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Field‐aligned ionospheric current systems observed from Magsat and Oersted satellites during northward IMF
Author(s) -
Stauning P.
Publication year - 2002
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 - 10.1029/2001gl013961
Subject(s) - ionosphere , geophysics , interplanetary magnetic field , latitude , physics , earth's magnetic field , magnetic field , geomagnetic storm , atmospheric sciences , solar wind , astronomy , quantum mechanics
Combination of Magsat and Oersted high‐precision magnetic measurements has provided detailed and consistent patterns of ionospheric field‐aligned current (FAC) patterns during intervals of northward interplanetary magnetic field ( NBZ ) conditions. Our analysis has revealed that the NBZ FAC currents extend from two rounded or bean‐shaped ionospheric regions centered at 85° geomagnetic latitude and magnetic local times of approximately 0900 for the upward and 1500 for the downward FAC. The locations of the NBZ FAC regions are almost invariant to seasonal variations and to variations in the magnitude of IMF B z . The NBZ FAC currents are sizeable for summer conditions only and vanishes during equinox and winter seasons. The NBZ FAC intensity is a strongly non‐linear function of IMF B z with a marked threshold at around +5 nT. The observed characteristics indicate that the NBZ currents are the competing high‐latitude counterpart of the region 1 ( R1 ) low‐latitude boundary layer currents.