Seismic Constraints on Interior Solar Convection

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 ☉ = 0.95 with spatial extent ℓ < 20, where ℓ 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 ☉ = 0.95 are more difficult to image due to the rapidly decreasing sensitivity of helioseismic waves.