Ionospheric closure of small-scale Birkeland currents

Journal Article · Fri Feb 01 04:00:00 EST 1991 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/90JA02376· OSTI ID:5222814

Forget, B; Cerisier, J C; Berthelier, A; Berthelier, J J ^[1]

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1. Centre National de la Recherche Scientifique, Saint-Maur-des-Fosses (France)

In this paper, the authors study the relationship between the spatial variations of the perpendicular electric field observed in the topside ionosphere and those of the magnetic field induced by the associated field-aligned currents. The mapping of the magnetospheric electric field down to the ionosphere depends upon the spatial scale of its variations and consequently, also the amplitude of the perpendicular currents and their divergence. This mapping is modeled using realistic conductivity profiles, and the dependence of the electric and magnetic fields upon the spatial scale is analyzed. They compare the effective integrated Pedersen conductivity {Sigma}{sub p,eff} defined in the model to {Delta}B/{mu}{sub o}{Delta}E, where {Delta}E, where {Delta}E and {Delta}B are the correlated variations of the mutually orthogonal electric and magnetic fields in the topside ionosphere. They have studied the variation of {Sigma}{sub p,eff} as a function of the scale of {Delta}E and {Delta}B fluctuations. {Sigma}{sub p,eff} is constant and equal to the classical integrated Pedersen conductivity for scales larger than {approx} 5km. At smaller scales, it shows a steep decrease down to the lowest scales considered of 0.1 km. The good agreement between observations made on board the AUREOL 3 satellite and this model calculation suggests that the ULF electromagnetic turbulence observed frequently in the cusp and auroral zone may be essentially due to the crossing of spatially structured field-aligned currents. The limits of the present model and its possible improvements are discussed.

• OSTI ID: 5222814
• Journal Information: Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Vol. 96:A2; ISSN JGREA; ISSN 0148-0227
• Country of Publication: United States
• Language: English

Related Subjects

640201* -- Atmospheric Physics-- Auroral
Ionospheric
& Magetospheric Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
AURORAL ZONES
COMPARATIVE EVALUATIONS
CURRENTS
DISTRIBUTION
EARTH ATMOSPHERE
EARTH MAGNETOSPHERE
ELECTRIC CONDUCTIVITY
ELECTRIC CURRENTS
ELECTRIC FIELDS
ELECTRICAL PROPERTIES
EVALUATION
IONOSPHERE
MAPPING
MATHEMATICAL MODELS
PHYSICAL PROPERTIES
PLANETARY IONOSPHERES
POLAR CUSP
SATELLITES
SPATIAL DISTRIBUTION
TURBULENCE
VARIATIONS