What Deep and Extended Minima Tell us about Magnetism Below the Surface?

Various measures of solar activity show that the minima preceding cycles 24 and 25 were deeper and wider than several earlier minima. These provide a unique opportunity for studying the Sun's properties that are otherwise altered in the presence of strong fields. The solar magnetic field is generated in the interior and the dynamo responsible for 11-year cyclic activity in the Sun is believed to be seated near the base of the convection zone. Here we use oscillation mode frequencies computed from the continuous observations from GONG for the last 25 years to investigate the changes occurring below the surface. Since the oscillation frequencies vary in phase with the solar activity manifested on the surface and exhibit a strong positive correlation, we utilize these frequencies to infer important information on the magnetism of the layers they travel through. We also investigate the similarities and differences between the last two minima.