Abstract
Abstract. We present two event studies encompassing detailed relationships between plasma convection, field-aligned current, auroral emission, and particle precipitation boundaries. We illustrate the influence of the Interplanetary Magnetic Field By component on theta aurora development by showing two events during which the theta originates on both the dawn and dusk sides of the auroral oval. Both theta then move across the entire polar region and become part of the opposite side of the auroral oval. Electric and magnetic field and precipitating particle data are provided by DMSP, while the Polar UVI instrument provides measurements of auroral emissions. Utilizing satellite data as inputs, the Royal Institute of Technology model provides the high-latitude ionospheric electrostatic potential pattern calculated at different times during the evolution of the theta aurora, resulting from a variety of field-aligned current configurations associated with the changing global aurora. Key words. Ionosphere (auroral ionosphere; electric fields and currents). Magnetospheric physics (magnetosphereionosphere interactions)
Highlights
High-latitude auroral arcs are often observed on the dawn and dusk sides of the auroral oval during northward Interplanetary Magnetic Field (IMF), of these, rare cases of theta aurora are seen where the transpolar arcs (TPAs) move across the entire polar region
The high-latitude convection pattern is dominated by sunward flow, some of which can be closed in the duskside anti-sunward flow region, producing anti-clockwise circulation in a cell located at highest latitudes on the duskside of the polar region
In this paper we have attempted to reconstruct the ionospheric electrodynamical state associated with the evolution of theta aurora originating from both the dawn and the dusk sides of the auroral oval
Summary
High-latitude auroral arcs are often observed on the dawn and dusk sides of the auroral oval during northward Interplanetary Magnetic Field (IMF), of these, rare cases of theta aurora are seen where the transpolar arcs (TPAs) move across the entire polar region. Distorted two-cell (Robinson and Mende, 1990; Marklund et al, 1991) These studies are based on single observations of TPAs and represent different stages of theta aurora evolution, depending on different IMF Bx and By conditions during northward IMF. A model study of the relationship between the large-scale convection pattern and the transpolararc associated field-aligned currents was performed by. During each event a variety of field-aligned current configurations is observed, associated with the changing global aurora
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