Observations of solar-wind-driven modulation of the dayside ionospheric DPY current system

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

DOI:https://doi.org/10.1029/94JA01193· OSTI ID:207222

Clauer, C R; Miller, P M; Sitar, R J ^[1]

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1. Univ. of Michigan, Ann Arbor, MI (United States); and others

The authors report here a collection of complementary measurement near local magnetic noon of a unique ionospheric convection variation observed by the Sondrestrom radar which is related to a nearly periodic variation ({approx} 25-30 min period) in the interplanetary magnetic field B{sub y} component. The authors observe also a poleward phase propagation of magnetic pulsations over a region limited in longitude and latitude near the dayside polar cusp. A series of poleward propagating radio absorption enhancements are observed in the Greenland and South Pole imaging riometer data. The pulsations and absorption enhancements are associated with latitudinally narrow and longitudinally limited intensifications of the westward convection and associated eastward Hall current, which propagates poleward over the magnetometers and radar field of view. For the cases presented the interplanetary B{sub z} is strongly negative, while the ionospheric variations are associated with the low-frequency component of variations in the interplanetary B{sub y} component. In contrast to the previously discovered traveling convection vortices, these features exhibit a poleward phase motion rather than one along lines of invariant latitude. The propagation velocity is slower ({approx} 0.5 - 1.0 km/s) and the structures cover 2 to 3 hours of local time. The authors interpret the observations as a poleward propagation of the DPY current system intensification associated with enhancements in the IMF B{sub y} component. Their observations indicate that the DPY field-aligned current system is propagating poleward and may be moving independent of the convection motion of the plasma and associated field lines. 51 refs., 14 figs., 1 tab.

• OSTI ID: 207222
• 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
CONVECTION
CORRELATIONS
ELECTRIC CURRENTS
INTERPLANETARY MAGNETIC FIELDS
IONOSPHERE
MODULATION
POLAR CUSP
PULSES
SOLAR WIND