Local helioseismology: Three-dimensional imaging of the solar interior

Laurent Gizon, Aaron C. Birch, Henk C. Spruit

Research output: Contribution to journalArticlepeer-review


The Sun supports a rich spectrum of internal waves that are continuously excited by turbulent convection. The Global Oscillation Network Group (GONG) network and the SOHO/MDI (Solar and Heliospheric Observatory/Michelson Doppler Imager) space instrument provide an exceptional database of spatially resolved observations of solar oscillations, covering more than an entire sunspot cycle (11 years). Local helioseismology is a set of tools for probing the solar interior in three dimensions using measurements of wave travel times and local mode frequencies. Local helioseismology has discovered (a) near-surface vector flows associated with convection, (b) 250 m s-1 subsurface horizontal outflows around sunspots, (c) ̃50 m s-1 extended horizontal flows around active regions (converging near the surface and diverging below), (d ) the effect of the Coriolis force on convective flows and active region flows, (e) the subsurface signature of the 15m s-1 poleward meridional flow, ( f ) a ±5 m s-1 time-varying depth-dependent component of the meridional circulation around the mean latitude of activity, and ( g) magnetic activity on the farside of the Sun.

Original languageEnglish (US)
Pages (from-to)289-338
Number of pages50
JournalAnnual Review of Astronomy and Astrophysics
StatePublished - Sep 22 2010


  • Solar convection
  • Solar cycle
  • Solar magnetism
  • Solar oscillations
  • Sunspots

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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