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Field aligned currents in the high latitude, high altitude magnetosphere: POLAR initial results
Author(s) -
Russell C. T.,
Zhou X.W.,
Le Guan,
Reiff P. H.,
Luhmann J. G.,
Cattell C. A.,
Kawano H.
Publication year - 1997
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 - 10.1029/97gl01493
Subject(s) - polar , magnetosphere , latitude , northern hemisphere , physics , noon , altitude (triangle) , geophysics , field line , geology , atmospheric sciences , magnetic field , geodesy , astronomy , geometry , mathematics , quantum mechanics
Magnetic field measurements obtained by the POLAR spacecraft are used to map out the region 1 and region 2 field‐aligned current systems in the dayside hemisphere at radial distances of close to 8 Earth radii above the northern polar cap. The extrapolated invariant latitude of these currents is quite variable. The equatorward edge of the region 1 system ranges from 73 to 83° degrees invariant latitude. The sense of both systems reverses across noon as expected. The strength of the currents also varies, averaging about 0.03 A/m for the region 1 currents and 0.01 A/m for the region 2 currents. Over the dayside hemisphere this amounts to about 1.5 million amps flowing down and up the field lines in the region 1 system and about 0.5 million amps in the region 2 system. These numbers and the behavior of the current are quite consistent with low‐altitude observations.