July 19, 2013, 12:00 pm - 1:00 pm

July 19, 2013, 12:00 pm - 1:00 pm, Heliophysics Director's Seminar

The role of field-aligned currents (FACs) in Magnetosphere-Ionosphere coupling

Eftyhia Zesta (673), Mei-Ching Fok (673), and Sonya Lyatsky (673)

The interaction between the magnetized solar wind and the Earth’s magnetosphere results in a convection E-field that is applied across the width of the magnetosphere and down to the polar ionosphere along magnetic field lines generating the so-called Region 1 (R1) field-aligned currents (FACs). FACs flow into and out of the ionosphere in the two polar regions and can be as large as 1-3 MA and transport energy from the magnetosphere into the ionosphere, and upper atmosphere. The electric field applied across the magnetosphere results in convective flow of plasmas in the magnetosphere and near-earth plasma sheet, which result in the formation of a ring current that feeds the so-called Region 2 or R2 FACs. The magnitude of the R2 currents is approximately half that of the R1 currents. R1 and R2 FACs close in the ionosphere via currents flowing within the ionospheric layer. We look at 3 aspects of these large-scale FACs and their magnetospheric circuit: (a) their overall driven response during solar wind dynamic pressure enhancements, (b) the role of the ring current in MI coupling, and (c) inter-hemispheric currents that are generated when the two polar ionospheres are under dramatically different illumination conditions.