Transient, Localized Flux Transport Revealed by Electron Microsignatures Downstream of Saturnian Moons

Abstract In Saturn's magnetosphere, the inward transport of magnetic flux is largely carried by localized injection flux tubes filled with warm, tenuous plasma, although their inflow speeds and spatio‐temporal properties remain poorly constrained. Here, we propose that these flux tubes can modify electron microsignatures, the small‐scale, absorption‐induced flux depletions downstream of Saturn's moons, by twisting them into zigzag‐shaped structures in the energy‐time spectrograms of energetic electrons. Using observations from the Cassini spacecraft, we identify zigzag‐shaped microsignatures and reproduce their morphology through test‐particle simulations based on this scenario. The inferred radial velocities at low ‐shells () are on the order of 1 km/s, suggesting significant braking of injection flux tubes and consistent with the observed decline in their occurrence inside . The ability to resolve such low inflow velocities remotely from microsignature distortions offers a new diagnostic for constraining mass and flux circulation in the magnetospheres of giant planets.