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Magnetospheric signatures of ionospheric density cavities observed by Cluster
Author(s) -
Russell A. J. B.,
Karlsson T.,
Wright A. N.
Publication year - 2015
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1002/2014ja020937
Subject(s) - electric field , ionosphere , physics , geophysics , magnetosphere , current (fluid) , amplitude , computational physics , field (mathematics) , current density , electric current , cluster (spacecraft) , magnetic field , optics , mathematics , quantum mechanics , pure mathematics , thermodynamics , computer science , programming language
We present Cluster measurements of large amplitude electric fields correlated 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.