34th Solar Physics Division Meeting, June 2003
Session 26 The Changing Solar interior II
Oral, Friday, June 20, 2003, 9:00am-12:00noon, Auditorium

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[26.09] Synoptic Maps of Mass Flows Beneath the Solar Surface by Time-Distance Helioseismology

J. Zhao, A. G. Kosovichev (W.W. Hansen Experimental Phyiscs Laboratory, Stanford University)

We have derived the subsurface horizontal flow velocity fields for several solar Carrington rotations from 1996 to 2001, covering the period from the activity minimum to maximum of solar cycle 23, by analyzing SOHO/MDI Dynamics data. The synoptic flow maps have been made from the near-surface down to 12 megameters below the photosphere. The torsional oscillation and meridional flows, as well as the flow vorticity have been calculated from the flow maps as a function of latitude. It is found that after the subtraction of the solar minimum data, the residual meridional flows converge toward the activity belts, and migrate toward the equator together with the sunspot zones. In addition, the corresponding residual vorticity peaks in the activity belts, having the opposite signs in Northern and Southern hemispheres. Comparing the synoptic flow maps with the synoptic magnetic field maps, it is found that the solar plasma rotates faster where the photospheric magnetic field is stronger. An approximate linear relation between the magnetic strength and the rotational speed has been obtained from these data.

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