Statistical Analysis of foreshock plasmoids and SLAMS

The turbulent foreshock region upstream of the quasi-parallel Bow Shock (BS) is dominated by waves and reflected particles that interact with each other and create a large number of different foreshock structures. These structures are carried by the solar wind flow, interact with the bow shock and penetrate downstream to the magnetosheath. The local structures of enhanced density and/or magnetic field, called plasmoids and Short Large Amplitude Magnetic Structures (SLAMS) respectively, as defined by Karlsson et al. (2015) are thought to be the source of transient dynamic pressure enhancements in the magnetosheath, the magnetosheath jets. Using measurements from the Magnetospheric Multiscale Spacecraft (MMS) and high-resolution OMNI data, we present a statistical analysis of foreshock compressive structures with increased density and magnetic field. The occurrence of both phenomena is affected by the solar wind modification inside the foreshock in a different way. Plasmoids are observed in highly magnetised and denser regions, whereas SLAMS are common in denser regions with a lower magnetic field.