34th Solar Physics Division Meeting, June 2003
Session 8 Helioseismology
Poster, Monday, June 16, 2003, 3:30-5:00pm, Mezzanine

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[8.04] The LoHCo Project. 1 -- Comparison of Ring-Diagram Local Helioseismology on GONG++, MDI and Mt. Wilson Data Sets

R. S. Bogart, J. Schou (Stanford), S. Basu (Yale), J. Bolding, F. Hill, R. Howe, R. W. Komm, J. W. Leibacher, C. G. Toner (NSO), T. Corbard (Obs. Nice), D. A. Haber, B. W. Hindman, J. Toomre (JILA), E. J. Rhodes, P. J. Rose (USC), LoHCo Project Team

Full deployment of the GONG+ enhanced observing network in October 2001 and implementation of ring-diagram helioseismology in the GONG++ analysis pipeline this year has enabled us to make a detailed intercomparison of results obtained through multiple paths, from observation through each of the analysis steps. Such comparisons can provide a certain degree of validation of the implementations of the analysis procedures, hints of systematic errors, and better characterization of the observations, possibly leading to improved calibrations. The Local Helioseismology Comparison (LoHCo) Project has been established to provide standards for intercomparison of results obtained with different local helioseismic analysis techniques applied to the available observational data sources. We present here a detailed comparison of ring-diagram determinations of localized sub-surface flows and frequency shifts obtained from both MDI and GONG in common observing intervals during Carrington Rotation 1988 (2002/3/30 -- 2002/4/26), using both the MDI and the GONG analysis pipelines. We also present preliminary results of similar analyses of data obtained by the Mt. Wilson MOF during the same times.

This work is partially supported by grants from NASA and NSF.

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Bulletin of the American Astronomical Society, 35 #3
© 2003. The American Astronomical Soceity.