Development of auroral and geomagnetic substorm activity after a southward turning of the interplanetary magnetic field following several hours of magnetic calm

Journal Article · Tue Nov 01 04:00:00 EST 1977 · J. Geophys. Res.; (United States)

DOI:https://doi.org/10.1029/JA082i032p05031· OSTI ID:5400998

Lassen, K; Sharber, J R; Winningham, J D

A comprehensive study of growth phase and substorm activity following a period of magnetic calm has been conducted through a network of all-sky camera stations, auroral zone magnetic observatories, and particle detectors aboard the Isis 1 satellite. We have carefully documented the observations with the following results. The preexpansive phase are which extended at least from 17 to 05 MLT was responsible for an energy input rate of approx. =3 x 10/sup 16/ ergs/s before breakup. An equatorward drift of this arc of 6 km/min, observed only in the evening sector, remained until after the expansive phase, when its motion stopped abruptly at the time of the maximum poleward displacement of the arcs. Electrons responsible for the prebreakup arc had energies of approx. =1--5 keV. Protons of approx. =4-keV energy were measured equatorward of the electron arc. During the expansive phase, symmetrically traveling disturbances were observed propagating eastward in the evening sector and westward in the morning sector. The propagation stopped for 1--2 min at the time of maximum expansion and then continued, thus suggesting a momentary variation in the rate of convection. Equivalent currents consistent with observed magnetic perturbations represented approximately the same DPZ (twin vortex) pattern before the expansive phase as during it; however, although the magnitude of the currents was greater during the expansive phase, the dominant feature during this phase was an intense westward auroral electrojet. The camera observations of diffuse cloudlike aurora showed an injection of approx. =40-keV electrons during the expansive phase along the auroral oval between midnight and 0400 corrected geomagnetic time. Movement of the cloud indicated an eastward gradient drift of the electron population.

• Research Organization: Geophysics Section II, Danish Meteorological Institute, Copenhagen, Denmark 2100
• OSTI ID: 5400998
• Journal Information: J. Geophys. Res.; (United States), Journal Name: J. Geophys. Res.; (United States) Vol. 82:32; 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 OVAL
AURORAL ZONES
BARYONS
CURRENTS
ELECTRIC CURRENTS
ELECTROJETS
ELECTRONS
ELEMENTARY PARTICLES
ENERGY RANGE
FERMIONS
HADRONS
INTERPLANETARY MAGNETIC FIELDS
KEV RANGE
LEPTONS
MAGNETIC BAYS
MAGNETIC FIELDS
NUCLEONS
PROTONS