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Titolo:
MIDTAIL PLASMA FLOWS AND THE RELATIONSHIP TO NEAR-EARTH SUBSTORM ACTIVITY - A CASE-STUDY
Autore:
LOPEZ RE; GOODRICH CC; REEVES GD; BELIAN RD; TAKTAKISHVILI A;
Indirizzi:
UNIV MARYLAND,DEPT ASTRON COLLEGE PK MD 20742 LOS ALAMOS NATL LAB LOS ALAMOS NM 00000 ABASTUMANI ASTROPHYS LAB TBILISI REP OF GEORGIA
Titolo Testata:
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
fascicolo: A12, volume: 99, anno: 1994,
pagine: 23561 - 23569
SICI:
2169-9380(1994)99:A12<23561:MPFATR>2.0.ZU;2-2
Fonte:
ISI
Lingua:
ENG
Soggetto:
ENERGETIC PARTICLE MEASUREMENTS; MAGNETIC-FIELD; CURRENT WEDGE; CURRENT DISRUPTION; SHEET; MAGNETOTAIL; EXPANSION; ONSET; MAGNETOSPHERE; RECONNECTION;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
40
Recensione:
Indirizzi per estratti:
Citazione:
R.E. Lopez et al., "MIDTAIL PLASMA FLOWS AND THE RELATIONSHIP TO NEAR-EARTH SUBSTORM ACTIVITY - A CASE-STUDY", J GEO R-S P, 99(A12), 1994, pp. 23561-23569

Abstract

Recent simulations of magnetotail reconnection have pointed to a linkbetween plasma flows, dipolarization, and the substorm current wedge. In particular, Hesse and Birn (1991) have proposed that earthward jetting of plasma from the reconnection region transports flux into the near-Earth region. At the inner edge of the plasma sheet this flux piles up, producing a dipolarization of the magnetic field. The vorticity produced by the east-west deflection of the flow at the inner edge of the plasma sheet gives rise to field-aligned currents that have region1 polarity. Thus in this scenario the earthward flow from the reconnection region produces the dipolarization and the current wedge in a self-consistent fashion. In this study we examine observations made on April 8, 1985 by the Active Magnetospheric Particle Tracer Explorers/Ion Release Module (IRM), the geosynchronous satellites 1979-053, 1983-019, and 1984-037, and Syowa station, as well as AE. This event is unique because IRM was located near the neutral sheet in the midnight sector for an extended period of time. Ground data show that there was ongoing activity in the IRM local time sector for several hours, beginning at 1800 UT and reaching a crescendo at 2300 UT. This activity was also accompanied by energetic particle variations, including injections,at geosynchronous orbit in the nighttime sector. Significantly, therewere no fast flows at the neutral sheet until the great intensification of activity at 2300 UT. At that time, IRM recorded fast earthward flow simultaneous with a dipolarization of the magnetic field. We conclude that while the aforementioned scenario for the creation of the current wedge encounters serious problems explaining the earlier activity, the observations at 2300 UT are consistent with the scenario of Hesse and Birn (1991). On that basis it is argued that the physics of substorms is not exclusively rooted in the development of a global tearingmode. Processes at the inner edge of cross-tail current that cause a disruption of the current and a consequent dipolarization and current wedge may be unrelated to the formation of a macroscale reconnection region. Thus the global evolution of a substorm is probably a complicated superposition of such processes operating on a very localized scaleand a global macroscale process that allows for such things as releasing the energy stored in lobe flux and the creation of plasmoids.

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Documento generato il 05/12/20 alle ore 13:54:39