 |
| Titel |
Toward a possible next geomagnetic transition? |
| VerfasserIn |
A. De Santis, E. Qamili, L. Wu |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1561-8633
|
| Digitales Dokument |
URL |
| Erschienen |
In: Natural Hazards and Earth System Science ; 13, no. 12 ; Nr. 13, no. 12 (2013-12-23), S.3395-3403 |
| Datensatznummer |
250085593
|
| Publikation (Nr.) |
 copernicus.org/nhess-13-3395-2013.pdf |
|
|
|
|
|
| Zusammenfassung |
| The geomagnetic field is subject to possible reversals or excursions of
polarity during its temporal evolution. Considering that: (a) in the last 83
million yr the typical average time between one reversal and the next (the
so-called chron) is around 400 000 yr, (b) the last reversal occurred
around 780 000 yr ago, (c) more excursions (rapid changes in polarity) can
occur within the same chron and (d) the geomagnetic field dipole is currently
decreasing, a possible imminent geomagnetic reversal or excursion would not
be completely unexpected. In that case, such a phenomenon would represent one
of the very few natural hazards that are really
global. The South Atlantic Anomaly (SAA) is a great depression of the
geomagnetic field strength at the Earth's surface, caused by a reverse
magnetic flux in the terrestrial outer core. In analogy with critical point
phenomena characterized by some cumulative
quantity, we fit the surface extent of this anomaly over the last 400 yr
with power law or logarithmic functions in reverse time, also decorated by
log-periodic oscillations, whose final singularity (a critical point
tc) reveals a great change in the near future
(2034 ± 3 yr), when the SAA area reaches almost a hemisphere. An
interesting aspect that has recently been found is the possible direct
connection between the SAA and the global mean sea level (GSL). That the GSL
is somehow connected with SAA is also confirmed by the similar result when an
analogous critical-like fit is performed over GSL: the corresponding critical
point (2033 ± 11 yr) agrees, within the estimated errors, with the
value found for the SAA. From this result, we point out the intriguing conjecture
that tc would be the time of no return, after which the
geomagnetic field could fall into an irreversible process of a global
geomagnetic transition that could be a reversal or excursion of polarity. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|