Solar wind deceleration in the foreshock as the source of the foreshock compressive structures

The foreshock is a turbulent region located upstream of the quasi parallel bow shock. It is dominated by waves and reflected back-streaming particles that interact with each other and result in the creation of different foreshock phenomena. Xirogiannopoulou et al. (2023) found that the deceleration of the solar wind in the foreshock region plays a major role in the creation of subsolar structures with enhanced density or/and magnetic field magnitude, like plasmoids, SLAMS and mixed structures. Moreover, they have found that their formation is increasing with increased velocity of the pristine solar wind. Previous studies, established that foreshock structures are connected with MSH jets (Raptis et al., 2022).  Simultaneously, Koller et al. (2023) researched the connection between the MSH jets and solar wind structures and concluded that the high-speed streams (HSS) create a more favorable environment for the jet creation. Following these results, we use measurements of the Magnetospheric Multiscale Spacecraft (MMS) and OMNI solar wind database between the years 2015 and 2018 and present a statistical analysis considering the presence of solar wind phenomena and their effect in the appearance rate of the compressive foreshock structures. We attempt to explore the origin of these structures and analyze their connection with the notable decrease (10–15 %) of the solar wind speed inside the foreshock region.