Emergence of two inertial sub-ranges in solar wind turbulence: dependence on heliospheric distance and solar activity

The solar wind is highly turbulent, and intermittency effects are observed for fluctuations within the inertial range. By analyzing magnetic field spectra and fourth-order moments, we perform a comparative study of intermittency in different types of solar wind measured during periods of solar minima and a maximum. Using eight fast solar wind intervals measured during solar minima between 0.3 au and 3.16 au, we found a clear signature of two inertial sub-ranges with $f^{-3/2}$ and $f^{-5/3}$ power laws in the magnetic power spectra. The intermittency, measured through the scaling law of the kurtosis of magnetic field fluctuations, further confirms the existence of two different power laws separated by a clear break. A systematic study on the evolution of the said sub-ranges as a function of heliospheric distance shows correlation of the break scale with both the turbulence outer scale and the typical ion scales. During solar maximum, we analyzed five intervals for each of Alfv\'enic fast, Alfv\'enic slow and non-Alfv\'enic slow solar wind. Unlike the case during the solar minima, the two sub-ranges are no longer prominent and the Alfv\'enic slow wind is found to be in an intermediate state of turbulence compared to that of the fast wind and the usual non-Alfv\'enic slow wind.