Open AccessSolar‐cycle variation of the sound‐speed asphericity from GONG and MDI data 1995–2000
Author(s) -
Antia H.M.,
Basu S.,
Hill F.,
Howe R.,
Komm R.W.,
Schou J.
Publication year - 2001
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.2001.04819.x
Subject(s) - physics , speed of sound , latitude , variation (astronomy) , flux (metallurgy) , magnetic field , sound (geography) , solar cycle , astrophysics , atmospheric sciences , astronomy , acoustics , solar wind , materials science , quantum mechanics , metallurgy
We study the variation of the frequency splitting coefficients describing the solar asphericity in both GONG and MDI data, and use these data to investigate temporal sound‐speed variations as a function of both depth and latitude during the period 1995–2000 and a little beyond. The temporal variations in even splitting coefficients are found to be correlated to the corresponding component of magnetic flux at the solar surface. We confirm that the sound‐speed variations associated with the surface magnetic field are superficial. Temporally averaged results show a significant excess in sound speed around and latitude of 60°.