On the radial evolution of the anisotropy of solar wind fluctuations

The first observations of solar wind parameters, which could also benefit from a radial scanning of the inner heliosphere, revealed that the degree of anisotropy of the IMF fluctuations within Alfvénic time intervals increases with increasing heliocentric distance. Successive analyses, performed within the same intervals, showed that the anisotropy derived from the spectral densities of the Elasässer variable components, at odds with the results from the magnetic field, decreases with increasing heliocentric distance. The present study aims to investigate what causes these contrasting results revisiting, with a different approach, magnetic field fluctuations between 0.3 and 1 AU. Preliminary analyses show that intermittency phenomena play a relevant role.