Investigation of the Interaction Between Magnetosheath Reconnection and Magnetopause Reconnection Driven by Oblique Interplanetary Tangential Discontinuity Using Three‐Dimensional Global Hybrid Simulation

Abstract

Magnetosheath reconnection due to the interaction of an interplanetary directional discontinuity with the bow shock and Earth's magnetosphere under an initially northward interplanetary magnetic field (IMF) has been investigated in previous simulations (e.g., Guo et al., 2018, https://doi.org/10.1029/2018ja025679). Under an initially southward IMF, the magnetosheath reconnection could interact with reconnection at the magnetopause. In this study, using three‐dimensional (3D) global‐scale hybrid simulations, we present cases with incoming tangential discontinuities (TDs) in an initially southward IMF, which possess various magnetic field rotation angles (ΔΦ) and half‐width (w), to study the effects of pre‐existing magnetopause reconnection on the formation of magnetosheath flux ropes, as well as the subsequent interaction between the magnetopause reconnection and magnetosheath reconnection, with downstreams of both Quasi‐perpendicular (Q‐⊥) and Quasi‐parallel (Q‐||) shock examined. The initial IMF is assumed to be oblique, with a finite Bx and Bz, similar to that in Guo et al. (2018), https://doi.org/10.1029/2018ja025679 but with a southward Bz < 0. Compared with the cases with an initially northward IMF, magnetopause reconnection weakens the compression processes of the TD and leads to less frequent reconnection in the magnetosheath. The existence and the structure of magnetosheath reconnection are found to strongly depend on the parameters w and ΔΦ of the TD. When interacting with the magnetopause reconnection, the magnetosheath flux ropes can re‐reconnect with the geomagnetic dipole field lines, forming new structures of magnetopause flux ropes. The resulting evolution of flux rope configuration is illustrated.

Global Hybrid Simulations of Interaction Between Interplanetary Rotational Discontinuity and Bow Shock/Magnetosphere: Can Ion‐Scale Magnetic Reconnection be Driven by Rotational Discontinuity Downstream of Quasi‐Parallel Shock?

“…The RD is compressed by the initially Q‐⊥ bow shock and then the magnetosheath, similar to that in the TD/bow shock interaction as reported by Pang et al. (2010), Guo, Lin, Wang, and Du (2018), and Guo, Lin, and Wang (2021). The transmitted RD is the thinnest around z = 7.0 R E , where it was first in contract with the bow shock.…”

“…Figure 7 exhibits the zoomed‐in contour plots of (Figure 7a) the component j y of current density (Figure 7b), the component B y (Figure 7c), the electric fields and (Figure 7d) (Figure 7e), the ion bulk flow component V iz (Figure 7f), (Figure 7g), J ⋅ E′ (Figure 7h), the ion density N i , and (Figure 7i) the ion temperatures T ∥ and (Figure 7j) T ⊥ , from x = 0 to 12.0 R E and z = 4.0 R E to 16.0 R E , where black lines superposed on the contours are the field lines projected onto the 2D noon meridian plane. By shock compression and convection compression processes at the bow shock and in the magnetosheath (Guo, Lin, & Wang, 2021; Guo, Lin, Wang, & Du, 2018; Pang et al., 2010), a thin current sheet with width of ∼3.0 d i 0 is formed above the equator in the magnetosheath, as shown in Figure 7a. The evolution of the current density inside the RD will be elaborated in Figure 8.…”

“…as suggested by simulations (Cable & Lin, 1998;Lin, Swift, et al, 1996;Tsubouchi & Matsumoto, 2005) and observations (Archer et al, 2012;Karlsson et al, 2018). Magnetic reconnection has been observed in the magnetosheath due to the interaction of an interplanetary TD with the bow shock (e.g., Guo, Lin, & Wang, 2021;Guo, Lin, Wang, & Du, 2018;Lin, 1997;Maynard, Burke, et al, 2007;Maynard, Sonnerup, et al, 2002;Omidi et al, 2009;Pang et al, 2010;Phan, Love, et al, 2011;Phan, Paschmann, et al, 2007). Phan, Paschmann, et al (2007) and Phan, Love, et al (2011) have suggested, with both Cluster and THEMIS observations, that reconnection is present in the magnetosheath as a result of the compression of the solar wind current sheet.…”

“…Magnetic reconnection has been observed in the magnetosheath due to the interaction of an interplanetary TD with the bow shock (e.g., Guo, Lin, & Wang, 2021; Guo, Lin, Wang, & Du, 2018; Lin, 1997; Maynard, Burke, et al., 2007; Maynard, Sonnerup, et al., 2002; Omidi et al., 2009; Pang et al., 2010; Phan, Love, et al., 2011; Phan, Paschmann, et al., 2007). Phan, Paschmann, et al.…”

“…2D (Omidi et al., 2009) and three‐dimensional (3D) (Pang et al., 2010) global hybrid simulations have shown the generation of magnetosheath reconnection downstream of the quasi‐perpendicular (Q‐⊥) shock due to the TD/bow shock interaction. In addition, using a 3D global hybrid simulation, Guo, Lin, Wang, and Du (2018) and Guo, Lin, and Wang (2021) have investigated the interaction of interplanetary directional TDs with the bow shock and the magnetosphere, which results in magnetic reconnection downstream of both Q‐⊥ and quasi‐parallel (Q‐∥) shocks, and the subsequent impacts on the magnetopause flux ropes.…”