On the interaction of interplanetary shocks and solar wind turbulence

The propagation of collisionless shocks through the turbulent magnetized plasmas has been investigated for decades. The processes connected with the formation and propagation of Interplanetary (IP) shocks play a key role in the acceleration of particles and in the coupling to the Earth’s magnetosphere. However, many aspects of the interactions are poorly understood, e.g., the regime of turbulence in downstream/upstream medium, heating of the downstream plasma via turbulent dissipation, etc. Recently, a few authors have addressed the nature of fluctuations within the downstream regions of IP shocks and sheaths of ICMEs. In general, they have found that an IP shock enhances the fluctuation energy within the downstream plasma. Consequently, this should lead to the enhanced heating of the shocked plasma. In this study, we investigate whether the downstream region exhibits such a heating. In the analysis, we stress that the downstream region (in situ observation by a spacecraft) of an IP shock is an evolutionary record of the shocked plasma, i.e., the leading edge of a sheath is plasma that has been just shocked, while the plasma recorded 1 hour after the shock passage has been shocked roughly 5–6 hours earlier, on average. We illustrate this point investigating the relation of the enhanced levels of turbulent fluctuations by the IP shocks and the temperature evolution in the downstream plasma. Preliminary results suggest that the level of enhanced fluctuations affects the temperature profile in this region.