Comments on the Influence of Solar Activity on P-Mode Oscillation Spectra

Abstract

The systematic p-mode frequency changes which are observed through the solar cycle are believed to be associated with near-surface perturbations confined to the magnetically active latitudes. In this paper, we study the perturbation arising from the presence of a large “active region”, corresponding to a localized structural change in a thin region close to the photosphere. We shall ignore the difficult question of the magnitude of the effect, and simply consider some geometric and observational implications for low-degree modes.