Investigating Toroidal Flows in the Sun Using Normal-mode Coupling

Helioseismic observations have provided valuable data sets with which to pursue the detailed investigation of solar interior dynamics. Among various methods analyze these data, normal-mode coupling has proven be a powerful tool, used study Rossby waves, differential rotation, meridional circulation, and nonaxisymmetric multiscale subsurface flows. Here, we invert mode-coupling measurements from Magnetic Imager Michelson Doppler obtain mass-conserving toroidal convective flow as function depth, spatial wavenumber, temporal frequency. To ensure that estimates velocity magnitudes are proper, also evaluate correlated realization noise, caused by limited visibility Sun. We benchmark near-surface inversions against results local correlation tracking. The power likely assumes greater latitudinal isotropy decrease in scale flow. note absence peak toroidal-flow at supergranular scales, line show supergranulation is dominantly poloidal nature.