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D.A. Haber, B.W. Hindman, J. Toomre (JILA / Univ. of CO, Boulder), R.S. Bogart (Stanford Univ., CSSA-HEPL), F. Hill (NSO-NOAO)
Helioseismic observations taken with SOI-MDI aboard SOHO have led to a new era of discovery about complex and evolving dynamics within the upper solar convection zone. The data now span nearly six years. Using the technique of ring-diagram analysis applied to MDI Dynamics Program Doppler data over a large number of regions on the solar disk, we have generated synoptic maps of horizontal flows at a variety of depths below the photosphere. These maps have been assembled for all of the years for which the SOI-MDI Dynamics Program data are available, with the latest data coming from March 2002. Flows associated with Solar Subsurface Weather (SSW) are observed to vary from month to month and year to year, with the largest flows occurring in and around regions of intense magnetic activity. Longitudinal averages of the flows reveal that the fast banded zonal flows seen in previous years have now merged at the equator while the multiple cell structure found in the meridional circulation within the northern hemisphere over the last four years is still present at a reduced level in 2002. When the average flows are removed, it is possible to see areas of cyclonic flow in regions of quiet sun as well as divergent cells on the order of 30 to 40 degrees in diameter that might be signatures of giant convection cells. This research was supported by NAG5-7996.
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Bulletin of the American Astronomical Society, 34
© 2002. The American Astronomical Soceity.