The Earth's dipole tilt angle changes both diurnally and seasonally and introduces numerous variabilities in the coupled magnetosphere‐ionosphere system. By altering the location and intensity of magnetic reconnection, the dipole tilt influences convection on a global scale. However, due to the nonlinear nature of the system, various other effects like dipole rotation, varying interplanetary magnetic field (IMF) orientation, and nonuniform ionospheric conductance can smear tilt effects arising purely from changes in coupling with the solar wind. To elucidate the underlying tilt angle dependence, we perform magnetohydrodynamic (MHD) simulations of the steady‐state magnetosphere‐ionosphere system under purely southward IMF conditions for tilt angles from 0–90°. We identify the location of the magnetic separator in each case and find that an increasing tilt angle shifts the 3‐D X line southward on the magnetopause due to changes in magnetic shear angle. The separator is highly unsteady above 50° tilt angle, characteristic of regular flux transfer event (FTE) generation on the magnetopause. The reconnection rate drops as the tilt angle becomes large, but remains continuous across the dayside such that the magnetosphere is open even for 90°. These trends map down to the ionosphere, with the polar cap contracting as the tilt angle increases, and region I field‐aligned current (FAC) migrating to higher latitudes with changing morphology. The tilt introduces a north‐south asymmetry in magnetospheric convection, thus driving more FAC in the Northern (sunward facing) hemisphere for large tilt angles than in the Southern independent of conductance. These results highlight the strong sensitivity to onset time in the potential impact of a severe space weather event.

The Earth's magnetopause exists in a delicate balance between forces exerted between the impinging solar wind and the Earth's intrinsic magnetic field. The subsolar magnetopause is typically located approximately ten Earth radii (R E ) upstream but, during periods of enhanced solar wind forcing, this can be compressed to half this distance and inside the drift paths of radiation belt electrons and protons (Shprits et al., 2006) and the orbits of geosynchronous satellites (Cahill & Winckler, 1999). Moreover, magnetopause motion can drive global ultra-low-frequency (ULF) pulsations (Green & Kivelson, 2004;Li et al., 1997) and intense ionospheric and ground induced current systems (Fujita et al., 2003;Smith et al., 2019). The dynamics and location of the magnetopause are therefore of wide relevance to the understanding of planetary magnetospheres and to space weather forecasting.The location and shape of the magnetopause was initially theoretically predicted to depend on the pressure exerted by a stream of charged particles from the Sun (Chapman & Ferraro, 1931) and its three dimensional geometry was derived based on solar wind dynamic pressure alone (Mead & Beard, 1964). Measurements

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The solar wind impinging on the dayside magnetosphere compresses the magnetospheric field lines and enhances the equatorial magnetic field magnitude (Mead & Beard, 1964;Northrop, 1966; Roederer, 1970). Close to the magnetopause, the equatorial field strength can consequently exceed the field strength at a given particle's mirror point which causes drift orbits in the outer magnetosphere to bifurcate as particles become temporarily trapped within high-latitude pockets of magnetic field minima. Entering and exiting these non-dipolar regions has been associated with non-conservation of the particles second adiabatic invariant (Antonova et al., 2003) which, combined with conservation of the first adiabatic invariant, leads to radial transport across the magnetic field. It is therefore necessary to account for this phenomenon to understand and predict the dynamics of the outer radiation belt and its source populations.The early works of Shabansky and Antonova (1968) and Shabansky (1972) identified the phenomenon of drift orbit bifurcations (DOBs) and described how this can affect particles on both open and closed field lines. Early observations of enhanced energetic proton and electron fluxes in the high-latitude part of the trapping region were identified by several early satellite missions (