Evidence for radial variations in the equatorial profile of the solar internal angular velocity

Abstract

We present evidence that the solar internal angular velocity, at least as measured in the equatorial plane, shows systematic radial variations in the outer half (by radius of the solar interior. Specifically, we employ the rotationally-induced frequency splittings of both high- and intermediate-degree sectoral p-mode oscillations to demonstrate that the internal angular velocity rises inwardly from the observed spectroscopic rotation rate of the photospheric gas to a higher value that is at least equal to the observed rotation rate of sunspots, if not higher, in the outer third of the convection zone before decreasing inward of the convection zone to a value which is at least two percent below the photospheric gas rotation rate. By making the assumption that the observed splittings are sensitive to solar rotation at the midpoints of the p-mode eigenfunctions we obtain an angular velocity profile which rises from 452 nHz at the photosphere to 462 nHz at a depth of about five percent of the solar radius below the photosphere. A comparison of this inferred angular velocity profile with that obtained from a formal inversion of these splittings (which is reported elsewhere in these proceedings by Korzennik et al.) suggests that the angular velocity might actually exceed the magnetic rotation rate over much of the convection zone before decreasing inwardly toward the center of the sun.