P-MODE FREQUENCY VARIATION IN RELATION TO GLOBAL SOLAR-ACTIVITY

We show that p-mode frequency variations correlate remarkably well wit h the variations of six solar activity indices over a 6 yr period from 1984 October to 1990 November, including both the large variation fro m solar minimum to solar maximum and smaller variations observed over approximately 1 month intervals during solar maximum. The quality of c orrelation as seen visually and as measured by two statistical tests d iffers significantly among the six activity indices, and we briefly sp eculate on possible reasons for this. Observations used in this study come from the HAO/NSO Fourier tachometer (FTACH) and include the spher ical harmonic degree range 20 < l less-than-or-equal-to 60 and frequen cy range 2600 muHz < nu < 3200 muHz (radial orders n between 8 and 15) . The data are divided into 18 separate epochs with time string durati on ranging from a minimum of 18 days to a maximum of 45 days. We have particularly good coverage during the early part of solar maximum of c ycle 22.