Identification of inertial modes in the solar convection zone

Abstract

The observation of global acoustic waves (p modes) in the Sun has been key to unveiling its internal structure and dynamics. A different kind of wave, known as sectoral Rossby modes, have been observed and identified, which potentially opens the door to probing internal processes that are inaccessible through p mode helioseismology. Yet another set of waves, appearing as retrograde-propagating, equatorially antisymmetric vorticity waves, have also been observed but their identification remained elusive. Here, through a numerical model implemented as an eigenvalue problem, we provide evidence supporting the identification of those waves as a class of inertial eigenmodes, distinct from the Rossby mode class, with radial velocities comparable to the horizontal ones deep in the convective zone, but still small compared to the horizontal velocities towards the surface. We also suggest that the signature of tesseral-like Rossby modes might be present in the recent observational data.