Ionospheric signatures of magnetospheric boundaries in the post-noon sector

Abstract. Spatial structures in ionospheric electron density revealed in a tomographic image have been identified with auroral forms and related to their sources in precipitating particles observed by DMSP satellites. The observations of plasma enhancements relate to discrete auroral arcs seen in the post-noon sector, identified by both red- and green-line emissions measured by a meridional scanning photometer. The features lie within a very narrow latitudinal band on L-shells where the satellite detectors observed electron precipitation classified as from the boundary plasma sheet (BPS). The harder particles are identified with an E-region structure, while further north the precipitation is softer, resulting in a localised F-layer blob and 630.0 nm emissions. A steep gradient in plasma density represent a signature in the ionosphere of the central plasma sheet (CPS)/BPS boundary. A transition to a less-structured F-layer is found on crossing the convection reversal boundary..Key words. Ionosphere (auroral ionosphere; ionosphere-magnetosphere interactions; polar ionosphere)

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Mapping of the statistical auroral distribution into the magnetosphere

Canadian Journal of Physics ◽

10.1139/p94-039 ◽

1994 ◽

Vol 72 (5-6) ◽

pp. 266-269 ◽

Cited By ~ 3

Author(s):

Y. I. Feldstein ◽

R. D. Elphinstone ◽

D. J. Hearn ◽

J. S. Murphree ◽

L. L. Cogger

Keyword(s):

Plasma Sheet ◽

Large Scale ◽

Source Region ◽

Central Plasma ◽

Discrete Structures ◽

Central Plasma Sheet ◽

Auroral Emissions ◽

Auroral Arcs ◽

Inner Region ◽

Entry Layer

Statistical auroral distributions are used in combination with an empirical model of the Earth's magnetic field in an attempt to determine the large-scale magnetospheric source regions for various types of auroral luminosity. The narrow ring of structured auroral emissions during magnetically quiet intervals appears to be associated with the inner region of the nightside central plasma sheet and the dayside entry layer. Under active conditions these discrete structures expand to fill the entire central plasma sheet. The high-altitude boundary plasma sheet on the other hand is more likely to be related to diffuse auroral emissions poleward of this "oval" and to high-latitude polar auroral arcs. Under this scenario, the region of the magnetosphere bounded by the inner edge of the tail current sheet, the plasmasphere, and the dayside entry layer is the source region for the most equatorward diffuse auroral precipitation.

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Travelling convection vortices in the ionosphere map to the central plasma sheet

Annales Geophysicae ◽

10.1007/s00585-996-1025-3 ◽

1996 ◽

Vol 14 (10) ◽

pp. 1025-1031 ◽

Cited By ~ 7

Author(s):

A. Yahnin ◽

T. Moretto

Keyword(s):

Boundary Layer ◽

Plasma Sheet ◽

Satellite Measurements ◽

Low Latitude ◽

Central Plasma ◽

Precipitation Boundary ◽

Boundary Plasma ◽

Central Plasma Sheet ◽

Low Altitude ◽

Low Latitude Boundary Layer

Abstract. We investigate the magnetospheric domain responsible for the generation of ionospheric travelling convection vortices (TCV) by comparing the location of the TCV to the locations of the low-altitude particle-precipitation boundaries deduced from the DMSP satellite measurements. For three very well documented TCV events we are able to identify suitable satellite passes, in the sense that for each event we can identify two to three passes occurring close to the TCV observation in both time and space. In all three cases the comparisons place the TCV centres at or equatorward of the central plasma sheet/boundary plasma sheet precipitation boundary. Thus our results indicate that the field-aligned currents related to the TCV originate in the plasma sheet rather than at the magnetopause or in the low-latitude boundary layer, as previous studies suggest.

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