Magnetic field configuration of the theta aurora

Journal Article · Sun Apr 01 04:00:00 EDT 1990 · Geophysical Research Letters (American Geophysical Union); (USA)

DOI:https://doi.org/10.1029/GL017i005p00595· OSTI ID:6785094

Toffoletto, F R; Hill, T W ^[1]

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1. Rice Univ., Houston, TX (USA)

The theta aurora is an approximately Sun-aligned transpolar arc that often extends the entire length of the polar cap, linking the dayside and nightside auroral zones. It is a remarkable manifestation of polar cap auroral activity that appears during periods of northward interplanetary magnetic field (IMF). In this paper the authors describe a magnetic configuration of the open magnetosphere that is conducive to the formation of the theta aurora when the IMF has a significant northward component. They present a magnetic field topology and polar cap configuration that is derived from a quantitative model of the open magnetosphere that incorporates Crooker's antiparallel merging hypothesis. Under this hypothesis, when the IMF has a northward component, the dayside merging line bifurcates, leaving a large fraction of the subsolar magnetopause untouched by the merging process. The polar cap, defined by tracing magnetic field lines that connect from the solar wind to the Earth, is similarly bifurcated, leaving a sun-aligned stagnation region that is not magnetically connected to the solar wind and may plausibly be associated with the sun-aligned bar of the theta aurora. The model provides testable predictions with regard to the position of this convection gap in both northern and southern hemispheres as functions of IMF direction.

• OSTI ID: 6785094
• Journal Information: Geophysical Research Letters (American Geophysical Union); (USA), Journal Name: Geophysical Research Letters (American Geophysical Union); (USA) Vol. 17:5; ISSN 0094-8276; ISSN GPRLA
• Country of Publication: United States
• Language: English

Related Subjects

640201* -- Atmospheric Physics-- Auroral
Ionospheric
& Magetospheric Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
AURORAE
AURORAL ZONES
CONVECTION
EARTH ATMOSPHERE
EARTH MAGNETOSPHERE
ENERGY TRANSFER
HEAT TRANSFER
INTERACTIONS
INTERPLANETARY MAGNETIC FIELDS
MAGNETIC FIELD CONFIGURATIONS
MAGNETIC FIELDS
MAGNETOPAUSE
MASS TRANSFER
MATHEMATICAL MODELS
POLAR REGIONS
SOLAR ACTIVITY
SOLAR WIND