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M.L. DeRosa, J. Toomre (JILA and Department of Astrophysical and Planetary Sciences, University of Colorado), T.L. Duvall Jr. (NASA / GSFC)
Near-photospheric flow fields deduced using two independent methods applied to the same SOI-MDI time series of images from SOHO are compared. Differences in travel times between incoming and outgoing f modes measured using time-distance helioseismology are used to determine the sites of supergranule outflows. Alternatively, correlation tracking analysis is applied to granular and mesogranular structures seen in time series of Doppler and intensity images. We find that the locations of the supergranular outflows seen in flow fields generated from correlation tracking coincide well with the locations of the outflows determined from the time-distance analysis. The near-surface flow fields provide us with insight in understanding the dyanmics of the turbulent convection occurring below the photosphere. The data consist of four 512-minute time series of high-resolution (0.6'' pixels) Doppler images and continuum intensity images taken by MDI on 17--18 January 1997 at a cadence of one minute.
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