Magnetospheric processes preceding the onset of an isolated substorm: A case study of the March 31, 1978, substorm

Journal Article · Thu Sep 01 04:00:00 EDT 1983 · J. Geophys. Res.; (United States)

DOI:https://doi.org/10.1029/JA088iA09p07005· OSTI ID:5470575

Nishida, A; Kamide, Y

We examined in detail the effect of a southward turning of the interplanetary magnetic field (IMF) on the state of the magnetosphere, taking advantage of the availability of the data from IMS magnetometer meridian chains and from several spacecraft. A clear onset substorm occurred on March 31, 1978, when the magnetometer stations were located in the midnight to morning sector and the spacecraft were near the equatorial plane of the nightside magnetosphere. The onset time of the substorm expansion phase could be determined unambiguously in terms of both ground-based magnetic and auroral signatures, and there was an interval lasting about 1 hour between the IMF southward turning and this onset. In this intervening interval the ionospheric current system of the DP 2 type developed. This enhancement of the ionospheric current was driven directly by the solar wind-magnetosphere coupling. The onset of the expansion phase was then associated with the decrease in the magnetic field energy density in the tail, providing evidence that the substorm energy was supplied by the release (unloading) of energy from the tail. It is most likely that substorm energy dissipated in the auroral ionosphere throughout this relatively isolated and simple event was supplied by two components, 'directly driven' and 'loading-unloading,' the relative importance of which varied depending on the different substorm phases.

• Research Organization: Institute of Space and Astronautical Science
• OSTI ID: 5470575
• Journal Information: J. Geophys. Res.; (United States), Journal Name: J. Geophys. Res.; (United States) Vol. 88:A9; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

640203* -- Atmospheric Physics-- Magnetospheric Phenomena-- (-1987)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
AURORAL ZONES
CURRENTS
EARTH ATMOSPHERE
ELECTRIC CURRENTS
ENERGY DENSITY
GEOMAGNETIC FIELD
INTERPLANETARY MAGNETIC FIELDS
IONOSPHERE
MAGNETIC BAYS
MAGNETIC FIELDS
MAGNETOSPHERE
MAGNETOTAIL
PLANETARY IONOSPHERES