Magnetic reconnection at multi-scales from the terrestrial bow shock to the magnetopause

The quasi-parallel bow shock creates highly turbulent conditions favourable for magnetic reconnection in the shock region, its downstream magnetosheath, and at the magnetopause. Upstream of the bow shock, the presence of reflected particles excites ultra-low frequency waves, which interact nonlinearly as they are convected towards the bow shock, creating plasma structures which can affect the magnetosheath and magnetopause. At the bow shock, MMS observations have shown that both regular and electron-scale reconnection occur, while other observations show that high-speed jets – regions of enhanced dynamic pressure in the magnetosheath – can trigger reconnection at the magnetopause. We discuss 3D global hybrid and local fully kinetic simulations at and downstream of the quasi-parallel shock. In the hybrid simulations, we show how the effects of foreshock turbulence and the impact of high-speed jets on the magnetopause can lead to magnetopause reconnection events in addition to the quasi-steady reconnection that takes place due to southward magnetic fields, and discuss how this compares to observations. In the 3D kinetic simulations, we study the evolution of current sheets in the shock transition region, showing different configurations not captured by 2D simulations. The electron-scale reconnection is fast and transient, and we perform comparisons to MMS observations.