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Collisionless magnetohydrodynamic shocks are ubiquitous in solar wind and in other space plasmas. They serve as natural sites where charged particles can be accelerated to supra-thermal energies via various Fermi acceleration mechanisms. Upstream and downstream fluctuations play a key role in these processes because they can act as scatter centers. Furthermore, the downstream turbulent plasma of strong shocks driven by coronal mass ejections can enhance the coupling of this plasma with the Earth’s magnetosphere. Understanding of how the fluctuations are transmitted across the shocks can provide an invaluable insight into many shock related studies.In this paper, we investigate the interaction of fast forward (FF) shocks with magnetic island/flux rope mode fluctuations. We employ a recently developed framework of the Zank et al. (2021) transmission model. We analyze 378 FF shocks observed by the Wind spacecraft with varying upstream conditions and Mach numbers. We estimate upstream and downstream power spectra within one-hour intervals adjacent to the shock front and we calculate theoretically predicted downstream power spectrum. We analyze closely the difference between the observed and theoretically predicted spectra. On average, the model predicts the spectra with very good accuracy. We argue that large statistical spread of this difference is given mainly by the statistical uncertainties in the shock compression ratio, upstream power spectrum and by the turbulent evolution of fluctuations in the downstream region. Finally, our findings also suggest that Zank et al. (2021) model may estimate the downstream levels of fluctuations accurately even for a wider range of shocks than it was originally meant for.

Parker Solar Probe provides a unique opportunity to study anisotropic turbulence in the inner heliosphere. We summarize our recent investigations of solar wind turbulence observed by Parker Solar Probe during its first seven orbits ranging from 0.1 to 0.6 AU. First, we analyzed turbulence anisotropy based on the 2D + slab model and determined the power ratio between the 2D and slab components. We find that the fraction of the 2D component increases with radial distance. Second, we developed a method to identify small-scale magnetic flux ropes and Alfvenic structures based on the reduced magnetic helicity. Alfvenic structures are prevalent in both slow and fast solar wind in PSP's measurements, while the small flux ropes are quasi-2D structures and are relatively abundant near the heliospheric current sheet and slow solar wind. Finally, we analyzed intervals with solar wind velocity strictly parallel to the mean magnetic field. We find a Kolmogorov-like power spectrum with a power-law index of -5/3. Wave activities in both MHD and kinetic scales are also analyzed in these field-aligned intervals. Fast magnetosonic waves and ion-scale waves are identified.