[P-EM10] Dynamics of Magnetosphere and Ionosphere

[PEM10-02] An Analysis of Region 2 Field-Aligned Current Bifurcations

★Invited Papers

*Harneet Kaur Sangha^1,2, S E Milan^1,3, B J Anderson⁴, H Korth⁴ (1.Univ. of Leicester, UK, 2.Univ. of Alabama in Huntsville, US, 3.Birkeland Centre for Space Science, Univ. of Bergen, Norway, 4.Johns Hopkins Univ. Applied Physics Laboratory, US)

The Earth’s Field-Aligned Currents (FACs) electrodynamically connect the magnetosphere and the ionosphere, enabling energy and momentum to be transported between the different regions of the solar wind-magnetosphere-ionosphere-thermosphere coupled system. The FACs form two concentric rings in the ionosphere. The higher latitude currents are known as the Region 1 or R1 FACs, and the lower latitude currents are known as the Region 2 or R2 FACs. The R1 currents directly link the ionosphere to the magnetopause at the outer magnetosphere, and the R2 currents link the ionosphere to the ring current in the inner magnetosphere.
Utilizing the Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE), we study the FACs and how they vary with time. Using this dataset, we identified a new phenomenon within the R2 FAC system, coined Region 2 Bifurcations (R2Bs) (Sangha et al., 2020). These R2Bs appear as a second ring of R2-like current, further equatorward than the original R2 FACs. The occurrence of R2Bs shows a peak at substorms, and we also suggest a relationship with Sub-Auroral Polarization Streams (SAPS). To study these connections, we conducted some superposed epoch analyses of some solar wind and geomagnetic conditions, which show both R2Bs and SAPS to be substorm-related processes.