CHANGES TO GLOBAL MODE PARAMETERS OVER A SOLAR CYCLE

摘要

We analyze GONG data for different lengths of observations to study p-mode parameters over a period of ten and a half years of the current activity cycle. We study mode frequencies, amplitudes, and widths derived from time series of length varying from 9 days to 108 days. We find that the frequencies derived from nine days are significantly correlated with the strength of the solar activity and are consistent with long duration measurements from GONG and MDI instruments. We also focus on the solar cycle variation of mode parameters. We find that the mode amplitude and area are anti-correlated while the background amplitude and mode width are uncorrelated with the solar activity. Furthermore, the correlation between the mode parameters and solar activity indices appear to be a function of the length of the time series.