The Effects of Magnetospheric Convection on Atmospheric Electric Fields in the Polar Cap
It is well-known that a potential difference of some 30 to 300 kV exists between the dawnside and the duskside boundaries of the polar cap ionosphere. This potential difference arises from interactions between the solar wind and the magnetosphere. In this paper we examine how the resulting ionospheric electric fields map down to the lower atmosphere. It is found that such fields map down to balloon altitudes of 30–40 km with little attenuation or distortion, in agreement with several previous authors’ results. It is also found that the mapping efficiency is not significantly affected by conductivity changes during auroral and polar cap absorption events, provided that these changes occur over areas larger than the scale size of electric fields involved. These results generally support the ideas behind balloon measurements of ionospheric electric fields. It also appears possible to infer magnetospheric convection electric fields from simultaneous ground-based measurements of vertical atmospheric fields at suitably spaced stations in the polar cap.
KeywordsSolar Wind Mapping Factor Atmospheric Electric Field Conductivity Profile Magnetospheric Convection
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