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14C increase 775 and 993 AD:
Aurora observations in ancient times.
M. A. Shea
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Jull et al., 2014
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Possible explanations:
Extreme Solar Proton EventComet Collision - January 773Gamma-ray Burst – Super Nova
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HOW CAN OUR MODERN KNOWLEDGE
HELP IN THE UNDERSTANDING OF HISTORICAL PHENOMENA?
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COMMONLY USED GEOPHYSICAL DATABASES
Satellite data – IMF, solar wind, proton events (1965-present)
Cosmic radiation data (1935 – present)Solar flare reports (1932 - present)Geomagnetic indices (1864 - present)Geomagnetic data (~1828-present)Sunspot Number (~1700 - present)Auroral lists (1000 – present)
(some earlier records from ~210 BC to 1000)
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SOLAR AND GEOMAGNETIC DATA-SELECTED EVENTS
EVENT SOLAR GLE GMS AA* RANK ACTIVITY INDEX
22 Mar 91 28 E No Yes 176 7410 Mar 89 22 E No Yes 441 125 Jul 46 15 E Yes Yes 329 1128 Feb 42 4 E Yes Yes 168 8021 May 90 37 W Yes No19 Nov 49 72 W Yes No23 Feb 56 80 W Yes Yes 131 1667 Mar 42 90 W Yes No29 Sep 89 105 W Yes No
5 Oct 60 N/A No Yes 253 28
AA* Index: 1868-2010
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THINGS WE HAVE LEARNED:
MAJOR SPEs FROM CENTRAL MERIDIAN ACTIVITYGENERALLY HAVE SOFTER SPECTRA THAN EVENTS FROM THE WEST LIMB.
MAJOR HIGH ENERGY ( 4 GeV) SPEs FROM CENTRAL MERIDIAN ACTIVITY ARE RARE.
MAJOR HIGH ENERGY SPEs ARE NOT ALWAYS ASSOCIATED WITH A SUBSEQUENT GEOMAGNETIC STORM.
MAJOR GEOMAGNETIC STORMS CAN OCCUR WITHOUT A LARGE SPE.
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CAN IDENTIFICATION OF LOW LATITUDE AURORA HELP TO RESOLVE UNUSUAL GEOPHYSICAL RECORDS SUCH AS 14C INCREASES IN TREE RINGS?
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EARTH'S GEOMAGNETIC FIELD IS RAPIDLY EVOLVING IN GEOPHYSICAL TIME
THE GEOMAGNETIC LATITUDE OF AURORAL OBSERVATIONS SHOULD BE CALCULATED FOR THE EPOCH OF THE OBSERVATION
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CHANGE IN MAGNITUDE OF THE G(1,0) TERM OF THE EARTH’S MAGNETIC FIELD, 1600-2010
(18% decrease in 400 years)
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CHANGES IN THE POSITION OF THE EARTH’S DIPOLE1000 AD – 2000 AD
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CHANGES IN THE POSITION OF THE EARTH’S DIPOLE
0 AD TO 1990 AD
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EXAMPLES OF GEOMAGNETIC LATITUDE CHANGES
LOCATION 1000 2000 CHANGE
S. SPAIN 35° N 40° N 5° NSAN DIEGO 25° N 40° N 15° NCHICAGO 36° N 51° N 15° NEGYPT 34° N 28° N 6° STASMANIA 38° S 50° S 12° S
(VALUES ARE APPROXIMATE)
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HISTORIC MID AND LOW LATITUDE AURORA
• Oct 817 Iraq• 816/817 Yemen• Oct 879 Morocco• 939-940 Syria• May 941 Spain• Aug 977 Egypt• Sept 979 Morocco• 991-992 Egypt*• Apr 1050 Egypt*• 1059-1060 Egypt
• 1176 Syria*• May 1179 Syria• Nov 1203 Yemen• 1223 Syria*• 1264 Syria*• 1321/1322 Yemen• Nov 1370 Syria• 1422-23 Egypt• Aug 1449 Yemen• 1570-71 Spain
• * Suspected aurora
Ref: Basurah, Sol. Phys, 225,2005; JASTP, 68, 2006
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ITEMS NEEDED FOR COMPREHENSIVE STUDY OF HISTORIC EXTREME SOLAR-TERRESTRIAL EVENTS
● CONSOLIDATED MID AND LOW LATITUDE AURORA LIST
THESE DATA ARE CURRENTLY SCATTERED ALL OVER THE LITERATURE – IN BOOKS, ARCHIVES AND INDIVIDUAL PUBLICATIONS
● NAKED EYE SUNSPOT SIGHTINGS PRE 1700
● INDIVIDUAL MAGNETIC DISTURBANCE RECORDS
SHIP’S LOGS MAY PROVIDE SOME INSIGHT
CARE MUST BE TAKEN WITH THE DATES CITED IN THE ORIGINAL RECORDS.
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14C INCREASES – 774/775 AND 992/993
IF THESE INCREASES ARE THE RESULT OFA MASSIVE SOLAR PROTON EVENT, THERE MIGHT NOT HAVE BEEN A MAJOR GEOMAGNETIC DISTURBANCE OR LOW LATITUDE AURORA, ESPECIALLY IF THE SOLAR ACTIVITY WAS ON THE WEST LIMB OF THE SUN.
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