Evidence for Iroshnikov-Kraichnan-Type Turbulence in the Solar Wind Upstream of Interplanetary Traveling Shocks

We analyze suprathermal ions and plasma wave spectra upstream of interplanetary shocks driven by coronal mass ejection events. In particular, we analyze the competition between two processes: (1) the upstream wave generation by suprathermal protons accelerated at the shock, and (2) the cascading of wave energy in the inertial range of solar wind turbulence. We derive the cascading timescale from the comparison of particle and turbulent wave spectra with theory and conclude that amplified solar wind turbulence upstream of interplanetary traveling shocks is better described by Iroshnikov-Kraichnan-type rather than Kolmogorov-type wave diffusion.