Time-Distance Analysis of GONG Global Mode Time Series.
|National Solar Observatory/GONG Program|
|Low degree solar and stellar seismology|
|Auteur(s) supplémentaire(s)||Irene Gonzalez Hernandez, Frank Hill, John Leibacher|
|We apply the time-distance technique to the low degree (ell<=200) GONG spherical harmonic time series obtained during the last 14 years. We demonstrate the advantages of low-m filtering in isolating zonal acoustic waves. We analyze temporal variations of mean travel times and meridional travel time differences. Our preliminary results show that mean travel times track solar activity cycle as well as p-mode frequencies. We also present deep meridional travel-time difference maps, and discuss some systematic and technical problems.|