Parker Solar Probe Observations of Turbulence and Waves between a Current Sheet and an Interplanetary Coronal Mass Ejection–Driven Shock

Abstract We report on unusual magnetic wave activity seen in a region between the crossing of a current sheet and an interplanetary shock by the Parker Solar Probe (PSP). The PSP observed a shock driven by an interplanetary coronal mass ejection on 2021 June 30 at 14:58:19 at 0.76 au. Prior to the arrival of the shock, PSP encountered a current sheet on 2021 June 30 at 14:54:54. Through an analysis of the magnetic field and plasma measurements, we determine that the shock is a fast forward quasi-parallel shock. The magnetic field in the region between the current sheet and the shock was characterized by enhanced magnetic wave activity. To investigate the plasma waves in the region, a wavelet technique is applied to obtain the magnetic field fluctuation power spectral density, normalized reduced helicity, and magnetic field fluctuation hodogram. The results of the analysis reveal that the waves present in this region demonstrate right-hand polarization and have a relatively broad range of frequencies in the spacecraft frame. Our analyses reveal the simultaneous presence of low-frequency magnetohydrodynamic waves and whistler waves within this region and note that these waves become active precisely at the time of the current sheet crossing. The coexistence of different types of waves within this region presents a unique opportunity for further investigation and deepening our understanding of the underlying physical mechanisms governing these phenomena.