Convection and field-aligned currents, related to polar cap arcs, during strongly northward IMF (11 January 1983)

P. L. Israelevich, I. M. Podgorny, A. K. Kuzmin, N. S. Nikolaeva, E. M. Dubinin

Research output: Contribution to journalArticlepeer-review

Abstract

Electric and magnetic fields and auroral emissions have been measured by the Intercosmos-Bulgaria-1300 satellite on 10-11 January 1983. The measured distributions of the plasma drift velocity show that viscous convection is diminished in the evening sector under IMF By < 0 and in the morning sector if IMF By > 0. A number of sun-aligned polar cap arcs were observed at the beginning of the period of strongly northward IMF and after a few hours a θ-aurora appeared. The intensity of ionized oxygen emission [O+(2P), 7320 Å] increased significantly reaching up to several kilo-Rayleighs in the polar cap arc. A complicated pattern of convection and field-aligned currents existed in the nightside polar cap which differed from the four-cell model of convection and NBZ field-aligned current system. This pattern was observed during 12 h and could be interpreted as six large scale field-aligned current sheets and three convective vortices inside the polar cap. Sun-aligned polar cap arcs may be located in regions both of sunward and anti-sunward convection. Structures of smaller spatial scale correspond to the boundaries of hot plasma regions related to polar cap arcs. Obviously these structures are due to S-shaped distributions of electric potential. Parallel electric fields in these S-structures provide electron acceleration up to 1 keV at the boundaries of polar cap arcs. The pairs of field-aligned currents correspond to those S-structures: a downward current at the external side of the boundary and an upward current at the internal side of it.

Original languageEnglish
Pages (from-to)1317-1328
Number of pages12
JournalPlanetary and Space Science
Volume36
Issue number12
DOIs
StatePublished - Dec 1988
Externally publishedYes

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