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Imaging of the solar interior: possibilities and limitations

Helioseismic tomography is a promising new method for probing 3-D structures and flows beneath the solar surface. It is based on observation of solar acoustic waves, and provides great possibilities for studying the birth of active regions in the Sun's interior and for understanding the relation between the internal dynamics of active regions and chromospheric and coronal activity. We discuss observational requirements, challenges and limitations of this technique for investigating physical processes in the solar interior on their intrinsic spatial and temporal scales.