The Surface Amplitudes and Frequencies ofp‐Mode Oscillations in Active Regions

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Abstract
It is well established that the surface amplitudes of solar p-mode oscillations are reduced in regions of magnetic activity. In this paper, we examine the conjecture that this reduction is produced by direct modification of the surface values of the p-mode eigenfunctions, rather than changes in the mode energies or alterations in the spectral line formation process. We calculate the oscillation modes of a solar model with a horizontal magnetic field, convection, and radiative diffusion. We find that magnetic fields with strengths characteristic of solar active regions can produce the observed decrease of surface power.