Identifying Acoustic Wave Sources on the Sun. II. Improved Filter Techniques for Source Wavefield Seismology

Abstract

Abstract In this paper, we refine a previously developed acoustic source filter, improving its reliability and extending its capabilities. We demonstrate how to fine-tune the filter to meet observational constraints and focus on specific wave-front speeds. This refinement enables discrimination of acoustic source depths and tracking of local source wave fronts, thereby facilitating ultralocal helioseismology. By utilizing the photospheric Doppler signal from a subsurface source in a MURaM simulation, we demonstrate that robust ultralocal three-dimensional helioseismic inversions for the granular flows and the local sound speed to depths of at least 80 km below the photosphere are possible. The capabilities of the National Science Foundation’s new Daniel K. Inouye Solar Telescope will enable such measurements of the real Sun.