Wave‐driven Turbulent Coronal Heating in Open Field Line Regions: Nonlinear Phenomenological Model

Abstract

A model is presented to investigate the driving of coronal turbulence in open field line regions, powered by low-frequency oscillatory field line motions at the coronal base. The model incorporates the combined effects of wave propagation, reflection associated with gradients of Alfven speed, and low-frequency quasi-two-dimensional turbulence, which is treated using a one-point closure phenomenology appropriate to a transverse cascade in the reduced magnetohydrodynamic regime. Considering a sample of the corona and employing open boundary conditions, we use the model to investigate the dynamical efficiency of turbulent dissipation, which competes with propagation of fluctuations away from the coronal base. We examine the dependence of the heating efficiency on wave-forcing frequency, the sensitivity to parameters controlling the Alfven speed profile, the behavior of the model for varying the phenomenological correlation length of turbulence, including asymptotic limits of negligible or very intense nonlinearities, and the confinement of turbulent dissipation to the region near the coronal base. Each of these issues may be of importance in understanding the heating of the corona and the origin of the solar wind.