SEARCHING FOR SOLAR CYCLE VARIATIONS OF P-MODE FREQUENCIES GENERATED BY PERTURBATIONS NEAR THE BASE OF THE SOLAR CONVECTION ZONE

摘要

Observations show that the solar p-mode frequencies change with the solar cycle. The horizontal-phase-velocity (ω = ω/ [ι(ι +1)]1/2) dependence of the relative frequency change scaled by mode mass ([δωnl/ωnl]Enl) provides depth information on the perturbation in the solar interior. Our model study suggests that variations of smoothed (δωnl/ωnl)Enl versus w might be able to detect the weak signals generated by the perturbation near the base of the convection zone. We find that the smoothed (δωnl/ωnl)Enl derived from SOHO/MDI data, might show the evidence of solar cycle variations for w higher than a critical value, which corresponds to a depth near the base of the convection zone. The magnitude of temporal variations approximately correlates with solar activity. If these temporal variations are real signals, it suggests that the wave speed in a region near the base of the convection zone change with the solar cycle. It might be related to solar cycle variations of magnetic fields near the base of the convection zone.