Authors: Nooshin Mashayekhizadeh ( University of New Hampshire), Benjamin Chandran ( University of New Hampshire)
Near Earth, the power spectrum of magnetic field fluctuations in the fast solar wind (VSW > 500 km s-1 ) at magnetohydrodynamic (MHD) scales is characterized by a double power law, with power-law indices -1 and −5/3. The latter corresponds to the MHD turbulence inertial range, while the former, so-called 1/f range, is considered the energy reservoir feeding the turbulent cascade.
We present measurements of the fast solar wind from Parker Solar Probe’s encounter 10 with the Sun, which we use to investigate the evolution of solar wind turbulence and signatures of the development of a 1/f spectrum in the inner heliosphere. Our results suggest that the 1/f spectrum that is often seen at large heliocentric distance in the fast solar wind is not produced at the Sun, but instead develops dynamically as the wind expands outward from the corona into the interplanetary medium.