Case study of plasma processes in the dayside cleft
The HILAT satellite moving approximately along the noon meridian passed over northeastern Canada and encountered the dayside high-latitude cleft. During the passage an upward current sheet bounded to the north and south by weaker downward current sheets was observed. The current sheets, particularly the upward current sheet, were immersed in a region of fairly intense low-energy electron precipitation of the type commonly observed in the polar cleft. Simultaneous radar measurements were made in a region slightly to the east of the satellite track and in which beacon measurements between HILAT and a ground station at Sondre Stromford, Greenland, were being conducted. The radar indicated an extended, magnetic east west aligned region of small-scale irregularities at the same magnetic latitude as the cleft-related current sheets and precipitation. The HILAT beacon experiment showed the strongest scintillations within the same region. On the basis of the available data, it appears as if the convective flows from the dawn and dusk sectors were converging and rotating poleward within the observational volume. The irregularities producing the scintillations and radar backscatter may have been produced by the combined influence of the gradient drift and current convective plasma instabilities, the former process being excited by the poleward convection of plasma parallel to the precipitation-induced density gradient and the latter process by the upward field-aligned current. The apparent absence of irregularities further into the polar cap may be accounted for by the stabilizing effect of plasma drift antiparallel to the density gradient on the poleward edge of the cleft precipitation zone.
- Research Organization:
- Johns Hopkins Univ., Laurel, MD (USA). Applied Physics Lab.
- OSTI ID:
- 5139923
- Report Number(s):
- AD-A-170500/3/XAB
- Country of Publication:
- United States
- Language:
- English
Similar Records
Low frequency modulation of plasmas and soft-electron precipitation near the dayside cusp. Scientific report No. 4, 19 June 1984-30 September 1986
Simultaneous radar and satellite observations of the polar cusp/cleft at Sondre Stromfjord. Interim scientific report
Related Subjects
GENERAL PHYSICS
AURORAE
ELECTRON PRECIPITATION
PLASMA DRIFT
POLAR REGIONS
ELECTRIC FIELDS
ELECTRON DENSITY
LATITUDE EFFECT
CHARGED-PARTICLE PRECIPITATION
GEOGRAPHICAL VARIATIONS
VARIATIONS
640201* - Atmospheric Physics- Auroral
Ionospheric
& Magetospheric Phenomena