Modeling substorm current sytems using conductivity distributions inferred from DE (Dynamics Explorer) auroral images

Technical Report · Wed Oct 01 04:00:00 EDT 1986

OSTI ID:7060188

Kamide, Y; Craven, J D; Frank, L A; Ahn, B H; Akasofu, S I

Images of auroral emissions observed with Dynamics Explorer 1 (DE 1) are used to calculate ionospheric conductivities over the polar region. The combination of ground-based magnetometer data and the inferred conductivities estimate, on a global scale, the distributions of ionosphere electric fields and currents and field-aligned currents, as well as the Joule-heating production rate, with a time resolution of 12 min. Although the inference of the conductivity distribution requires further improvements, the following conclusions may be drawn from this work: (1) The westward electrojet is in general collocated with the region of high auroral luminosity while the region of relatively low luminosity in the evening sector is collocated with the eastward electrojet. (2) The upward field-aligned currents exist in the brightest auroral region on the poleward side of the evening auroral oval and on the equatorward side of the morning oval. However, the magnitudes of these upward currents are not in proportion to the auroral luminosities, suggesting that the characteristic energies of precipitating electrons carrying the upward currents and generating the auroral luminosities may be different. (3) A significant amount of ionospheric currents can flow in regions where there are no bright auroral emissions. An example of this effect is found over the poleward half of the westward electrojet in the morning sector where the electric field is the main contributor to the ionospheric currents. (4) The distribution of calculated field-aligned currents displays many localized structures that characterize the development of the substorm current system.

• Research Organization: Iowa Univ., Iowa City (USA). Dept. of Physics and Astronomy
• OSTI ID: 7060188
• Report Number(s): AD-A-175730/1/XAB
• Country of Publication: United States
• Language: English

Related Subjects

640201* -- Atmospheric Physics-- Auroral
Ionospheric
& Magetospheric Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ALIGNMENT
AURORAE
CHARGED-PARTICLE PRECIPITATION
CURRENTS
DISTRIBUTION
EARTH ATMOSPHERE
ELECTRIC CURRENTS
ELECTRIC FIELDS
ELECTROJETS
ELECTRON PRECIPITATION
HEATING
IMAGES
IONOSPHERE
LUMINOSITY
MAGNETIC STORMS
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
PLANETARY IONOSPHERES
POLAR REGIONS
POLAR-CAP AURORAE