Non-self-similar scaling of plasma sheet and solar wind probability distribution functions of magnetic field fluctuations

Abstract

Solar wind magnetometer and plasma data and magnetometer data acquired by Cluster in the magnetospheric plasma sheet are employed to construct probability distribution functions (PDFs) of magnetic field fluctuations over various temporal and spatial scales. This technique, often used in analysis of laboratory plasmas, is used to look for intermittent plasma turbulence and non-self-similar properties in the fluctuations. We examine the distribution of the magnetic field fluctuations for a single spacecraft and between pairs of correlated spacecraft time series data in both the plasma sheet and the solar wind (fast and slow speed streams). We demonstrate that the plasma sheet fluctuations have a distribution consistent with intermittent turbulence and that they scale non-self-similarly using two different methods (Sorriso-Valvo et al., 1999; Hnat et al., 2002). In the solar wind both methods show that the fast solar wind magnetic field fluctuations have a PDF consistent with intermittent turbulence and scale non-self-similarly, but the two methods give conflicting results for the slow solar wind scaling properties. Finally, we use the results of the two methods as well as kurtosis versus scale size to roughly determine the turbulent eddy scale size in both types of solar wind (about 500 RE) and the magnetospheric plasma sheet (between 0.9 and 1.5 RE).