Poster abstract details

Doppler velocity or intensity observations of the unresolved Sun allow the investigation of the global properties of the low angular degree p-modes. Long high-quality helioseismic data covering the complete full solar cycle 23 are provided by the ground-based network such as BiSON and by the space-based experiments such as GOLF and VIRGO/SPM on board the ESA/SOHO spacecraft. Therefore, it has been possible to investigate the changes induced by the solar cycle on the p-mode frequencies, amplitudes and linewidths. Although the dependence of the variations in the p-mode parameters with solar magnetic activity is very well known in literature, it is still an open debate over what the mechanism behind it is. Recently, mode conversion has become the preferred mechanism to explain acoustic-power absorption in and/or around sunspots. We explore the possibility, that the solar cycle changes in p-mode parameters between 2.5$<\nu<$5.2 mHz, observed in integrated sunlight observations, can also be explained in terms of mode conversion. Towards this aim, we compare the frequency dependence of the variations in p-mode velocity amplitude and frequency over the solar cycle with theoretical predictions of mode conversion. The results of this investigation may confirm the suggestion that the near surface magnetic field is interacting with the solar oscillations, as suggested by mode conversion theory, which is important to consider when using helioseismology to infer the interior structure of the Sun.