Evolution of Turbulent Fluctuations across Terrestrial Bow Shock

Magnetohydrodynamic (MHD) shocks are one of the key nonlinear phenomena which occur in plasmas and can influence a dynamical evolution of a system at wide range of spatial scales. In the vicinity of the shock fronts, a majority of the dissipation of the incident bulk energy takes place. Furthermore, the incident fluctuations have profound effect on the shock front itself and also on the respective evolution of the transmitted/generated modes. Recently, several approaches have been developed focusing on the evolution of various plasma wave modes across MHD shocks. In this work, we investigate the transmission of quasi-2D turbulent fluctuations across fast forward shocks in the framework of the Zank et al. (2021) model. We take advantage of concurrent measurements of upstream and downstream plasma of a terrestrial bow shock, employing observations of the Wind spacecraft and Magnetophere Multiscale Mission (MMS). This partially mitigates two main limitations of single spacecraft studies, (a) the variability of incident plasma and magnetic field fluctuations and (b) the effects that stem from the evolution of fluctuations as they propagate away from the shock front. Our results suggest that the Zank et al. (2021) model predicts the downstream levels of fluctuations excellently for the quasi-perpendicular regime of the bow shock. We discuss the deviations between the predicted and observed levels of downstream fluctuations, highlighting the influence of bow shock nonplanarity and variable obliquity.