Large-scale Control of Kinetic Dissipation in the Solar Wind

In this Letter, we study the connection between the large-scale dynamics of the turbulence cascade and particle heating on kinetic scales. We find that the inertial range turbulence amplitude (δB_i; measured in the range of 0.01-0.1 Hz) is a simple and effective proxy to identify the onset of significant ion heating, and when it is combined with β_{∥ p} , it characterizes the energy partitioning between protons and electrons (T_p/T_e); proton temperature anisotropy (T_⊥T_⊥); and scalar proton temperature (T_p) in a way that is consistent with previous predictions. For a fixed δB_i, the ratio of linear to nonlinear timescales is strongly correlated with the scalar proton temperature in agreement with Matthaeus et al., though for solar wind intervals with β_{⊥ p} > 1 , some discrepancies are found. For a fixed β_{⊥ p}, an increase of the turbulence amplitude leads to higher T_p/T_e ratios, which is consistent with the models of Chandran et al. and Wu et al. We discuss the implications of these findings for our understanding of plasma turbulence.