Simulated ring current response during periods of dawn‐dusk oriented interplanetary magnetic field (B_y)

Abstract

[1] Ring current formation is mainly attributed to enhanced global magnetospheric convection and particle injection. One of the indicators of enhanced global magnetospheric convection is the transpolar potential. The transpolar potential has been shown to respond to dawn-dusk oriented interplanetary magnetic field (IMF), enhancing as the IMF magnitude grows. This suggests that the ring current should respond to dawn-dusk oriented IMF. This work examines the ring current response during periods of dawn-dusk oriented IMF using the Lyon-Fedder-Mobarry and Comprehensive Ring Current Model simulations. Exploring three hypotheses, this work shows through simulation results that the ring current does respond during periods of dawn-dusk oriented IMF, that the inner magnetospheric response is different for periods of dawn-dusk oriented IMF than for periods of southward IMF, and that these differences are attributed to both lower magnetospheric convection on closed field lines and the location of the reconnection region on the nightside. Specifically, the simulation results show that as the magnitude of the dawn-dusk oriented IMF increases, producing a corresponding increase in the transpolar potential, the ring current response increases. The response is always much less than a comparable southward IMF would produce. This lower response is due to both magnetospheric convection on closed field lines, which builds the ring current but at a slower rate, and flank reconnection, which allows energy to flow through the inner magnetosphere without building the ring current plasma population (as a conduit).

MHD simulations using average solar wind conditions for substorms observed under northward IMF conditions

“…The arc formation and motion is affected by IMF B y as well. In addition, Mitchell et al [2013] showed that ring current, which is attributed to enhancing global magnetospheric convection, increases with increasing IMF B y magnitude.…”

Effects of IMF By on Ring Current Asymmetry Under Southward IMF Bz Conditions Observed at Ground Magnetic Stations: Case Studies

“…Although there exists many studies that show the importance of IMF Bz (e.g., Liemohn et al, 1999; Liemohn, Kozyra, Thomsen, et al, 2001) and the solar wind dynamic pressure (e.g., Shi et al, 2006) on the asymmetry of the ring current, the role of IMF By on ring current asymmetry has not been explored enough. There are very few studies on the effects of IMF By on ring current (e.g., Mitchell et al, 2013). Mitchell et al (2013) using simulation study suggested that the IMF By plays an important role in the ring current intensity as positive IMF By can increase the transpolar potential.…”

“…There are very few studies on the effects of IMF By on ring current (e.g., Mitchell et al, 2013). Mitchell et al (2013) using simulation study suggested that the IMF By plays an important role in the ring current intensity as positive IMF By can increase the transpolar potential. However, they did not investigate the IMF By effects on ring current asymmetry.…”