|
|
 |
|
|
Ann. Geophys., 14, 1284-1296, 1996
www.ann-geophys.net/14/1284/1996/
© European Geosciences Union 1996
Large-scale distributions of ionospheric horizontal and field-aligned currents inferred from EISCAT
D. Fontaine and C. Peymirat
CETP-CNRS, Centre Universitaire, 10-12 Avenue de l'Europe, 78140 Vélizy, France
Abstract. Statistical models for large-scale convection
and for ionospheric conductances were previously derived from observations of
the incoherent-scatter radar EISCAT. We complete this large-scale description
with statistical models of the horizontal and field-aligned currents achieved
from the same data base and for the same ranges of the magnetic activity index Kp.
Except for the high-latitude dayside currents generally located poleward of the
radar field of view, a large part of the whole current system can be probed with
EISCAT. Globally consistent with previously published models, our results also
exhibit some differences, such as the asymmetry in the local-time extension of
the current sheets, concentrated to a few hours around 18 MLT in the evening
sector, while widely spread from premidnight to prenoon magnetic local times on
the morningside. This statistical description of the current system above EISCAT
allowed us to examine several aspects of the large-scale auroral
electrodynamics, namely the relationships between convection, conductances, and
currents, in particular in the vicinity of the Harang discontinuity, and the
features of the global current circuit.
Full Article in PDF (572 KB) |
|
|
