SPECTRAL SCALING LAWS IN MAGNETOHYDRODYNAMIC TURBULENCE SIMULATIONS AND IN THE SOLAR WIND

The question is addressed as to what extent incompressible magnetohydrodynamics can describe random magnetic and velocity fluctuations measured in the solar wind. It is demonstrated that distributions of spectral indices for the velocity, magnetic field, and total energy obtained from high-resolution numerical simulations of magnetohydrodynamic turbulence are qualitatively and quantitatively similar to solar wind observations at 1 AU. Both simulations and observations show that in the inertial range the magnetic field spectrum E-b is steeper than the velocity spectrum E-v with E-b greater than or similar to E-v and that the magnitude of the residual energy E-R = E-v - E-b decreases nearly following a k(perpendicular to)(-2) scaling.