Quantitative patterns of large-scale field-aligned currents in the auroral ionosphere

Journal Article · Wed Mar 01 04:00:00 EST 1989 · J. Geophys. Res.; (United States)

DOI:https://doi.org/10.1029/JA094iA03p02555· OSTI ID:6457272

Foster, J C; Fuller-Rowell, T; Evans, D S

Quantitative patterns of the distribution of field-aligned current (FAC) density have been derived from gradients of the average patterns of the Hall and Pedersen currents at high latitudes under the assumption that the total current is divergence-free. The horizontal currents were calculated from empirical convection electric field models, derived from Millstone Hill radar observations, and the ionospheric Hall and Pedersen conductances, based on satellite observations of the precipitating particle energy flux and spectrum and including an average (equinox) solar contribution. These independent empirical models, and the resultant patterns of the field-aligned currents, are keyed to an auroral precipitation index which quantifies the intensity and spatial extent of high-latitude particle precipitation and which is determined from a single satellite crossing of the auroral precipitation pattern. The patterns detail the spatial distribution of the currents as a function of increasing disturbance level. The magnitudes of the total single-hemisphere currents into or out of the ionosphere are closely balanced at each activity level and increase exponentially between 0.1 and 6 MA with increasing values of the precipitation index. The interplanetary magnetic field (IMF) sector dependence of the FAC patterns is investigated for disturbed conditions. A large portion of the FAC pattern is closed by local Pedersen currents (current into the ionosphere is balanced by an equal current out of the ionosphere at that local time). This locally balanced portion of the FAC system is enhanced in the prenoon (postnoon) sector for IMF B/sub v/>+1 nT (B/sub y/<-1 nT). In addition, there are net currents into the ionosphere postnoon and out of the ionosphere in the premidnight sector.

• Research Organization: Atmospheric Sciences Group, Haystack Observatory, Massachusetts Institute of Technology, Westford, Massachusetts
• OSTI ID: 6457272
• Journal Information: J. Geophys. Res.; (United States), Journal Name: J. Geophys. Res.; (United States) Vol. 94:A3; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

640201* -- Atmospheric Physics-- Auroral
Ionospheric
&amp; Magetospheric Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
AURORAL ZONES
CHARGED-PARTICLE PRECIPITATION
CONVECTION
CURRENTS
DAILY VARIATIONS
EARTH ATMOSPHERE
ELECTRIC CURRENTS
ELECTRIC FIELDS
ENERGY TRANSFER
HEAT TRANSFER
INTERPLANETARY MAGNETIC FIELDS
IONOSPHERE
MAGNETIC FIELDS
MASS TRANSFER
MATHEMATICAL MODELS
PLANETARY IONOSPHERES
VARIATIONS