Abstract
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.