Radial increase of the compensated interplanetary magnetic field magnitude as a result of the growth of spherically polarized Alfvén waves

Measurements from the NASA Parker Solar Probe (PSP) mission demonstrate that inside $\sim20$ solar radii ($\Rs$) the magnitude of the interplanetary magnetic field does not fall off simply as $1/R^2$, with $\avg{|B|}\,R^2$ 15--20\% below its value at $\sim60\,\Rs$. Here we use PSP magnetic field mea