The variation in the strength of low-ℓ solar p-modes: 1981–92

The acoustic eigenmodes of the sun are a well-recognized probe of the structure of the solar interior. We report here on a measurement of the strength of the low-ℓp-mode oscillations throughout a solar cycle. There is an increase of 35 ± 5 percent in the strength of the modes from solar maximum to solar minimum, consistent for all the ℓ-values measured. The observations were made with the Birmingham Solar Oscillations Network (‘BISON’).