Solar Subsurface Flow Inferred Directly from Frequency-Wavenumber Correlations in the Seismic Velocity Field

Abstract

We describe a general strategy for inverting helioseismic data for laterally inhomogeneous (aspherical) structure, in which the physical state of the solar interior is compared directly with inhomogeneity-induced correlations in the observable seismic wave field. The method was used to invert for subsurface supergranular-scale flow using Solar and Heliospheric Observatory Michelson Doppler Imager high spatial resolution Doppler images. Although many approximations were made in carrying out the inversion, general agreement (a correlation coefficient of 0.68) was found between the Doppler component of the seismically inferred flow in the photosphere and the directly observed surface Doppler signal.