Magnetic Field Strength Distribution in Interplanetary Turbulence

T. Hartlep, W. H. Matthaeus, N. S. Padhye and C. W. Smith

Journal of Geophysical Research, in press, 1999.


The distribution of magnetic field magnitudes is derived for the special case of a constant mean field and uncorrelated components having Gaussian distributions. Of the three cases considered -- isotropic, transverse, and axisymmetric, the latter most closely resembles a lognormal distribution, when the parallel variance is less than the perpendicular variance. Thus, a normally distributed, non-intermittent vector field can produce a magnitude distribution that closely resembles a functional form often associated with models of intermittency. This result is illustrated by comparison with a magnetic field magnitude distribution computed from the 1 AU Omni dataset. The parameters of the Gaussian component magnitude distribution can be chosen to compare with the data which is also well fit as a lognormal type. We conclude that the magnitude distribution may not be a sensitive indicator of intermittency, and that further examination of the sensitivity of such indicators is warranted.

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