 |
| Titel |
The ring current: a short biography |
| VerfasserIn |
A. Egeland, W. J. Burke |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
2190-5010
|
| Digitales Dokument |
URL |
| Erschienen |
In: History of Geo- and Space Sciences ; 3, no. 2 ; Nr. 3, no. 2 (2012-08-06), S.131-142 |
| Datensatznummer |
250001016
|
| Publikation (Nr.) |
 copernicus.org/hgss-3-131-2012.pdf |
|
|
|
|
|
| Zusammenfassung |
| The "ring current'' grows in the inner magnetosphere during magnetic storms
and contributes significantly to characteristic perturbations to the Earth's
field observed at low-latitudes. This paper outlines how understanding of
the ring current evolved during the half-century intervals before and after
humans gained direct access to space. Its existence was first postulated in
1910 by Carl Størmer to explain the locations and equatorward migrations
of aurorae under stormtime conditions. In 1917 Adolf Schmidt applied
Størmer's ring-current hypothesis to explain the observed negative
perturbations in the Earth's magnetic field. More than another decade would
pass before Sydney Chapman and Vicenzo Ferraro argued for its necessity to
explain magnetic signatures observed during the main phases of storms. Both
the Størmer and Chapman–Ferraro models had difficulties explaining how
solar particles entered and propagated in the magnetosphere to form the ring
current. During the early 1950s Hannes Alfvén correctly argued that the
ring current was a collective plasma effect, but failed to explain particle
entry. The discovery of a weak but persistent interplanetary magnetic field
embedded in a continuous solar wind provided James Dungey with sufficient
evidence to devise the magnetic merging-reconnection model now regarded as
the basis for understanding magnetospheric and auroral activity. In the
mid-1960s Louis Frank showed that ions in the newly discovered plasma sheet
had the energy spectral characteristics needed to explain the ring current's
origin. The introduction of ion mass spectrometers on space missions during
the 1970s revealed that O+ ions from the ionosphere contribute large
fractions of the ring current's energy content. Precisely how cold O+ ions
in the ionosphere are accelerated to ring-current energies still challenges
scientific understanding. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|