Magnetosheath Jets Associated With a Solar Wind Rotational Discontinuity in a Hybrid-Vlasov Simulation

Abstract

Magnetosheath jets are transient enhancements of dynamic pressure downstream of collisionless shocks. In Earth's magnetosheath they are mostly found downstream of the quasi-parallel bow shock during steady solar wind and low interplanetary magnetic field (IMF) cone angle conditions, but they have also been observed in the quasi-perpendicular magnetosheath and during different solar wind conditions. In this study we use a 2D simulation run of the global hybrid-Vlasov model Vlasiator to investigate how the interaction between the bow shock and a solar wind rotational discontinuity influences the formation of magnetosheath jets. Separating the jets identified in the simulation based on formation site and time relative to the interaction between the discontinuity and the shock, we conduct a statistical study to find the characteristic properties of the different jet types. We find that jets forming at the quasi-parallel shock are similar to each other regardless of the stage of the shock-discontinuity interaction. Jets forming at the quasi-perpendicular shock after the discontinuity has passed are small and short-lived. The jets forming at the quasi-perpendicular shock as the discontinuity impacts it, on the other hand, merge with each other into a large and long-lived transient density enhancement that propagates deep into the magnetosheath together with the discontinuity, giving it the potential to be more geoeffective than the other types. This study sheds light on the properties of jets and jet-like structures that form during non-steady solar wind and IMF conditions, and the results can be of use when classifying similar events from spacecraft observations.