Center-to-limb variation of the solar oscillation - New results from MDI data

Using 17 hours of full-disk MDI Doppler data we have investigated the cente r-to-limb variation of the oscillatory wave spectrum of the solar photosphe re. Power distributions in the k(h)v-plane are calculated for fields of 20 degrees x 20 degrees on the Sun, centered at every 10 degrees heliographic latitude. From the center-to-limb variation of the power in the f mode and the lowest 7 p modes we obtain information about the mean inclination of th e oscillatory velocity vector with respect to the vertical direction. We fi nd qualitative agreement with a model of adiabatic waves in an isothermal a tmosphere, but generally the solar oscillations appear to be less inclined than the model oscillations. We find no indication for the existence of hor izontal sound waves on the Sun.