Archaeo-Aurora and Geomagnetic Secular Variation in Historic Time

Keimatsu, Mitsuo; Fukushima, Naoshi; Nagata, T.

doi:10.5636/jgg.20.45

Cited by 30 publications

(18 citation statements)

References 3 publications

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“…First order comparisons between dipole axis longitudes and aurora sightings at different times in Greece, Rome, the Middle East [18] and China [19] between the 7 th century BC and 1000 AD indicate some agreement between favourable shielding conditions and aurora sightings and invite further studies.…”

mentioning

confidence: 87%

Reconstructing the Holocene geomagnetic field

Korte

Constable

Donadini

et al. 2011

Earth and Planetary Science Letters

283

258

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mentioning

confidence: 87%

Reconstructing the Holocene geomagnetic field

Korte

Constable

Donadini

et al. 2011

Earth and Planetary Science Letters

283

258

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“…] It is now necessary to consider the implications of recurrent auroral activity at mid-latitudes in East Asia during medieval times. Several authors have suggested that the high medieval occurrence frequency of aurorae over China, Japan and Korea, particularly during the twelfth century, resulted from the north geomagnetic pole being located in the Eastern Hemisphere (probably at East Asian longitudes) during this period (Keimatsu et al, 1968;Siscoe and Verosub, 1983;Fukushima et al, 1987;Oguti, 1993a;Fukushima, 1994;Oguti and Egeland, 1995;Silverman, 1998). It should just be mentioned that the combinatorial calculations performed by Siscoe and Verosub (1983) now need to be repeated in the light of the three simultaneous ("common" or "overlap") medieval auroral observations reported by Willis and Stephenson (2000).…”

Section: Scientific Interpretation Of the Ancient Solar And Auroral Omentioning

confidence: 99%

Solar and auroral evidence for an intense recurrent geomagnetic storm during December in AD 1128

Willis

Stephenson

2001

Ann. Geophys.

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Abstract. The earliest known drawing of sunspots appears in The Chronicle of John of Worcester, which was compiled in the first half of the twelfth century. In this medieval chronicle, the Latin text describing the sunspots is accompanied by a colourful drawing, albeit idealised, which shows the apparent positions and sizes of two sunspots on the solar disk. The date of this observation of sunspots from Worcester, England is firmly established as AD 1128 December 8. Assuming that the drawing was prepared fairly carefully, the angular diameters of the two sunspots are at least about 3 arcmin and 2 arcmin in the northern and southern hemispheres, respectively. Similarly, the heliographic latitudes of both sunspots are within the approximate range of 25 • -35 • . About five days after this observation of sunspots on the solar disk, on the night of AD 1128 December 13, a red auroral display was observed from Songdo, Korea (the modern city of Kaesong). This auroral observation was recorded in the Koryo-sa, the official Korean chronicle of the period. In addition, five Chinese and five Korean descriptions of auroral displays were recorded in various East-Asian histories between the middle of AD 1127 and the middle of AD 1129. The ten oriental auroral records in this particular interval correspond to six distinct auroral events, which provide evidence for recurrent, though possibly intermittent, auroral activity on a timescale almost exactly equal to the synodic-solar-rotation period (approximately 27 days). The six distinct auroral events were apparently associated with two series of recurrent geomagnetic storms, both of which were sufficiently intense to produce mid-latitude auroral displays in East Asia. These ancient solar and auroral observations are interpreted in terms of present-day understanding of solar-terrestrial physics. Contemporary ground-based and satellite measurements during the last few decades have indicated that recurrent geomagnetic storms are usually a feature of the declining phase of the solar cycle. In addition, the strength of such recurrent geomagnetic storms has been classified as moderate rather than intense. The recurrent geomagnetic storms occurring dur-ing the interval AD 1127-1129 must have been sufficiently intense to produce mid-latitude auroral displays over China and Korea, some of which appeared or extended south of the observing site. This last statement remains true even after proper allowance is made for the fact that during the twelfth century, the north geomagnetic pole was probably situated at the usual high geographic latitude, but in the same geographic longitude range as East Asia. Therefore, it may be inferred that the two series of intense recurrent geomagnetic storms occurred near a medieval maximum in the "elevenyear" solar cycle. Moreover, the overall level of solar activity appears to have been especially high at the end of the second decade of the twelfth century.

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“…The auroral zones are observed to be centered on the dipole axis rather than the rotational axis (VESTINE, 1944). Changes in auroral zone positions associated with longitudinal drift of the dipole axis have been inferred from historical auroral records (KEIMATSU et al, 1968). But the polar latitude of the magnetic poles has confined the auroral zones to high latitudes throughout historic times, as indicated by the historical compilation of FRITZ (1881) (reproduced for example in CHAPMAN and BARTELS (1940)) and by the more recent studies of SCHOVE (1955).…”

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Effects of Geomagnetic Dipole Variations on the Auroral Zone Locations

Siscoe¹,

Christopher²

1975

J. geomagn. geoelec

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The purpose of this note is to point out: 1) that during geomagnetic reversals and excursion, the zones of frequent auroral occurrence will be located at very different geographical positions than at present; and 2) that two of the most recent excursions that have been suggested, the Laschamp-Gothenburg and the Lake Mungo events, are dated in upper paleolithic period (ca. 12,000 yr BP and 30,000yr BP respectively (NOEL and TARLING, 1975;MoRNER and LANSER, 1975;BARBETTI and MCELHINNY, 1972;FREED and HEALY, 1974)), and could have produced frequent auroral displays to major populations of stone age people. The second point might be important because it opens the possibility that some of the previously uninterpreted artifacts and drawings from this period could be representations of auroral forms.At present the aurora are seen most frequently in fairly narrow, approximately latitudinal bands around 70 north and south. In these so-called auroral zones, the aurora is a nightly occurrence.The location of the auroral zones is determined by the present values of the strength and orientation of the magnetic dipole of the earth and by average solar wind parameters.Statistics of auroral occurrence at low latitudes are governed by the statistics of variations of certain solar wind parameters.We assume for this discussion that solar wind averages and statistics have remained constant in time, and look at the changes in the location of the auroral zones that result from changes in the geomagnetic field that occur during reversals and excursions.In particular we concentrate in this note on the effect of decreasing the strength of the dipole, and on excursions of the dipole axis.There is not complete agreement among paleomagnetists about whether the dipole axis actually moves much during one of these events or whether the ap-*On leave from the

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Archaeo-Aurora and Geomagnetic Secular Variation in Historic Time

Cited by 30 publications

References 3 publications

Reconstructing the Holocene geomagnetic field

Reconstructing the Holocene geomagnetic field

Solar and auroral evidence for an intense recurrent geomagnetic storm during December in AD 1128

Effects of Geomagnetic Dipole Variations on the Auroral Zone Locations

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