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Zhang et al. 2004
Zhang, B., Kamide, Y., Liu, R., Shinagawa, H. and Iwamasa, K. (2004). A modeling study of ionospheric conductivities in the high-latitude electrojet regions. Journal of Geophysical Research 109: doi: 10.1029/2003JA010181. issn: 0148-0227.

It is important to accurately determine the ionospheric conductivities for a better estimation of energy deposition in the upper atmosphere, particularly at high latitudes. It is a common practice to assume that enhancements in the conductivities are caused by solar radiation and particle precipitation, which can be regarded as external origins. However, little attention has been paid to effects caused by the presence of electrojet currents themselves. We call this effect an internal origin for influencing the ionospheric conductivities. The presence of electrojet current changes the conductivities, and, in turn, the already changed conductivities modify the current systems. That is, a feedback process is expected to take place in magnetosphere-ionosphere coupling current systems. We use a one-dimensional high-latitude ionospheric model in which the continuity equations, as well as momentum and energy equations, are solved self-consistently to study the conductivities in auroral regions where electrojets exist. The heating effect from the Farley-Buneman instability, which possibly occurs in the electrojet regions, is considered. Electrojet-related joule heating and frictional heating are also taken into account. Thermal processes are analyzed in response to the electrojet current. As a result of changes in the thermal structure, we demonstrate the response of the conductivities due to changes in the chemical reaction rate, which results in a higher electron density. The response of altitude profiles of the conductivities is determined by changes in the collision frequency of ions and electrons with neutral components, while an enhancement in the conductance is mainly caused by the electron density. The results show that both the Hall and Pedersen conductances, i.e., the height-integrated conductivities, increase significantly. The ratio between Hall and Pedersen conductances also changes considerably.

BACKGROUND DATA FILES

Abstract

Keywords
Ionosphere, Plasma temperature and density, Ionosphere, Electric fields, Ionosphere, Ionosphere/magnetosphere interactions, Ionosphere, Ionization mechanisms, Ionosphere, Ionospheric dynamics, conductivity, electrojet, ionosphere
Journal
Journal of Geophysical Research
http://www.agu.org/journals/jb/
Publisher
American Geophysical Union
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