William J. Chaplin (University of Birmingham) Steven J. Hale (University of Birmingham) Rachel Howe (University of Birmingham) Yvonne P. Elsworth (University of Birmingham) Guy R. Davies (University of Birmingham)
We use very high-cadence (sub-minute) observations of the solar mean magnetic field (SMMF), covering a period of more than 20 years, to constrain the lifetimes of active region (AR) flux and ephemeral region (ER) flux on the Sun. The ARs give rise to a rotationally modulated signal in the SMMF observations, which manifest as Lorentzian-like peaks in the frequency domain, whose widths allow us to measure the lifetime of the AR flux. The ERs introduce a stochastic, red-noise-like signal in the SMMF, whose fall off in power with frequency gives an estimation of the lifetime of ER flux. We examine the relative contributions of ARs and ERs to the SMMF and investigate changes in the lifetimes with the changing phase of the solar activity cycle. The data used were collected by the Birmingham Solar-Oscillations Network (BiSON) node in Sutherland, South Africa since 1992.
Mode of presentation: oral (Need to be confirmed by the SOC)