Alfvén resonance on Kelvin-Helmholtz vortices at the Earth’s magnetopause

The Alfvén resonance is an extensively observed phenomenon in astrophysics, playing a crucial role in understanding energy transfer, macroscopic structure, and evolutionary processes within celestial environments such as the magnetospheres of stars, planets, and other astrophysical objects. In this work, we investigate the spatial and temporal distribution of the Alfvén resonance points during the evolution of Kelvin-Helmholtz instability (KHI) at Earth’s dusk-flank magnetopause in numerical MHD simulation. The results show that, there is no appearance of the Alfvén resonance points $P_{AR}$ $P_{AR}$ during the linear phase. In the early nonlinear phase, the Alfvén resonance points $P_{AR}$ $P_{AR}$ , whose duration time is approximately $\mathrm{\Delta }{t}_1\sim 3t_A$ $\Delta {t_{1}} \sim 3{t_{A}}$ , looks like the “eyelid” of the KH vortex. During the nonlinear growth phase, the Alfvén resonance points $P_{AR}$ $P_{AR}$ , whose duration time is about $\mathrm{\Delta }{t}_2\sim 6t_A$ $\Delta {t_{2}} \sim 6{t_{A}}$ , appear at both the “eyelid” and the outer “corner” of the KH vortex. The Alfvén resonance phenomenon disappears with the decay of KH vortex.