Study of the Local Bow Shock Environment during Magnetosheath Jet Formation: Vlasiator Results

Abstract

Magnetosheath jets are a class of phenomena that are usually defined as structures of enhanced dynamic pressure in the magnetosheath. The origins of some jets have been traced back to steepening ULF waves in the foreshock, but other formation mechanisms have also been described. In this study we use four 2D simulation runs of the global magnetospheric hybrid-Vlasov simulation Vlasiator to investigate the formation of magnetosheath jets at the bow shock. We use 2D views of the simulation and virtual spacecraft to investigate the plasma and magnetic field properties around and at the times and locations of jet formation. We find that of the 796 jets analysed this way, 91% appear to form in association with foreshock structures of enhanced dynamic pressure impacting the bow shock. These jets mainly form downstream of the ULF foreshock, while the remaining 9% are generally found near the ULF foreshock edges toward the flanks and have different properties from the foreshock structure-associated jets.