Seismic Constraints on Interior Solar Convection

Abstract

We constrain the velocity spectral distribution of global-scale solar convective cells at depth using techniques of local helioseismology. We calibrate the sensitivity of helioseismic waves to large-scale convective cells in the interior by analyzing simulations of waves propagating through a velocity snapshot of global solar convection via methods of time-distance helioseismology. Applying identical analysis techniques to observations of the Sun, we are able to bound from above the magnitudes of solar convective cells as a function of spatial convective scale. We find that convection at a depth of r/R _sun = 0.95 with spatial extent ell < 20, where ell is the spherical harmonic degree, comprises weak flow systems, on the order of 15 m s^-1 or less. Convective features deeper than r/R _sun = 0.95 are more difficult to image due to the rapidly decreasing sensitivity of helioseismic waves.