Analyzing supergranular power spectra using helioseismic normal-mode coupling

TL;DR

This paper applies mode-coupling helioseismic analysis to study supergranulation power spectra, revealing insights into their dispersion, lifetime, and depth sensitivity, and comparing results with previous studies.

Contribution

It introduces a mode-coupling approach using a Cartesian description to analyze supergranulation, extending the probing depth beyond surface modes.

Findings

Supergranular dispersion relation matches previous results.

Measured supergranulation lifetimes are consistent with literature.

Cross-coupling of higher modes reveals sensitivity to greater depths.

Abstract

Normal-mode coupling is a technique applied to probe the solar interior using surface observations of oscillations. The technique, which is straightforward to implement, makes more use of the seismic information in the wavefield than other comparable local imaging techniques and therefore has the potential to significantly improve current capabilities. Here, we examine supergranulation power spectra using mode-coupling analyses of intermediate-to-high-degree modes by invoking a Cartesian-geometric description of wave propagation under the assumption that the localized patches are much smaller in size than the solar radius. We extract the supergranular power spectrum and compare the results with prior helioseismic studies. Measurements of the dispersion relation and life times of supergranulation, obtained using near surface modes (f and p$_1$), are in accord with the literature. We show that the cross-coupling between the p$_2$ and p$_3$ acoustic modes, which are capable of probing greater depths, are also sensitive to supergranulation.