Acoustic power absorption and enhancement generated by slow and fast MHD waves Evidence of solar cycle velocity/intensity amplitude changes consistent with the mode conversion theory

We used long duration, high quality, unresolved (Sun-as-a star) observations collected by the ground based network BiSON and by the instruments GOLF and VIRGO on board the ESA/NASA SOHO satellite to search for solar-cycle-related changes in mode characteristics in velocity and continuum intensity for the frequency range between 2.5 mHz <v <6.8 mHz. Over the ascending phase of solar cycle 23 we found a suppression in the p-mode amplitudes both in the velocity and intensity data between 2.5 mHz <v <4.5 mHz with a maximum suppression for frequencies in the range between 2.5 mHz <v <3.5 mHz. The size of the amplitude suppression is 13 +/- 2 per cent for the velocity and 9 +/- 2 per cent for the intensity observations. Over the range of 4.5 mHz <v <5.5 mHz the findings hint within the errors to a null change both in the velocity and intensity amplitudes. At still higher frequencies, in the so called High-frequency Interference Peaks (HIPs) between 5.8 mHz