Cusp currents from ionospheric vorticity generated by gasdynamic and merging flow fields at the magnetopause

Journal Article · Mon May 01 04:00:00 EDT 1995 · Journal of Geophysical Research

DOI:https://doi.org/10.1029/94JA03370· OSTI ID:207218

Mie, Y ^[1]; Crooker, N U; Siscoe, G L ^[2]

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1. Univ. of California, Los Angeles, CA (United States)
2. Boston Univ., MA (United States)

Cusp currents that arise from ionospheric vorticity generated by the combined merging outflow and gasdynamic flow fields at the magnetopause are quantified and compared with those calculated from vorticity generated by mapping the solar wind electric field into a limited cusp region of the polar cap, as proposed in the synthesis view of Banks. The results are essentially identical for strong interplanetary magnetic field (IMF) B{sub Y}, thus demonstrating equivalence between mechanical and electrical descriptions of reconnection-driven convection. For southward IMF, however, the mechanical description yields weak cusp currents with dawn-dusk bipolarity, as deduced from early observations by Iijima and Potemra, whereas the electrical description yields none. The bipolar currents arise from the diverging pattern of gasdynamic flow. The currents become unipolar as B{sub Y} increases and the asymmetry of the merging outflow dominates. Additional cusp currents in both models arise at kinks in the flow contours (additional ionospheric vorticity) around the border of the cusp region, owing to limiting the area of mapping from the magnetopause. The border currents form a bipolar pair that rotates around the circumference of the cusp as the IMF rotates in clock angle. They dominate the currents arising from vorticity within the cusp. 17 refs., 3 figs.

• OSTI ID: 207218
• Journal Information: Journal of Geophysical Research, Journal Name: Journal of Geophysical Research Journal Issue: A5 Vol. 100; ISSN JGREA2; ISSN 0148-0227
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
ELECTRIC CURRENTS
INTERPLANETARY MAGNETIC FIELDS
MAGNETIC FLUX
MAGNETIC RECONNECTION
MAGNETOPAUSE
POLAR CUSP
VORTICES