al. 2020

Earth Planets Space

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Being footprints of major magnetic storms and hence major solar eruptions, midto low-latitude aurorae have been one of the pathways to understand solar-terrestrial environments. However, it has been reported that aurorae are also occasionally observed at low latitudes under low or even quiet magnetic conditions. Such phenomena are known as "sporadic aurorae". We report on a historical event observed by a scientist of the Brazilian Empire in Rio de Janeiro on 15 February 1875. We analyze this event on the basis of its spectroscopic observations, along with its visual structure and coloration, to suggest this event was a possible case of sporadic aurorae. Given the absence of worldwide aurora observations on that day as a consequence of low magnetic activity recorded on the days preceding the observation, in addition to a detailed description, the event observed can most likely be classified as a sporadic aurora. We discuss the geographic and magnetic conditions of that event. Thus, we add a possible case of sporadic aurora in the South American sector.

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Section: Conclusion and A Final Remarksupporting

confidence: 87%

Section: Introductionmentioning

confidence: 90%

Section: Conclusion and A Final Remarkmentioning

confidence: 99%

See 1 more Smart Citation

A possible case of sporadic aurora observed at Rio de Janeiro

Oliveira

Hayakawa

Bhaskar

et al. 2020

Earth Planets Space

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“…During this stormy interval, 9 records are found to contain information about the elevation angle of the aurora as listed in Table 1. Assuming the height of the upper border of the aurora, we estimate the equatorward boundary of the auroral emission region on the basis of the geometry of the dipole magnetic field line as shown in Figure 2 (See also Hayakawa et al (2018c)). We also assume that (1) the aurora is very thin in the latitudinal direction and is extended along a dipole magnetic field line, and that (2) atmospheric refraction is negligible.…”

Section: Estimation Of Equatorward Boundary Of Auroral Emission Regionmentioning

confidence: 99%

Low-latitude Aurorae during the Extreme Space Weather Events in 1859

Hayakawa

Ebihara

Hand³

et al. 2018

ApJ

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The Carrington storm (September 1/2, 1859) is one of the largest magnetic storms ever observed and it has caused global auroral displays in low-latitude areas, together with a series of multiple magnetic storms during August 28 and September 4, 1859. In this study, we revisit contemporary auroral observation records to extract information on their elevation angle, color, and direction to investigate this stormy interval in detail.We first examine their equatorward boundary of "auroral emission with multiple colors" based on descriptions of elevation angle and color. We find that their locations were 36.5° ILAT on August 28/29 and 32.7° ILAT on September 1/2, suggesting that trapped electrons moved to, at least, L~1.55 and L~1.41, respectively. The equatorward boundary of "purely red emission" was likely located at 30.8° ILAT on September 1/2.If "purely red emission" was a stable auroral red arc, it would suggest that trapped protons moved to, at least, L ~ 1.36. This reconstruction with observed auroral emission regions provides conservative estimations of magnetic storm intensities. We compare the auroral records with magnetic observations. We confirm that multiple magnetic storms occurred during this stormy interval, and that the equatorward expansion of the auroral oval is consistent with the timing of magnetic disturbances. It is possible that the August 28/29 interplanetary coronal mass ejections (ICMEs) cleared out the interplanetary medium, making the ICMEs for the Carrington storm on September 1/2 more geoeffective.

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“…Silverman (2003) reviewed these aurorae and named them "sporadic aurorae" (Silverman, 2003), setting its threshold in daily aa index as ≤55 (Silverman, 2003; see also Willis et al, 2007). They are generally faint aurorae, while their physical properties such as duration and relationship with substorms are currently under further investigations (Silverman, 2003;cf., e.g., Akasofu, 1964;Hayakawa, Vaquero, & Ebihara, 2018;Oliveira et al, 2020). Although their physical mechanism has not been fully understood, follow-up works have recovered such sporadic aurorae in other middle-to low-latitude regions (Hayakawa, Vaquero, & Ebihara, 2018;Oliveira et al, 2020;Vaquero et al, 2007;Vauqero et al, 2013;Willis et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

An Analysis of Trouvelot's Auroral Drawing on 1/2 March 1872: Plausible Evidence for Recurrent Geomagnetic Storms

et al. 2020

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This work examines Trouvelot's observations and drawing of an auroral display during the night of 1 March 1872. It is known that the auroral oval moves equatorward to midlatitude and even low latitude during large geomagnetic storms. Trouvelot's graphical record of the great aurora on 1 March 1872 has been often cited as a remarkable example of a midlatitude aurora, although it is puzzling that this apparently occurred on a geomagnetically quiet day. Kataoka et al. (2019, JSWSC, 9, A16) even criticised this as a dating error. Here, we investigate Trouvelot's descriptions and available geomagnetic measurements in detail. Our analysis shows that the original date of Trouvelot's auroral drawing is most probably accurate in local time. Moreover, Trouvelot's descriptions and the observational site show that the auroral visibility fell at the beginning of 2 March 1872 in Greenwich Mean Time (GMT). Consulting simultaneous variations of magnetograms at Helsinki and Greenwich, we found that the nightside aurora specifically coincides with the initial phase of the storm (substorm) and suggests a close association with a substorm triggered by sudden magnetospheric compression. This case study shows that short geomagnetic storms can be overlooked in a daily aa index and they can also cause midlatitude aurorae. Moreover, we found ≈27-day intervals between this storm, the extreme storms on 4-6 February 1872, and another "bright aurora" that was reported on 6 January 1872. Based on their intervals, these midlatitude aurorae have probably resulted from recurrent solar activity.

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Sporadic auroras near the geomagnetic equator: in the Philippines, on 27 October 1856

Cited by 6 publications

References 69 publications

A possible case of sporadic aurora observed at Rio de Janeiro

A possible case of sporadic aurora observed at Rio de Janeiro

Low-latitude Aurorae during the Extreme Space Weather Events in 1859

An Analysis of Trouvelot's Auroral Drawing on 1/2 March 1872: Plausible Evidence for Recurrent Geomagnetic Storms

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