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A.G. Kosovichev (Stanford U.)
The Michelson Doppler Imager (MDI) instrument on SOHO, GONG and other space and ground-based helioseismic experiments provide a unique opportunity for continuous monitoring of the internal structure and dynamics of the Sun. The new data reveal spatial and temporal complexity of internal phenomena such as mixing beneath the base of the convection zone, the subsurface zonal and meridional flows, sound-speed asphericity, polar vortex and others. The exploration of these phenomena by helioseismology is important for understanding the physics of our nearest star.
I discuss progress in the diagnostics of the solar interior, based on 2 years of MDI and 4 years of GONG observations. Accurately measured frequencies of solar oscillation modes have provided detailed information about rotation and structure in the radiative core, the transition region between the convective and radiative zones and the upper convective boundary layer. Substantial progress has been made in achieving better latitudinal and radial resolution in structure and rotation inversions. In addition, new information about the turbulent convection and internal magnetic field is obtained from f-mode data. Further progress in helioseismology crucially depends on understanding the physics of solar oscillations, in particular, the properties of modal lines and ridges in the oscillation power spectra.
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s follows:
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