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Ionospheric conductances and currents of a morning sector auroral arc from Swarm‐A electric and magnetic field measurements
Author(s) -
Juusola L.,
Archer W. E.,
Kauristie K.,
Burchill J. K.,
Vanhamäki H.,
Aikio A. T.
Publication year - 2016
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2016gl070248
Subject(s) - electrojet , electric field , ionosphere , geophysics , arc (geometry) , swarm behaviour , magnetic field , electric current , equatorial electrojet , physics , electric potential , field (mathematics) , magnetometer , geodesy , geology , earth's magnetic field , voltage , geometry , mathematics , mathematical optimization , quantum mechanics , pure mathematics
We show the first ionospheric Hall and Pedersen conductances derived from Swarm magnetic and electric field measurements during a crossing of a morning sector auroral arc. Only Swarm‐A was used, with assumptions of negligible azimuthal gradients and vanishing eastward electric field. We find upward field‐aligned current, enhanced Hall and Pedersen conductances, and relatively weak electric field coincident with the arc. Poleward of the arc, the field‐aligned current was downward, conductances lower, and the electric field enhanced. The arc was embedded in a westward electrojet, immediately equatorward of the peak current density. The equatorward portion of the electrojet could thus be considered conductance dominant and the poleward portion electric field dominant. Although the electric field measured by Swarm was intense, resulting in conductances lower than those typically reported, comparable electric fields have been observed earlier. These results demonstrate how Swarm data can significantly contribute to our understanding of the ionospheric electrodynamics.