The need for physics-based inversions of sunspot structure and flows

Current controversy exists in the interpretation and modeling of helioseismic signals in and around magnetic regions like sunspots. Unresolved issues include the dependence of the sign of both the inferred flows and wave speed on the type of filtering used, and the discrepancy between the relatively deep two-layer wave-speed models derived from standard time-distance methods and shallow, positive wave-speed models derived using forward models which include effects of mode conversion To make full use of the year-round, almost limb-to-limb, coverage provided by the Solar Dynamics Observatory, an efficient and reliable inversion method incorporating possible magnetic effects and the currently unexplained sensitivity to methodology is critical.