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  Sensitivity kernels for time-distance helioseismology: Efficient computation for spherically symmetric solar models

Fournier, D., Hanson, C. S., Gizon, L., & Barucq, H. (2018). Sensitivity kernels for time-distance helioseismology: Efficient computation for spherically symmetric solar models. Astronomy and Astrophysics, 616: A 156. doi:10.1051/0004-6361/201833206.

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Genre: Journal Article

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 Creators:
Fournier, Damien1, Author              
Hanson, Chris S.1, Author              
Gizon, Laurent1, Author              
Barucq, Hélène, Author
Affiliations:
1Department Solar and Stellar Interiors, Max Planck Institute for Solar System Research, Max Planck Society, ou_1832287              

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Free keywords: Sun: helioseismology / Sun: oscillations / Sun: interior / methods: numerical
 MPIS_PROJECTS: SDO: German Data Center
 Abstract: Context. The interpretation of helioseismic measurements, such as wave travel-time, is based on the computation of kernels that give the sensitivity of the measurements to localized changes in the solar interior. These kernels are computed using the ray or the Born approximation. The Born approximation is preferable as it takes finite-wavelength effects into account, although it can be computationally expensive. Aims. We propose a fast algorithm to compute travel-time sensitivity kernels under the assumption that the background solar medium is spherically symmetric. Methods. Kernels are typically expressed as products of Green’s functions that depend upon depth, latitude, and longitude. Here, we compute the spherical harmonic decomposition of the kernels and show that the integrals in latitude and longitude can be performed analytically. In particular, the integrals of the product of three associated Legendre polynomials can be computed. Results. The computations are fast and accurate and only require the knowledge of the Green’s function where the source is at the pole. The computation time is reduced by two orders of magnitude compared to other recent computational frameworks. Conclusions. This new method allows flexible and computationally efficient calculations of a large number of kernels, required in addressing key helioseismic problems. For example, the computation of all the kernels required for meridional flow inversion takes less than two hours on 100 cores.

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Language(s): eng - English
 Dates: 2018-09-172018
 Publication Status: Published online
 Pages: -
 Publishing info: -
 Table of Contents: -
 Rev. Type: Peer
 Identifiers: DOI: 10.1051/0004-6361/201833206
 Degree: -

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Title: Astronomy and Astrophysics
  Other : Astron. Astrophys.
Source Genre: Journal
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Publ. Info: Berlin : Springer-Verlag
Pages: - Volume / Issue: 616 Sequence Number: A 156 Start / End Page: - Identifier: ISSN: 0004-6361
CoNE: https://pure.mpg.de/cone/journals/resource/954922828219_1