Magnetospheric signatures of ionospheric density cavities observed by Cluster
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We present Cluster measurements of large amplitude electric fields corre- lated with intense downward field-aligned currents, observed during a nightside crossing of the auroral zone. The data are reproduced by a simple model of magnetosphere-ionosphere coupling which, under different conditions, can also produce a divergent electric field signature in the downward current region, or correlation between the electric and perturbed magnetic fields. We conclude that strong electric field associated with intense downward field-aligned current, such as this observation, is a signature of ionospheric plasma depletion caused by the downward current. It is also shown that the electric field in the downward current region correlates with downward current density if a background field is present, e.g. due to magnetospheric convection.
Russell , A J B , Karlsson , T & Wright , A N 2015 , ' Magnetospheric signatures of ionospheric density cavities observed by Cluster ' Journal of Geophysical Research: Space Physics , vol 120 , no. 3 , pp. 1876-1887 . DOI: 10.1002/2014JA020937
Journal of Geophysical Research: Space Physics
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