Persistence and Dynamics of an Sq‐like Mid‐Latitude Current Vortex During the May 2024 Superstorm

Abstract The solar quiet (Sq) current system describes the mid‐latitude equivalent current under quiet geomagnetic conditions, but whether an Sq‐like vortex persists during intense storms remains unclear. Using dense East Asian magnetometer observations, including the Chinese Meridian Project, we reconstruct the storm‐time ionospheric equivalent‐current system during the May 2024 superstorm. Observations reveal a persistent Sq‐like mid‐latitude vortex with enhanced intensity and rapid focus displacement. Its evolution follows the interplanetary magnetic field (IMF) Bz and couples closely with auroral and equatorial currents. Southward IMF Bz enhances magnetospheric convection, driving auroral‐oval expansion and equatorial electrojet intensification that compress the vortex equatorward, whereas northward turnings lead to auroral retreat and counter‐electrojet pulses, which in turn drive the poleward rebound of the mid‐latitude vortex. Our results extend the Tsuji's model by resolving the mid‐latitude vortex, thereby completing the ionospheric current response chain from auroral currents to the Cowling‐enhanced equatorial response.