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SUMMARY:The role of Birkeland currents in the Dungey cycle - John Coxon\, 
 University of Southampton
DTSTART:20180209T110000Z
DTEND:20180209T120000Z
UID:TALK98362@talks.cam.ac.uk
CONTACT:Dr Robert Shore
DESCRIPTION:John Coxon from the University of Southampton is visiting the 
 British Antarctic Survey on February 9th – join us for an exciting semin
 ar on space physics and electrodynamic interactions in near-Earth space.  
 All are welcome!\n\nAbstract:\n\nBirkeland currents\, also known as field-
 aligned currents\, are currents which flow along Earth’s magnetic field 
 lines\, electrodynamically linking the magnetopause and partial ring curre
 nt to the ionosphere. I use six years of observations from the Active Magn
 etosphere and Planetary Electrodynamics Response Experiment (AMPERE) to in
 vestigate how Birkeland currents react to magnetic reconnection in the con
 text of the Dungey cycle. I begin by establishing a correlation between ma
 gnetic reconnection and the amount of Birkeland current flowing\, and then
  compare the Milan model to AMPERE data\, showing that the current flow ca
 n be considered as a function of reconnection and conductivity (via solar 
 zenith angle). As part of this\, I detail an apparent disparity between th
 e Northern and Southern Hemisphere\, which may indicate a fundamental asym
 metry between the two. Then\, I specifically consider the reaction of Birk
 eland currents to nightside reconnection during substorms by performing tw
 o superposed epoch analyses to examine the current flowing in the system a
 nd the size of the current ovals on either side of substorm expansion phas
 e onset\, addressing open questions on the nature of the substorm current 
 wedge.
LOCATION:British Antarctic Survey\, Innovation Centre\, Seminar Room 1
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