Effects of high-latitude conductivity on observed convection electric fields and Birkeland currents

Journal Article · Mon Dec 01 04:00:00 EST 1980 · J. Geophys. Res.; (United States)

DOI:https://doi.org/10.1029/JA085iA12p06811· OSTI ID:6680681

Smiddy, M; Burke, W J; Kelley, M C; Saflekos, N A; Gussenhoven, M S; Hardy, D A; Rich, F J

Relationships between convective electric fields, Birkeland currents, and ionospheric conductivity at high latitudes are investigated by using simultaneous measurements of electric and magnetic fields and electron fluxes from the S3-2 satellite. Cases in which the polar cap is in sunlight and darkness are studied to assess the importance of ionospheric conductivity. We find that when the ionophereic conductivity is high, as it normally is in the auroral zones and the sunlit polar cap, Birkeland current sheets exist that deflect the magnetic field approximately in the direction of the convection, typically antisunward in the polar caps and sunward in the auroral zones. Under winter conditions (a dark polar ionosphere), no large-scate antisunward deflection of magnetic field lines is found in the polar cap. Magnetic field defections in the auroral zone are the result of the region 1/region 2 current system discussed by Iijima and Potemra (1976). In the cases studied, region 1 currents are not observed to extend significantly poleward of the electric field reversal. We interpret this result as indicating the existence of strong conductivity gradients near the poleward boundary of the auroral oval, even in sunlight conditions. Deflections of magnetic field lines in the summer polar cap, first reported by McDiarmid et al. (1979), result from currents which serve to link the high-latitude generator to the polar ionosphere load. Two types of linkage appear in the data; (1) Region 1 currents are greater than region 2 currents, with the excess region 1 current flowing across the polar cap from dawn to dusk. (2) An extra set of field-aligned currents exist which are clearly detached from those of region 1 and are entirely poleward of the convective electric field reversal. We find that the evidence for antisunward convection on closed field lines threading the boundary layer, cited by McDiarmid et al. (1978), is inconclusive.

• Research Organization: Air Force Geophysics Laboratory, Hanscom Air Force Base, Massachusetts 01731
• OSTI ID: 6680681
• Journal Information: J. Geophys. Res.; (United States), Journal Name: J. Geophys. Res.; (United States) Vol. 85:A12; ISSN JGREA
• 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
BOUNDARY LAYERS
CHARGED-PARTICLE PRECIPITATION
CURRENTS
DATA
EARTH ATMOSPHERE
ELECTRIC CONDUCTIVITY
ELECTRIC CURRENTS
ELECTRIC FIELDS
ELECTRICAL PROPERTIES
ELECTRON PRECIPITATION
EXPERIMENTAL DATA
INFORMATION
IONOSPHERE
LAYERS
MAGNETIC FIELD CONFIGURATIONS
MAGNETOSPHERE
NUMERICAL DATA
PHYSICAL PROPERTIES
PLANETARY IONOSPHERES
PLASMA SHEET