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|Title:||Principal component analysis of Birkeland currents determined by the Active Magnetosphere and Planetary Electrodynamics Response Experiment|
|Authors:||Milan, Stephen Eric|
Carter, J. A.
Anderson, B. J.
|Publisher:||American Geophysical Union (AGU)|
|Citation:||Journal of Geophysical Research: Space Physics, 2015, 120|
|Abstract:||Principal component analysis is performed on Birkeland or field-aligned current (FAC) measurements from the Active Magnetosphere and Planetary Electrodynamics Response Experiment. Principal component analysis (PCA) identifies the patterns in the FACs that respond coherently to different aspects of geomagnetic activity. The regions 1 and 2 current system is shown to be the most reproducible feature of the currents, followed by cusp currents associated with magnetic tension forces on newly reconnected field lines. The cusp currents are strongly modulated by season, indicating that their strength is regulated by the ionospheric conductance at the foot of the field lines. PCA does not identify a pattern that is clearly characteristic of a substorm current wedge. Rather, a superposed epoch analysis of the currents associated with substorms demonstrates that there is not a single mode of response, but a complicated and subtle mixture of different patterns.|
|Rights:||Copyright © 2015, The Authors. This is an open access article under the terms of the Creative Commons Attribution License ( http://creativecommons.org/licenses/by/3.0/ ), which permits use, distribution and reproduction in any medium, provided the original work is properly cited.|
|Appears in Collections:||Published Articles, Dept. of Physics and Astronomy|
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