Inversions for Average Supergranular Flows Using Finite-frequency Kernels

0388115 - ASÚ 2013 RIV US eng J - Journal Article
Švanda, Michal
Inversions for Average Supergranular Flows Using Finite-frequency Kernels.
Astrophysical Journal Letters. Roč. 759, č. 2 (2012), L29/1-L29/5. ISSN 2041-8205. E-ISSN 2041-8213
R&D Projects: GA ČR GPP209/12/P568; GA AV ČR IAA300030808
Institutional support: RVO:67985815
Keywords : Sun * interior * helioseismology
Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics
Impact factor: 6.345, year: 2012

I analyze the maps recording the travel-time shifts caused by averaged plasma anomalies under an "average supergranule," constructed by means of statistical averaging over 5582 individual supergranules with large divergence signals detected in two months of Helioseismic and Magnetic Imager Dopplergrams. By utilizing a three-dimensional validated time-distance inversion code, I measure a peak vertical velocity of 117 ± 2 m s–1 at depths around 1.2 Mm in the center of the supergranule and a root-mean-square vertical velocity of 21 m s–1 over the area of the supergranule. A discrepancy between this measurement and the measured surface vertical velocity (a few m s–1) can be explained by the existence of the large-amplitude vertical flow under the surface of supergranules with large divergence signals, recently suggested by Duvall & Hanasoge.
Permanent Link: http://hdl.handle.net/11104/0220354