The turbulent foreshock region upstream of the quasi-parallel bow shock is dominated by waves and reflected particles that interact with each other and create a large number of different foreshock transients. The structures with the enhanced magnetic field (Short Large Amplitude Magnetic Structures, SLAMS) and density spikes named plasmoids are frequently observed. They are one of the suggested sources of transient flux enhancements (TFE) or jets in the magnetosheath. Using measurements of the Magnetospheric Multiscale Spacecraft (MMS) and OMNI solar wind database between the 2015 and 2018 years, we have found that there is a category of events exhibiting both magnetic field and density enhancements simultaneously and we introduce the term “mixed structures” for them. Consequently, we divided our set of observations into three groups of events and present their comparative statistical analysis in the subsolar foreshock. Based on our results and previous research, we discuss the properties, possible origin and occurrence rates these events under different upstream conditions and their possible relation to the jet and plasmoid formation in the magnetosheath.

The Martian ionosphere, modulated by the solar wind from the topside and remnant crustal magnetic fields close to the surface, possesses unique structures different from Earth and Venus. Integrated observations by the plasma and magnetic field instruments onboard the Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft show evidence of ionospheric plasma depletions, independent of seasonal variations at Mars. During such depletions, the density of all ionospheric ion species is reduced by more than an order of magnitude, and, at the same time, the electron temperature increases abruptly. An automated algorithm for the identification of such plasma depletions is developed. Altogether, as many as 1177 events are identified in 8618 orbits available from October 2014 to May 2021. A statistical investigation of these events reveals that they are more prominent on the nightside. Their higher occurrence in the southern hemisphere suggests a possible relation to the crustal magnetic fields. While the dayside events occur mainly at altitudes above about 200 km, nightside event altitudes are typically lower. Considering the relation between spacecraft velocity and observed event duration, we suggest that the depletions are bubble-like structures, more elongated horizontally than vertically. A possible mechanism of their formation is discussed.

A broad statistical study addresses for the first time an evolution of ultra-low frequency (ULF) waves/fluctuations in the terrestrial foreshock around the Moon generated through the interaction between the back-streaming particles reflected from the bow shock and the incoming solar wind. They propagate sunward but are convected by the solar wind flow back toward the bow shock and their amplitudes grow. However, our study shows that waves could be growing as well as decaying towards the bow shock under the quasi-radial interplanetary magnetic field. We demonstrate that the statistically determined growth rate is positive and larger for compressive variations of the density and magnetic field strength than for its components. We show that even if a possible influence of the Moon and its wake is excluded, the growth rate is decreased by non-linear effects leading to saturation of the wave amplitude.