Magnetosheath Reconnection Before Magnetopause Reconnection Driven by Interplanetary Tangential Discontinuity: A Three‐Dimensional Global Hybrid Simulation With Oblique Interplanetary Magnetic Field

Abstract

Terrestrial dayside dynamics associated with a southward turning, oblique interplanetary magnetic field (IMF) carried by an interplanetary tangential discontinuity (TD) is investigated by performing a three-dimensional global-scale hybrid simulation systematically for cases in which the incoming solar wind TD possesses various magnetic field rotation angles ΔΦ = 90°to 180°and half widths w = 2d i0 to w = 30d i0 , where d i0 is the ion inertial length in the solar wind. Overall, the TD is compressed while being transmitted into the magnetosheath, with different compression processes downstream of the quasi-parallel (Q-||) and quasi-perpendicular (Q-⊥) shocks. It is found that magnetosheath reconnection may take place downstream of both the Q-|| and Q-⊥ shocks due to interaction of the directional TD with the bow shock and magnetopause, but the existence of magnetosheath reconnection depends on w and ΔΦ. Magnetosheath flux ropes are formed through three-dimensional patchy reconnection in the thinned current sheet, with a longer rope lengths under a larger ΔΦ. There exists a dawn-dusk asymmetry in the spatial extent of the flux ropes, which becomes more significant as ΔΦ decreases. When ΔΦ decreases to 90°, no reconnection flux ropes are found. Magnetopause reconnection is initiated when the magnetic fluxes with a southward turning IMF (on the sunward side) reach the magnetopause, and the magnetopause flux ropes can be mixed with the magnetosheath ones. Our simulation demonstrates that the effects of a southward turning of the IMF may not be a simple field direction change that leads to reconnection only at the magnetopause.This manuscript is organized as follows. The simulation model is described in section 2. The simulation results are presented in section 3, and the summary and discussion are given in section 4. Simulation ModelNumerical simulation based on a 3-D global-scale dayside hybrid code (Lin & Wang, 2005) is performed in this study. The geocentric solar-magnetospheric (GSM) coordinate is used, in which the x axis points from the

Turbulence‐Driven Magnetic Reconnection in the Magnetosheath Downstream of a Quasi‐Parallel Shock: A Three‐Dimensional Global Hybrid Simulation

“…The X1 line is located at (x, z) = (5.2, 8.7)R E in the meridian plane. and are then compressed (Lin, 1997;Phan et al, 2007;Omidi et al, 2009;Guo et al, 2018). However, it is also different from that in our simulation, where magnetic reconnection occurs in the downstream current sheets formed after the excited large-amplitude low-frequency electromagnetic waves cross the shock.…”

“…However, in our simulation, the current sheets are formed due to the compression of large‐amplitude low‐frequency electromagnetic waves in the quasi‐parallel shocked magnetosheath behind the bow shock. Magnetic reconnection can also be induced in the downstream of the bow shock when the current sheets in the solar wind cross the shock and are then compressed (Lin, ; Phan et al, ; Omidi et al, ; Guo et al, ). However, it is also different from that in our simulation, where magnetic reconnection occurs in the downstream current sheets formed after the excited large‐amplitude low‐frequency electromagnetic waves cross the shock.…”

Magnetopause Reconnection as Influenced by the Dipole Tilt Under Southward IMF Conditions: Hybrid Simulation and MMS Observation

“…In this study, we use a 3‐D dayside global‐scale hybrid simulation model (Guo et al, 2018; Y. Lin & Wang, 2005; Tan et al, 2011) to investigate the GEM Dayside Kinetic Challenge magnetopause reconnection event observed by MMS under southward IMF. The parameters chosen in the simulation run are listed at the Community Coordinated Modeling Center (CCMC, https://ccmc.gsfc.nasa.gov/support/GEM/Dayside_Kinetic_Processes/Dayside_Kinetic_Challenge/Introduction.php).…”

Analytical study of gyrophase, pitch angle, and normal speed of particles leaving an ideal magnetohydrodynamic discontinuity surface

“…To help address these questions we obtain the particle's speed and displacement as a function of time in the direction normal to the surface from the dot product of (1) and (2), respectively, withn (cf. equations (18) and (19) in [39]…”

“…The large-scale properties of boundaries observed in space plasmas, such as the Earth's magnetopause or bow shock, are consistent with those of one or other of the above MHD discontinuities (e.g., [37]) and a wide variety of plasma phenomena observed in space are therefore described and modelled within the theoretical framework of MHD. Such is the case, to name but a few, of tangential and rotational discontinuity-driven foreshock bubbles [26], the propagation of waves along contact discontinuities in the solar atmosphere [38], the interaction of a magnetosheath jet with a magnetopause modelled as a tangential discontinuity [43], or the effect of interplanetary tangential discontinuities on the magnetosheath and the magnetopause [19].…”