Numerical modelling of intermittent ion outflow events above EISCAT

• Published in: Journal of atmospheric and terrestrial physics 1996, Vol.58 (1), p.273-285
• Main Authors: Blelly, P.L., Robineau, A., Alcaydé, D.
• Format: Article
• Language: English
• ISSN: 0021-9169
• DOI: 10.1016/0021-9169(95)00035-6

EISCAT observations with the UHF and VHF radars of the dynamics of the upper ionosphere have revealed the occurrence of intermittent ion outflows with velocities reaching several hundred m s −1. It was previously shown that, during such events, the topside downward electron heat flux, inferred from the analysis of the vertical (field-aligned) structure of the electron temperature profiles, increases drastically up to values of about 10 μW m −2. The numerical models described in a companion paper are used here to simulate the effects of energy inputs driven by the magnetosphere. Three main effects are simulated separately: effects of frictional heating related to E × B drifts, effects due to topside heat flux perturbations and effects of upward field-aligned currents of a few tens of μA m −2. It is shown that field-aligned currents and topside heat flux perturbations produce very similar effects and that combining field-aligned currents with frictional heating allows us to model the overall characteristics of the perturbations of the electron density, of the electron and ion temperatures, and of the ion vertical velocity. A good agreement with observations is found.