Born Kernels for the Helioseismic Fourier-Legendre Analysis Method
Abstract
Measuring large-scale flows like the meridional flow with helioseismic methods plays a crucial role for understanding solar dynamics. In this work, we develop a detailed forward model for the Fourier-Legendre analysis method. This method has initially been applied for measuring the meridional flow by Braun & Fan, who observed frequency shifts between poleward and equatorward traveling p-modes. However, a detailed theoretical model based on a description of the solar internal wavefield is lacking. We therefore describe the effect of advection on the acoustic wavefronts in the first Born approximation following the framework of Gizon & Birch. We derive 2D sensitivity kernels for a suitable and unified definition of the frequency shift, and validate them on the example of a meridional flow. Finally, an inversion technique to estimate the meridional flow is developed on the basis of synthetic data from a simulation of linear wave propagation.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- August 2018
- DOI:
- 10.3847/1538-4357/aacd4a
- Bibcode:
- 2018ApJ...862..145H
- Keywords:
-
- methods: data analysis;
- methods: numerical;
- Sun: helioseismology;
- Sun: interior;
- Sun: oscillations;
- waves