Ionospheric convection response to slow, strong variations in a northward interplanetary magnetic field: A case study for January 14, 1988

Journal Article · Mon Nov 01 04:00:00 EST 1993 · Journal of Geophysical Research

DOI:https://doi.org/10.1029/93JA01010· OSTI ID:146562

Knipp, D J; Emery, B A; Richmond, A D ^[1]

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1. High Altitude Observatory, NCAR, Boulder, CO (United States); and others

The authors analyze ionospheric convection patterns over the polar regions during the passage of an interplanetary magnetic cloud on January 14, 1988, when the interplanetary magnetic field (IMF) rotated slowly in direction and had a large amplitude. Using the assimilative mapping of ionospheric electrodynamics (AMIE) procedure, they combine simultaneous observations of ionospheric drifts and magnetic perturbations from many different instruments into consistent patterns of high-latitude electrodynamics, focusing on the period of northward IMF. By combining satellite data with ground-based observations, the authors have generated one of the most comprehensive data sets yet assembled and used it to produce convection maps for both hemispheres. They present evidence that a lobe convection cell was embedded within normal merging convection during a period when the IMF B{sub y} and B{sub z} components were large and positive. As the IMF became predominantly northward, a strong reversed convection pattern (afternoon-to-morning potential drop of around 100 kV) appeared in the southern (summer) polar cap, while convection in the northern (winter) hemisphere became weak and disordered with a dawn-to-dusk potential drop of the order of 30 kV. These patterns persisted for about 3 hours. They interpret this behavior in terms of a recently proposed merging model for northward IMF under solstice conditions, for which lobe field lines from the hemisphere tilted toward the Sun (summer hemisphere) drape over the dayside magnetosphere, producing reverse convection in the summer hemisphere and impeding direct contact between the solar wind and field lines connected to the winter polar cap. The various convection patterns derived under northward IMF conditions illustrate all possibilities previously discussed in the literature: nearly single-cell and multicell, distorted and symmetric, ordered and unordered, and sunward and antisunward. 76 refs., 9 figs.

• Sponsoring Organization: USDOE
• OSTI ID: 146562
• Journal Information: Journal of Geophysical Research, Journal Name: Journal of Geophysical Research Journal Issue: A11 Vol. 98; ISSN JGREA2; ISSN 0148-0227
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
CONVECTION
ELECTRIC FIELDS
ELECTRODYNAMICS
INTERPLANETARY MAGNETIC FIELDS
IONOSPHERE
POLAR REGIONS