Abstract
AbstractPlasma structures with enhanced dynamic pressure, density, or speed are often observed in Earth's magnetosheath. We present a statistical study of these structures, known as jets and fast plasmoids, in the magnetosheath, downstream of both the quasi‐perpendicular and quasi‐parallel bow shocks. Using measurements from the four Magnetospheric Multiscale (MMS) spacecraft and OMNI solar wind data from 2015–2017, we present observations of jets during different upstream conditions and in the wide range of distances from the bow shock. Jets observed downstream of the quasi‐parallel bow shock are seen to propagate deeper and faster into the magnetosheath and on toward the magnetopause. We estimate the shape of the structures by treating the leading edge as a shock surface, and the result is that the jets are elongated in the direction of propagation but also that they expand more quickly in the perpendicular direction as they propagate through the magnetosheath.
Highlights
The bow shock is the boundary at which the speed of the solar wind abruptly drops as it approaches Earth
We present a statistical study of these structures, known as jets and fast plasmoids, in the magnetosheath, downstream of both the quasi‐perpendicular and quasi‐parallel bow shocks
An anticorrelation between density and temperature is a typical signature of magnetosonic waves. These results suggest that jets and fast plasmoids are magnetosonic in nature
Summary
Ions reflected at the quasi‐parallel shock travel as beams through the upstream plasma, generating waves in the foreshock region through wave‐particle interaction (e.g., Wilson et al, 2013) This is where short large‐amplitude magnetic structures (SLAMS) have been observed (Schwartz et al, 1992). Global electromagnetic hybrid simulations (Omidi et al, 2014) suggest that jets that have been formed at the quasi‐parallel bow shock for small IMF cone angles may extend into the quasi‐perpendicular magnetosheath at the flanks. We investigate jets in the quasi‐perpendicular magnetosheath We will compare their evolution and relation to upstream parameters, with previous statistical studies of jets, downstream of the quasi‐parallel bow shock. We compare several models of the jet formation mechanism and provide quantitative predictions of jet propagation toward the magnetopause
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