Seasonal variations of the ionospheric E x B drifts above Saint-Santin on quiet days

Journal Article · Fri Jun 01 04:00:00 EDT 1979 · J. Geophys. Res.; (United States)

DOI:https://doi.org/10.1029/JA084iA06p02691· OSTI ID:6130002

Blanc, M; Amayenc, P

A seasonal model of the F region electric-field-induced plasma drifts prevailing during magnetically quiet periods, and of their day-to-day variability, has been established on the basis of 3 years of measurements (1973--1975) above Saint-Santin (44/sup 0/ 39'N, 2/sup 0/ 12'E) with the French quadristatic incoherent scatter facility. It is expressed analytically with the help of a steady component and of the first four diurnal harmonic oscillations and can be used both as a base line for magnetospheric disturbance studies and in itself as a source of information on the morphology of ionospheric wind dynamo electric fields. For all seasons these drifts appear to be dominated by a semidiurnal oscillation in the north-south direction and by a diurnal one in the east-west direction. During the daytime the flow is northwestward in the morning and then southeastward in the afternoon. Seasonal effects are dominated by a marked contrast between summer and the two other seasons. Summer is characterized by a disappearance of the morning northward drifts and a more complex harmonic content of the east-west drifts, with a larger contribution of the secondary semidiurnal and terdiurnal components. Comparison with recent dynamo calculations shows an improved agreement on the north-south component of the drifts, even though it still leaves a significant gap between theory and experiment. The results provide evidence that the attempt to realize a good theory/experiment coincidence meets several difficulties of a fundamental nature: one is the lack of a simple summer/winter symmetry in the observed drifts, which reveals the importance of longitude effects introduced by the real earth's magnetic field; another is the large day-to-day variability within each season, which is comparable to the diurnal amplitude itself. Both show the need of worldwide coordinated efforts for the acquisition of simultaneous incoherent scatter data as well as for their interpretation.

• Research Organization: Centre de Recherche en Physique de l'Environnement, Etudes pur Teledetection de l'Environnement, Issy-les-Moulineaux, France
• OSTI ID: 6130002
• Journal Information: J. Geophys. Res.; (United States), Journal Name: J. Geophys. Res.; (United States) Vol. 84:A6; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

640201* -- Atmospheric Physics-- Auroral
Ionospheric
& Magetospheric Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
CURRENTS
DAILY VARIATIONS
EARTH ATMOSPHERE
ELECTRIC CURRENTS
ELECTRIC FIELDS
F REGION
INCOHERENT SCATTERING
IONOSPHERE
PLANETARY IONOSPHERES
PLASMA DRIFT
SCATTERING
SEASONAL VARIATIONS
VARIATIONS
WAVE PROPAGATION