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Session 9 - SOHO Helioseismology I, Interior.
Oral session, Saturday, June 28
Ballroom A, Chair: Philip Scherrer

[9.01] The Effects of Systematic Errors in the Estimation of p-Mode Frequencies on the Inversion of Solar Internal Structure

E. J. Rhodes Jr. (Univ.Southern Calif. and J.P.L.), T. Appourchaux (ESTEC,E.S.A.), K. Bachmann (Birmingham-Southern Coll.), A. G. Kosovichev, P. H. Scherrer, J. Schou (Stanford Univ.), J. Reiter (Technical Univ.-Meunchen)

The frequencies and associated uncertaianties of the low-, intermdeiate-, and high-degree p-mode oscillations are the input quantities for theinversion programs which infer the thermodynamic structure of the solar interior. In this review we will attempt to demonstrate the different possible systematic errors that are currently present in our estimation of both the modal frequencies and their uncertainties. We will also demonstrate the effects of some of these errors upon the inferred radial profile of the solar internal sound speed. Among the different possible systematic errors which we will discuss are the effects of: 1)the asymmetric shapes of the peaks in obsewrvational power spectra, 2)the realization noise which is present in the case of the low-degree modes, 3)the different frequency estimation methods used on different types of power spectra (i.e., on either tesseral power spoectra or on m-averaged power spectra), 4) the differences in the frequencies which are estimated from velocity- and intensity-based power spectra, 5) the blending of individual p-modes into so-called "ridges" of observed power at both high degrees and high frequencies, and 6) the spatial and temporal aliasing which occurs at both high degrees and at high frequencies. We will demonstrate these different errors using results obtained with the VIRGO and MDI experiments onboard the SOHO spacecraft. We will also compare some of these space-based results with the results of similar estimates obtained from co-temporaneous ground-based observations, such as from the Mt. Wilson 60-Foot Solar Tower. We will include the results from different structural inversions carried out with different sets of input frequencies and uncertainties in order to demonstrate the effects of these different systematic errors upon the inverted internal sound speed profile.

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