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We explore the sensitivity of the frequencies of low-degree solar p-modes tonear-surface magnetic flux on different spatial scales and strengths,specifically to active regions with strong magnetic fields and ephemeralregions with weak magnetic fields. We also use model reconstructions from theliterature to calculate average frequency offsets back to the end of theMaunder minimum. We find that the p-mode frequencies are at least three timesless sensitive (at 95% confidence) to the ephemeral-region field than they areto the active-region field. Frequency shifts between activity cycle minima andmaxima are controlled predominantly by the change of active region flux.Frequency shifts at cycle minima (with respect to a magnetically quiet Sun) aredetermined largely by the ephemeral flux, and are estimated to have been$0.1\,\rm \mu Hz$ or less over the last few minima. We conclude that at epochsof cycle minimum, frequency shifts due to near-surface magnetic activity arenegligible compared to the offsets between observed and model frequencies thatarise from inaccurate modelling of the near-surface layers (the so-calledsurface term). The implication is that this will be the case for other Sun-likestars with similar activity, which has implications for asteroseismic modellingof stars.

Sensitivity of low-degree solar p modes to active and ephemeral regions: frequency shifts back to the Maunder Minimum