Field line equipotentiality and ion neutral collision frequencies in the dynamo region deduced from Saint-Santin ion drift measurements

Journal Article · Sat Aug 01 00:00:00 EDT 1981 · J. Geophys. Res.; (United States)

DOI:https://doi.org/10.1029/JA086iA08p06843· OSTI ID:5798464

Taieb, C; Blanc, M

We analyze three-dimensional ion drift data from the Saint-Santin incoherent scatter facility to test experimentally the theoretical description of ion transport in the ionospheric dynamo layer, and to deduce electric fields and ion neutral collision frequencies from the observed drifts. Using a geometrical representation of the ion momentum equation, we show that at middle latitudes, because horizontal neutral wind influences ion motions both parallel and orthogonal to the field lines in the ionospheric dynamo layer, the information contained in a three-dimensional ion drift measurement is redundant, thus permitting to check the standard theoretical description of ionospheric electrodynamics in two ways. First, assuming a model ion-neutral collision frequency profile, one can deduce the north-south perpendicular component of the electric field function of height in the E region from Saint-Santin drift data. We find that its altitude variations remain within the experimental uncertainty of the method, in agreement with the theoretical assumption of equipotential field lines. Second, assuming that the electric field is constant in altitude, one can determine the ion collision ratio, or ratio of the ion collision frequency to the ion gyrofrequency, from a comparison of E and F region drift measurements. Daily median values of the ion collision frequencies, thus obtained for each of the three seasons, are found to compare reasonably well with ion collision frequencies derived from the Jacchia neutral atmosphere model for the case of the equinox sample, but determinations for the other seasons are contaminated by a high level of measurement noise.

• Research Organization: CNET/Centre de Recherches en Physique de l'Environnement Terrestre et Planetaire, 92131 Issy-Les-Moulineaux, France
• OSTI ID: 5798464
• Journal Information: J. Geophys. Res.; (United States), Vol. 86:A8
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
IONOSPHERE
ION DRIFT
ELECTRIC FIELDS
ELECTRIC POTENTIAL
ION-MOLECULE COLLISIONS
SEASONAL VARIATIONS
THREE-DIMENSIONAL CALCULATIONS
WIND
COLLISIONS
EARTH ATMOSPHERE
ION COLLISIONS
MOLECULE COLLISIONS
PLANETARY IONOSPHERES
VARIATIONS
640201* - Atmospheric Physics- Auroral
Ionospheric
& Magetospheric Phenomena