Imaging the Sun's near-surface flows using mode-coupling analysis

Abstract

The technique of normal-mode coupling is a powerful tool with which to seismically image non-axisymmetric phenomena in the Sun. Here we apply mode coupling in the Cartesian approximation to probe steady, near-surface flows in the Sun. Using Doppler cubes obtained from the Helioseismic and Magnetic Imager onboard the Solar Dynamics Observatory, we perform inversions on mode-coupling measurements to show that the resulting divergence and radial vorticity maps at supergranular length scales ($\sim$30 Mm) near the surface compare extremely well with those obtained using the Local Correlation Tracking method. We find that the Pearson correlation coefficient is $\ge$ 0.9 for divergence flows, while $\ge$ 0.8 is obtained for the radial vorticity.

Accepted for publication in Astrophysical Journal

References in corpus (10)

• Solar inertial modes: Observations, identification, and diagnostic promise
• A low upper limit on the subsurface rise speed of solar active regions
• Supergranulation and multiscale flows in the solar photosphere: Global observations vs. a theory of anisotropic turbulent convection
• Sensitivity of Helioseismic Measurements of Normal-mode Coupling to Flows and Sound-speed Perturbations
• Detection of Rossby modes with even azimuthal orders using helioseismic normal-mode coupling
• Inference of solar rotation from perturbations of acoustic mode eigenfunctions
• Analyzing supergranular power spectra using helioseismic normal-mode coupling
• Inferring solar differential rotation through normal-mode coupling using Bayesian statistics
• Plasma flows and sound-speed perturbations in the average supergranule
• Investigating toroidal flows in the Sun using normal-mode coupling