Scale Size Estimation of Magnetosheath Jets

Transient enhancements in the dynamic pressure, so-called magnetosheath jets or simply jets, are abundant in the magnetosheath.They propagate from the bow shock towards the magnetopause. On their way through the magnetosheath, jets interact with theambient plasma. The scale size of jets is determined almost exclusively with statistical studies, but not for individual jet events.We use multipoint measurements from the Time History of Events and Macroscale Interactions during Substorms (THEMIS) missionto study the passage of a single jet and obtain its size. We observe an evasive motion of the plasma on the jet path. Using thisflow pattern we can reconstruct the position of the central axis of this jet along its propagation direction. This allows us toestimate the spatial distribution of the dynamic pressure within the jet. Furthermore, the size perpendicular to thepropagation direction can be estimated for different cross sections. Using this method, the scale size of individual jet eventscan be determined with multiple spacecraft. In principle, only two spacecraft are needed if we assume a simplified geometry.In the case we investigated, both the dynamic pressure and the perpendicular size increase along the propagation axis fromthe front part towards the center of the jet and decrease again towards the rear part.