Multiple Scattering of Seismic Waves from Ensembles of Upwardly Lossy Thin Flux Tubes

TL;DR

This study extends previous models of seismic wave scattering by flux tubes to include wave escape at the top, revealing increased absorption and reduced phase shifts, which impacts solar seismic data interpretation.

Contribution

It introduces a radiative boundary condition allowing wave escape at the top of flux tube ensembles, enhancing the realism of seismic scattering models.

Findings

Greater wave absorption due to top escape

Smaller phase shifts observed in emergent waves

Implications for interpreting solar seismic data

Abstract

Our previous semi-analytic treatment of f- and p-mode multiple scattering from ensembles of thin flux tubes (Hanson and Cally, Astrophys. J. 781, 125; 791, 129, 2014) is extended by allowing both sausage and kink waves to freely escape at the top of the model using a radiative boundary condition there. As expected, this additional avenue of escape, supplementing downward loss into the deep solar interior, results in substantially greater absorption of incident f- and p-modes. However, less intuitively, it also yields mildly to substantially smaller phase shifts in waves emerging from the ensemble. This may have implications for the interpretation of seismic data for solar plage regions, and in particular their small measured phase shifts.