Time decorrelation in isotropic magnetohydrodynamic turbulence

Time decorrelation in isotropic incompressible magnetohydrodynamic (MHD) turbulence is studied using three-dimensional numerical simulation. Eulerian and wavenumber-dependent correlation functions are obtained. Scaling with wavenumber separates effects of nonlinear distortion and effects of random sweeping and Alfvenic wave propagation. Results show that the dominant effect is the combined influence of convective sweeping and Alfvenic propagation, both being nonlocal effects on small-scale fluctuations by large-scale fluctuations. This conclusion finds applications in space plasma observation, particle scattering, predictability, and turbulence theory.