Transcript 14C increase in 775 and 993 AD

14C
increase
775 and 993 AD:
Aurora observations in ancient
times.
M. A. Shea
Jull et al., 2014
Possible explanations:
Extreme Solar Proton Event
Comet Collision - January 773
Gamma-ray Burst – Super Nova
HOW CAN OUR MODERN
KNOWLEDGE
HELP IN THE UNDERSTANDING
OF HISTORICAL PHENOMENA?
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)
SOLAR AND GEOMAGNETIC DATA-SELECTED EVENTS
EVENT
SOLAR
ACTIVITY
GLE
GMS
AA*
INDEX
RANK
22 Mar 91
10 Mar 89
25 Jul 46
28 Feb 42
21 May 90
19 Nov 49
23 Feb 56
7 Mar 42
29 Sep 89
28 E
22 E
15 E
4 E
37 W
72 W
80 W
90 W
105 W
No
No
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
No
Yes
No
No
176
441
329
168
74
1
11
80
131
166
5 Oct 60
N/A
No
Yes
253
28
AA* Index: 1868-2010
THINGS WE HAVE LEARNED:
MAJOR SPEs FROM CENTRAL MERIDIAN ACTIVITY
GENERALLY 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.
CAN IDENTIFICATION OF LOW LATITUDE
AURORA HELP TO RESOLVE UNUSUAL
GEOPHYSICAL RECORDS SUCH AS 14C
INCREASES IN TREE RINGS?
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
CHANGE IN MAGNITUDE OF THE G(1,0) TERM
OF THE EARTH’S MAGNETIC FIELD, 1600-2010
(18% decrease in 400 years)
CHANGES IN THE POSITION OF THE EARTH’S DIPOLE
1000 AD – 2000 AD
CHANGES IN THE POSITION OF THE EARTH’S DIPOLE
0 AD TO 1990 AD
EXAMPLES OF GEOMAGNETIC LATITUDE
CHANGES
LOCATION
1000
2000
CHANGE
S. SPAIN
SAN DIEGO
CHICAGO
EGYPT
TASMANIA
35° N
25° N
36° N
34° N
38° S
40° N
40° N
51° N
28° N
50° S
5° N
15° N
15° N
6° S
12° S
(VALUES ARE APPROXIMATE)
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
May 1179
Nov 1203
1223
1264
1321/1322
Nov 1370
1422-23
Aug 1449
1570-71
Syria*
Syria
Yemen
Syria*
Syria*
Yemen
Syria
Egypt
Yemen
Spain
• * Suspected aurora
Ref: Basurah, Sol. Phys, 225,2005; JASTP, 68, 2006
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.
14C
INCREASES – 774/775 AND 992/993
IF THESE INCREASES ARE THE RESULT OF
A 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.